Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a pipelaying barge, and
more particularly to a twin hull column stabilized semisub-
mersible pipe laying barge carrying a pipe assemhly line and
means for laying pipeline onto the sea bottom and to methods
of operating such barge.
Increased offshore activities, such as attempts to
drill and exploit gas and oil wells at sea, have created a
demand for underwater pipelines for transporting gas and oil
from offshore wells or production sites to near-shore or
on-shore terminals for storage and/or ultimate delivery of
- 2 -
:`~.. ' . .: ' . ' : : '
`'' " '. "'" ' ' ' ' :~"' ' ' ' ': '
~ , I .
: ' -
"`' . , ~ :' ' '',`" : , ~
.,, ~ . , , ,, , . , , , ,~ .. .
103~6~
the gas and/or oil to refineries and to the consumer. To
date t large numbers of pipelines have been laid offshore along
the sea bottom by conventional pipelaying barges to connect
the production sites with the near-shore or on-shore facili-
ties, Such conventional barges are usually characterized by ~-
a single standard barge hull which is generally rectangular
in shape (with a bow at the front) and operates in surface
floating condition (not semi-submerged~ with a pipe section
assembly line normally disposed along the hulls topside and
along which pipe sections are welded one to the other; the
pipeline is payed out from the stern of the barge which is
not much above the water line and generally over a stinger
which extends from the barge stern and supports the portion
of the pipeline which initially enters the water, Pipelaying ~;
operations have heretofore generally been conducted in rela-
tively calm or sheltered waters; where conducted in regions
having medium to h~gh seas (waves in excess of 4 to 5 feet) ;,
such operations are usually suspended until such sea3 subside
and calm conditions arise. That is, conventional pipelaying
operations are highly restricted by sea state condition sinc~
excessive motion in pitch~ heave and roll~ especially pitch,
can excessively stress the pipe to cause rupture of the pipe
and/or its concrete coating, Also, on-deck equipment of~en
is damaged or lost due to wave action,
Conventional pipelaying barges which are single hull
surface floating vessels have stability characteristics which
provide excessive motion in even moderate sea conditions
- 3 -
:-.; . ., : .
0~
whe~eby pipelaying operations are highly restricted by sea
state conditions since excessive vessel motîon in heave, pitch
and roll even in relatively moderate sea conditions can alter
the curvature of the pipeline being laid to the extent of
exceeding allowable stresses with resultant rupture of pipe
or coating For example, surface floating pipelaying barges
of this type can operate only in sea states having wave
heights up to about 4 or 5 feet or in special cases six
feet Wave aetion against such barges, when in sea states
having wave heights in excess of these limits, normally causes
excessive vessel motion which precludes pipelaying operations.
Such conventional single hull vessels have inherently low
natural periods in roll, pitch and heave and inherently high
GM. The low natural periods are apt to be close to the ~
period of the waves, thus causing motion amplification while a
high GM results in high stability and consequent abrupt and
large correcting motions when the barge is subjected to roll
and pitch excitations. The above-discussed stability and
motion characteristics of the described conventional pipelay-
ing barges do not permit pipelaying operations to proceed in
medium and high sea states.
Due particularly to the discovery and exploitation
of oil and gas in the North Sea and other offshore areas
which are consistently and continuously subject to relatively
high wind and sea states, there has been and is a need for a
vessel which can operate to continuously lay pipe in such
waters notwithstanding such high sea states Pipelines have
4 _
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: . , . - . .
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1039Q68
been and are continuing to be success~ully laid in one such ~-
region, i.e, the North Sea, by two semisubm4rsible twin hull
column stabilized derrick barges o~ the type disclosed in U.S.
Patents No, 3,835,800 and No. 3,685,305 and No. 3,704,596
(owned by the assignee of this application) such derrick
barges having been modifiPd to carry pipe assembly lines and
ancillary equipment for pipelaying operations and including
deck-to-water pipe section transition stingers such as dis-
closed in said U.S. Patents Nos. 3,685,305 and 3,704,596.
The present invention provides a novel improved
semi-submersi~le twin hulled column stabilized pipelaying
barge construction and system which not only provides advan-
~ages over above-discussed conventional pipelaying barges
(which are fundamentally different from the pipelaying vessel
o this application), but also provides novel features and
advantages for pipelaying which are not incorporated as such
in the vessels disclosed in the three pat0nts identified in
the immediately preceding paragraph.
Accordingly, it is a primary object of the present
invention to provide novel and improved apparatus and methods
of operation relating to a semisubmersible column stabilized
pipelaying barge which would generally preclude pipelaying
operations by conventional single hull barges and which also
provides new advantageous features as compared to the afore-
mentioned semisubmersible derrick barges of assignee's afore-
mentioned patents when used as pipe layers.
- 5 -
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. . . .
~39~6~3
It is another object of the present invention to
provide a novel and improved column stabilîzed semisubmersible
twin hull pipelaying barge having one or more cranes movable
longitudinally along the barge platform for general lifting
purposes including resupply of pipe sections to the barge and
to the pipe assembly line from supply boats; and novel and
improved methods for operating such barge in semi-submerged
high draft condition.
It is still another object of the present invention
to provide a novel and improved twin hull semisubmersible
column stabilized pipelaying barge and method of operating
such barge wherein the barge in high draft condition is bal- :
lasted in correlation to the location and/or movemen~ of the
crane or cranes along the platform to maintain the attitude of
the barge in trim within a predetermined angle of change from
the operational trim angle set prior to change in location
.~ . .
and/or movement of the crane or cranes along the barge and to
maintain such angle within narrow limits to prevent ~xcess
resultant stresses on the pipeline exceeding allowable
stresses which would damage the pipeline and/or any coating
applied to the pipeline,
:~ It is a further object of the present invention to
...~
provide a novel and improved twin hull semisubmersible column
stabilized pipelaying barge and method of operating such barge
wherein the barge in high draft condition is ballasted in
conjunction with and correlation to the location and/or
.
:` - 6 --
.,
103906~
movement of the crane or cranes along the plat~orm to maintain
the attitude of the barge in trim within plus or miDus one-half :
degree of a preset operational trim angle.
It is a still further object of the present invention ~ ~
to provide a novel and improved twin hull semisubmersible
column stabilized pipelayer barge with means for establishing
proper distance between the top of the hulls and the mean
waterline at "load line draft" in the high draft condition
of the barge for such pipelaying barges having a particular
column height between the hulls and platform.
It i~ an even further object of the present invention
to provide a novel and improved pipelaying combination including
a twin hull semisubmersible column stabilized pipelayer barge
and a pipeline transition segment wherein the pipeline
transition segment is adjustable about a transversely
extending axis in relation to the attitude of the barge about
its trim axis and to the horizontal to control the curvature
of the pipeline extending from the barge and over the pipeline
traDsition segment so as not to exceed allowable stresses on
the pipeline and its coating and also with such adjustment
being made in conjunction with and correlation to operation
of the ballast means for maintaining the draft of the barge
in the desired high draft condition and also maintaining the
barg~ trim angle less than plus or minus one-half degree
variation from the preset angle of trim whereby the relative
angular relation between the barge and pipeline transition
- . . . . . . .
:. , , , . . ~- .: .
~039~$~
segment is substantially maintained throughout pipelaying
operations so as not to exceed allowable stresses on the
pipeline and/or its coating.
In accordance with one broad aspect, the invention .
relates ~o a column stabilized semisubmersible pipelaying
barge and pipeline transition combination comprising: a pair
of elongated hulls disposed in spaced side-by-side relation; :
a working platform spaced above said hulls a predetermined .
height; means for supporting said platform in spaced relation ~:
above said hulls including columns connected to said hulls and
said platform; the distance between the extremities of said :
barge along the longitudinal centerline of said barge being :
substantially greater than the distance between the extremities
of said barge along the transverse centerline thereof; said
hulls having ballast compartments for ballasting said barge ~to alter its draft between a low draft hull supported :
floating condition and a high draft semisubmerged column
stabilized and pipelaying operating condition; said columns
having predetermined cross-sectional areas and being located ~
on the hulls to provide righting moments about the pitch and :
roll axes of said barge when in said high draft semisubmerged :
condition; the area of said columns, the number thereof, and
the distance of the columns from the longitudinal and transverse
centerlines of the barge being such as to provide a greater
righting moment about the transverse pitch axis than the
righting moment about the longitudinal roll axis when the
barge is in high draft semisubmerged pipelaying operating
condition; means for supporting and paying out pipeline from
one end of said barge including pipeline transition means for !~
supporting the pipeline extending from said barge end into the
water; means including said pipeline transition means for
. . ~
controlling the curvature of a segment of the pipeline extendinq
--8
.... , , ~ , .
9~
from said barge end and over said pipeline transition means;
crane means carried by said barge with means mounting said
crane means for movement substantially longitudinally of the
barge along said platform; said crane means including means .
for lifting, transferring and setting loads and being of a size,
weight and capacity such that longitudinal movement of said
crane means along the barge platform a predetermined distance . ~.
when said barge is in said high draft semisubmerged pipelaying
condition will cause change in the angle of trim of the barge
exceeding about plus or ~inus one-half degree as compared to the
barge angle of trim prior to such longitudinal movement of the
crane means absent sufficient connter-correction of such
change in barge trim angle caused by such movement of said
crane means; ballast means for counteracting the change in
angle of trim of the barge caused by movement of said crane -
means longitudinally along said platform to maintain the
angle of trim of said barge within an angle of change about the
trim axis so that the curvature of the pipeline extending from
said barge end and over said pipeline transition section does
not exceed allowable stress for the pipeline and any coating
on the pipeline.
In accordance with another aspect, the invention
relates to a column-stabilized semi-submersible barge
comprising: a pair of elongated hulls disposed in spaced
side-by-side relation; a working platform spaced above said
hulls a predetermined height; means for supporting said
platform in spaced relation above said hulls including columns
connected to said hulls and said platform; the distance between
the extremities of said barge along the longitudinal ~enterline
of said barge being at least 2.5 times greater than the
distance between the extremities of said barge along the
trans~erse centerline thereof; said hulls having ballast
~ -8A-
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~03~ 8
compartments for ballasting said barge to alter its draft
between a low-draft hull supported floating condition and a :~
high-draft semi~submerged column-stabilized operating
condition; said columns having predetermined cross-sectional
areas and being locatea on the hulls to provide righting :~
moments about the pitch and roll axes of said barge when in
said high-draft semi-submerged condition; the area of said
columns, the number thereof, and the distance of the columns
from the longitudinal and transverse centerlines of the barge
being such as to provide a greater righting moment about the :~
transverse pitch axis than the righting moment about the
longitudinal roll axis when the barge is in high-draft semi-
submerged operating condition; crane means carried by said :
barge with means mounting said crane means for movement
substantially longitudinally of the barge along said platform;
said crane means including means for lifting, transferring
and setting loads and being of a size, weight and capacity
such that longitudinal movement of said crane means along the
barge platform a predetermined distance when said barge is in
said high~draft semi-submerged operating condition will cause
change in the angle of trim of the barge exceeding about plus
or minus one-half degree as compared to the barge angie of
trim prior to such longitudinal movement of the crane means
absent sufficient counter-correction of such change in barge
trim angle caused by such movement of said crane means; ballast
means for counteracting the change in angle of trim of the
barge caused by movement of said crane means longitudinally
along said platform to maintain the angle of trim of said barge
within an angle of change about the trLm axis of plus o, minus
oné-half degree from such angle of trim existing prior to
longitudinal movement of said crane means.
These and other related objects and advantages of the
~ -8B-
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1(~3~;8
present invention will become more ~pparent upon reference to
the following specification, appended claims and drawings
wherein:
FIGURE 1 is a side elevational view of a pipelaying
barge constr~cted in accordance with the present invention
with a transition segment illustrated i~ semi-submerged
floating condition for pipelaying operations;
FIGURE 2 is a plan view of the pipelaying barge and
transition segment shown in FIGURE l;
FIGURE 3 is an enlarged horizontal cross-sectional view
of the barge taken generally about on line 3-3 in FIGURE l;
FIGURES 4 and 5 are enlarged sross-sectional views
taken generally about on lines 4~4 and 5-5 respectively in
FIGURE 3;
FIGURE 6 is a schematic view of one of the hulls of
the vessel illustrating the ballast system therefor;
FIGURE 7 is a side elevational view of a pipelaying
barge constructed in accordance with another embodiment of the
present invention and illustrated in high draft pipelaying
condition;
FIGURE 8 is a plan view of the pipelaying barge
illustrated in FIGURE 7;
i r~.~ ,- ~8C-
~V3 ~ 8
FIGURE 9 is an enlarged cross-sectional view o~ -
the barge of FIGURE 7 taken generally about on line 9-9
in FIGURE 7;
FIGURE 1~ is a fragmentary horizontal cross-
sectional view of the aft end of the barge and plan view of
the forward end of the transi~ion segment;
FIGURES llA, llB, 11~ and llD are schematic
illustrations of the pipelaying barge illustrating the change
in the trim attitude of the vessel in response to longitudinal
movement of the crane between stern and pitch axis and the
ballast correc~ion to counteract the change in the angle of
trim induced by crane movement;
FIGURES 12A, 12B, aT~d 12C are similar schematlc
illustrations of the barge illustrating changes in the atti-
tude of the barge in response to longitudinal movement of the
crane between locations aft and forward of the pitch axis and
ballast correction to maintain the attitude of ~he barge
within the preset operational trim attitude;
FIGURE 13 is a graph which plots along the ordinate
the distance from the hull top to load line draft called "LLD"
versus various barge column height "BCH" along the absicca;
and
FIGURES 14A-14D are schematic illustrations of the
pipelaying barge and transition segment (similar to
FIGURES llA-llD and 12A-12C) and FICURE 14E is a schematic
illustration in horizontal cross section through the columns;
i~39(~f~8
the loads, loci, distances, moments, axes, etc. designated
in drawing FIGURES 14A-E, for example "CL","BMC", '~TA", etc
are defined later in the specification for use in the
appended claims with reference to drawing FIGURES 14A-E
(and other drawing Figures such as FIGURES 13 and 1 as
discussed below).
Referring to the drawings, particularly to
FIGURES 1 and 2~ there is illustrated a column stabilized,
semi-submersible pipe laying barge or vessel constructed in
accordance with one embodiment of the present invention and
generally indicated 10. Barge 10 includes a pair of
transversely spaced, elongated hulls 12 extending in spaced ~;
parallel relation and providing sufficient displacement to
support barge 10 in a low-dr$ft floating condition with the
hulls 12 having freeboard indicated '~" in FIGURE 1. Each
hull has a bow suitably shaped to reduce resistance to movement
of barge 10 through the water when it is moved in the low-draft
floating condition. Each hull 12 is also substantially rectan-
gular in cross section with parallel planar top and bottom
surfaces extending substantially the entire length of the
hull for reasons discussed hereinafter; it will be appreciated,
however, that each hull cross section may have rounded corner
edges and that the sides of the hulls may be arcuate, i.e.
laterally outwardly conve~ in shape between the top and
bottom hull surfaces.
--10-
.
1039~8
A platform generally designated P and comprising
a main deck 16 and a lower deck 18, is supported a predeter-
mined height above the hulls 12 by support structure including
a plurality of longitudinally spaced transversely extending
truss formations generally indicated 20 and 30 and a plurality
of longi~udinally spaced pairs of transversely spaced
stabilizing columns 22. As illustrated in FIGURE 1, a
plurality of the truss formations 20 are longitudinally .
spaced between each longitudinally spaced pair of columns 22
and each such truss formation includes as illustrated in
FIGURE 5, two outermost support members 24 upstanding from
the outer side of each hull 12 to the outer edges oflower
deck 18; a plurality of diagonal or inclined beams 26
secured between each hull 12 and lower deck 18 providing
support for platform P; and a transversely ex~ending
horizontal cross beam 28 joining the upper inner sides of
hulls 12 one to the other. A truss formation 30 connects
between hulls 12 in the area between each pair of transversely .
adjacent columns 22 with two such truss formations 30 being ; ;
located between the fore and aft pairs of columns 22, As
illustrated in FIGURE 4, each truss formation 30 includes
beams 32 inclined from the interior edges of the hulls toward
one another for connection to the lower deck 18 of platform P
and a transverse horizontal cross beam 34 joining the upper
inner sides of hulls 12 one to the other. Additional vertic- -
ally extending support members 35 also structurally inter-
connect hulls 12 and platform P. ~:
, , ~ ........ . .
~ a~390~
The truss formations 20 and 30 rein~orce the structural
relationship of the hulls, platform and columns and restrain,
particularly by means of the cross beams 28 and 32, the hulls
12 against lateral displacement re~ative to one anotherO ~ -
As discussed more fully herelnafter, the support
structure also includes stabilizing columns 22 which extend
upwardly from the upper surfaces of hulls 12 to platform P ~
a predetermined height, preferably greater than the maximum - `
anticipated wave height (i.e. the vertical distance between
wave crest and trough). In the preferred embodiment, four
pairs of columns 22 are equally longitudinally spaced one
from the other along hulls 12 with the column arrangement on
each hull being symmetrical with respect to the column
arrangement on the other hull, As shown in FIGURE 3, each
column 22 is generally oblong in shape and is arranged such
that the long axis of its cross section lies parallel to the
longitudinal centerline of the barge. Each column 22, as
illustrated in FIGURE 3, has longitudinally transver~ely
spaced inner and outer vertical sides and semi-cylindrical
ore and aft vertical end sections 36, The columns, however,
may have circular, square, octagonal, elliptical or other
horizontal cross-sectional configurations and need not have
e~ual cross-sectional areas as illustrated herein, Symmetry
of the cross-sectional areas of the columns about the pitch
and roll axis of the barge is preferred.
-12-
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:
1(13~68
However, it is important that each column 22 have a
constant cross-sectional area at least for the intermediate
portion of the column which extends vertically from a point
located 0 25 of the total column height above the hulls 12 to
a point located 0 75 of the total column height above the
hulls (the latter point being 0 25 of the total column height
below the platform P) That is, the middle half of each
column 22 is constant in cross-sectional area; preferably,
the columns 22 are constant in cross-sectional area throughout
their entire length, but either or both the upper and lower
ends of the columns may have different cross sections, for
example, to facilitate structural connection between the
columns 22 and the hulls 12 ~nd platform P providing such
different cross sections are of a configuration which do not
adversely affect the operating characteristics of the barge
when in high draft semi-submerged condition for pipelaying
as amplified hereinafter. Preferably~ the columns are
located along the outboard sides of hulls 12 such that the
outboard vertical sides of the columns 22 form vertical
extensions of the outboard sides of the hulls, as illustrated
in FIGURES 3 and 4. The centroids of the cross section of
the columns are also preferably located outboard of the center-
line of each hull 12 and thus in the high draft semi-submerged
condition of the barge provide increased moment of inertia
of the water plane areas about the roll axis affording
improved stability characteristics about the roll axis,
-13- :
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.
.. , . ~ .. . .
~03 9~
particularly for a barge o~ the present type which has a high
length to width ratio as set forth her~inafter. While four
pairs of columns are illustrated, it is possible ~o use at
least three pairs of columns or more than four pairs of
columns, depending upon the desired stability and motion
characteristics and other design parameters; three pairs of
columns are minimum for such a pipelaying barge.
Referring now particularly to FIGURE 2, a pipeline
assembly ramp 40 is disposed along one side of platform P and
extends generally horizontally along the forward portion of
the barge while declining along the aft portion of the barge
!~ as indicated at 41 (see FIGURE 1) such that the ramp termin-
ates substantially at the stern of the barge at an elevation
3 corresponding substantially to the elevation of the second
deck 18 of platform P At the forward end of ramp 40 there
is provided a pipe section line-up station 42 for receiving
pipe sections from a transverse conveyor 44 which, in turn,
receives pipe section from a longitudinal conveyor 45 which
extends longitudinally parallel to ramp 40 along the inboard
side thereof. Sections of pipe are stored in discrete
longitudinally aligned pipe storage areas 48, a plurality of
:ri
such pipe storage areas 48 being spaced longitudinally along
the opposite side of barge 10 from ramp 40 and also spaced
~l along the longitudinal centerline of the barge. A plurality
`: of pipe support means 50 including pipe rollers are longitud-
inally spaced one from the other along ramp 40 for support and
. .
. .
-14-
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.: . . . - . .
~ 03~1~6~
movement of the pipe sections and pipeline to be laid. Between
such pipe suppor~ stations are a plurality of welding stations
51 for successively welding by any suitable known means the
joints between longitudinally aligned pipe section as the
pipeline is payed out from the barge. Further along ramp 40,
there is provided a plurality of longitudinally spaced
tensioners 52 each comprising upper and lower caterpillar-type
treads, rolls or equivalent means which engage and grip the
pipe to maintain a predetermined tension on the pipeline as
it is payed out from the barge (in a manner known in this ;
industry). Additional welding stations are located between
each longitudinally adjacent tensioner 52 and a final welding
station is loca~ed just aft of the furthest aft tensioner 52.
A plurality of additional pipeline supports 54 are longitud-
inally spaced along declining ramp 41 aft of the tensioners 52,
The pipeline supports 50 on the forward part of ~he barge are
preferably arranged vertically so that the pipeline section
carried by these supports lies along a substantially straight
line slightly upwardly inclined (in direction toward the bow
of the barge), at a suitable angle, e.g., on the order of ~wo -
degrees. A plurality of aft pipeline supports 55 are arranged
to support the pipeline section therealong a curve forming an ,~
initial portion of the pipeline overbend where the pipeline
curves downwardly for entry into the water. Additional pipe-
line work stations are spaced between tensioners 52 and
supports 54 and include x-ray and dope stations.
-15-
. . .
1~3 ~ 8
A helideck 56 is located at the forward end of the
barge and overlies the transverse conveyor 44, the forward end
of the longitudinal conveyor 46, and the pipe line-up station
42. Also illustrated in FIGURE 2 is a pair of anchor winches ;
57, which form part of an anchoring system, including additional
anchor winches, not shown, located adjacent the stern portions
of the barge. In a preferred form, the anchoring system
includes lO anchors and associated anchor lines, winches and
other ancillary equipment; and, as discussed more fully below,
such anchoring system enables three anchors to be set off each
bow quarter and two anchors off each stern quarter.
Along the side of the vessel opposite pipe laying
ramp 40, there is provided a gantry crane, generally designated
60. Transversely spaced tracks 62 are provided along
platform P, and these tracks extend longitudinally substanti-
ally the entire length of the vessel platform P, and thus
substantially the entire length of barge lO, as illustrated
particularly in FIGU~E 2. Gantry crane 60 includes a pair of
transversely spaced support trusses or legs 64, each being
mounted on a pair of longitudinally aligned trucks 66 at each ;~-
of its forward and aft extremities. Trucks 66 are engageable
with the rails 62 and gantry crane 60 îs thus movable longi-
tudinally along tracks 62 over substantially the entire length
of the platform P and barge and at least between longitudinal
positions adjacent each of the end columns 22. Gantry crane
60 also includes a rotatable cab 68, supported by trusses 64
-16-
:.~, . . . . .............................. .
, ~;: - : ,
1~3 ~(~6
and trucks 66, at the upper end of trusses 66, and cab 6
carries a crane boom 70 for rotating movement with the cab
about a substantially vertical axis by operation af power means
not shown, Gantry crane 60 is movable by suitable motors, not
shown, along tracks 62 to selected longitudinal positions along
barge 10 to perform lifting operations at such longitudinal
positions including the transfer of pipe sections from supply
boats to either the pipe storage areas 48 along platform P or
directly to the pipe transfer and line-up equipment 44 and 46
for loading pipe sections directly into the plpe assembly line.
Gantry crane ~0 is also useful for lifting operations in
connection with the stinger or other pipe transition element
generally designated T in FI~URE 1 and described below and for
general purpose lifting, transferring and setting of loads
about the barge, More particularly, the cab of gantry crane 60
is rotatable such that boom 70 overlies the barge or the one
side of the barge along which the gantry crane is mounted for
lifting operations off such one vessel slde and off either end
of the barge, depending upon the longitudinal location of the
gantry crane along the barge. Gantry crane trusses 64 straddle
the pipe storage areas 48 along the one side of the barge.
Thus longitudinal movement substantially the entire length of
the barge is not inhibited by the pipe sections stor~ in pipe
storage areas 48 and increased deck load and storage capacity
for the pipe sections are thereby achieved without impairing
operation and use of the crane at any longitudinal position
along the barge.
-17-
.
.
1039~
The gantry crane 60 can be located adjacent the stern end of
the platform P with the gantry trucks 66 locked to fix the
gantry crane 60 at such position and gantry crane 60 is a heavy ~ -
duty crane of such size ~nd capacity with cab rotatable about a
substantially vertical axis with boom 70 which is of such length
and capacity whereby gantry crane 60 is capable of performing
lifting operations for heavy loads off the end of the barge
adjacent which the gantry crane 60 is thus mounted and also off
at least the beam of the barge along which the gantry crane 60
is thus mounted. This would be done for example to service
the transition segment T extending from the stern of the barge
10.
As seen in FIGURE 6, hulls 12 are each di~ided into
longitudinally and transversely spaced compartment~ 76 forming
a plurality of ballast chambers for submerging and refloating
the barge; any suitable number of compartments 76 may be ~ ,.
provided as desired to perform the intended ballasting function,
While only the starboard hull and ballast system for same is
illustrated in FIGURE 6, it will be understood that the port
hull is similarly arranged and ballasted but on the opposite
hand. Ballast chambers 76 are selectively and independently
ballasted and deballasted whereby the hulls andlower portions
of the columns may be submerged with platform P remaining
substantially level throughout the submergence thereof and
any at~itude deviation of the barge in both heel and trim may
be corrected during change of draft between low and high draft
conditions and retention of the vessel in the high draft
condition. -18-
1 03~1~6 8
Ballast chambers 76 may also be selectively and independently ~ -
or dependently ballasted and deballasted when the barge is in
high draft semi-submerged pipe laying condition as described
below to provide a change in attitude of the barge about its
trim axis and thereby satisfactorily proceed with pipelaying
operations, particularly in conjunction and correlation with
gantry crane operations as below described. To these ends,
a plurality of conduits 77 extend from a pump room PR in each
of the hulls 12 in opposite longitudinal directions to the
several ballast compartments 76, there being multiple compart-
ments in the forward and aft portions, respectively, of each
hull. Pump room PR is provided with a sea suction inlet
indicated at 78 and an overboard disch~rge indicated at 79
controlled by suitable power o~erated gate valves 80 and 81
respectively, the hull side being indicated by the dashed lines
in FIG7~RE 6 A pair of pumps 82 and 83 are connected in
parallel via lines 84 and 85, respectively, across conduits 86
- and 87, conduit 86 connecting with inlet 78 and conduit 87 ~ :
connecting with discharge 79. Conduits 86 and 87 connect with
a conduit 88 and it will be seen that, with valves 89 and 90
closed, pumps 82 and 83 suction sea water through inlet 78
past suitable valves 9l located in the parallel pump lines 84
and 85, and into conduit 87 which, with valve 81 closed,
communicates with the main ballast conduit 92 which are
connected in parallel with ballast compar~ments 76 through a
pair of power operated valves 93 located on opposite sides of
-19-
. . . " . . .- , ,
-: ~ . -, . .
-; - . ~-: - . .
~: -: . - . .. ~ -
~3~
feed conduît 87, ballast conduits 77 each having a suitable
power operated valve 94, Thus, with valves 80 3 91 ~ 93 and 94
open and valves 81, 8g and 90 closed, the ballast compartments may
be simultaneously ballasted with sea water at an equal rate to
maintain the plat~orm substantially level when the hulls and
column portions are being submerged or the valves 94 may be
selectively operated to control the ballasting of the individ-
ual compartments 76 whereby the trim and/or heel of the vessel
may be corrected or altered during submergence or raising of
the vessel and especially in the semi-submerged high draft
condition during pipelaying operations, and particularly in
correlation to and adjustment of longitudinal movement, locat-
ion and/or load o~ the crsne 60 as hereinafter descri~ed, ~ine ~
88 is used to transfer ballast between one hull and the other.
Opposite ends of conduit 86 connect conduits 92
through suitable power operated valves 90 which the pumps 82
and 83 suctions, The pumps 82 and 83 discharges are connected
through valves 81 to the overboard discharge at 79.
To alter the draft of the barge from its high draft
condition to the low draft condition with the hulls 12 having
freeboard "f", valves 80 and 93 are closed a~d valves 81, 90
and 91 are open. Pumps 82 and 83 operate to pump water in
the same direction as before, and accordingly, suction from
conduits 92 via conduit 86 thereby suctioning ballast conduits
77 through valves 94 withdrawing ballast water from compart-
ments 76 ViR conduits 77, 92 and 86, the pump lines 84 and 85,
, ~ open valve 81 and outlet 79.
.','
-20-
~ -. , - - . .
. .
:: .
~039(~
With appropriate valves 94 open, compartments 76 may be deball-
asted as required to return the barge to its low draft
condition whereby the mean waterline with respect to hulls 12
is located along a line shown at llfll in FIGURES 1 and 7 so
that hulls 12 have freeboard above "f" in this low draft
floating condition Selected operation of valves 94 with
valves 81 and 90 open and valve 80 closed deballasts selected
compartments 76 as desired to alter the attitude of the vessel
about the heel and/or trim axis as necessary or desirable and
particularly ~o enable successful pipelaying operations as
hereinafter described. It is thus readily seen that compart-
ments 76 may be simultaneously ballasted and deballasted or
selectively ballasted and deballasted or have ballast trans-
ferred between the port and starboard hulls by selected
operation of the various valves and that this can be accompl-
ished when the barge is in any operating draft, for example,
in low draft floating condition with the hulls having freeboard
(i e. mean waterline at about "f" in FIGURES 1 and 7), semi-
submerged high draft floating condition, or any other inter-
mediate draft condition during barge operations, whereby the ~-
attitude of the barge about heel and trim axis can be altered
in such different draft conditions Note also ~hat the various
valves, conduits, etc. of the foregoing ballast system are
provided for each hull 12 whereby one or both hulls may be
: ballasted or deballasted alone or together or ballast trans-
ferred from one hull to the other -~
.,
-21-
~ 03 ~6 8
In the disclosed and described embodiment of the
present invention, the barge has an overall length of 400 feet
at hulls 12, with each hull having a beam of 34 feet, a height
of 20 feet and an inside spacing of 38 feet one from the other,
thus providing an overall hull beam of lQ6 feet between outer
sides of the two hulls 12, Thus, this embodiment has a length
to width ratio of about 4 to 1 and should have a length to
width ratio of at least 2,5 to 1, The height of the columns 22
is 23 feet. The centroids of the columns are equally spaced
39 feet from the vessel's longitudinal centerline. The pairs
of columns are longitudinally spaced one from the other 63.25
~eet with the bow pair of columns being spaced 19.75 feet from
the orward extremities of the hulls 12. The length of each
column is 46 feet and its width is 28 feet with the ends
thereof being formed cylindrical in shape providing an overall
column area of approximately 1119.5 square feet per column.
The light ship displacement of the vessel in low draft
condition is approximat~ 10,000 tons while the loaded displace-
ment in high draft condition is approxi-~ately 21,800 tons.
The weight of the gantry crane 60 may approximate 400 tons
unloaded and has a capacity for lifting heavy loads on the
order of 80 tons.
The pipeline transition segment T is releasably
secured to the stern of barge lG by a pivotal connection 74
and serves to support the "air length" portion of pipeline
"payed out" from the barge and extending between the stern of
-22-
;
1~35~Q68
the barge and the waterllne plus a portion of the pipeline
extending below the waterline, The pipel~ne transition segment
T may comprise one or the other of the "stingers" shown and
described in aforementioned U, S, Patent Nos, 3,704,596 and
3,685,305 the disclosures of which paten~s are incorporated
herein by reference as though fully set forth herein, .
Briefly, the disclosed pipeline transition segment
T is a column stabilized variable draft type stinger which
~ncludes a generally triangularly or rectangular shaped base
or hull structure generally designated 100 including a pair
of transversely spaced pontoons 101 and a depending keel 102, : :
pontoons 101 and keel 102 being arranged in triangular or
rectangular cross section and connected by suitable webs 103,
The forward end of hull 100 includes laterally spaced hinges
104 which cooperate with hinge structure carried at the stern
of the barge hull underlying the pipeline ramp whereby pipe-
line transition segment T is pivotally secured to barge 10,
Pipeline transition segment T also includes a plurality of
upstanding st~bilizing columns 105 secured to each of the upper
pontoons 101, the columns 105 being arranged in longitudinally
spaced pairs, A plurality of pipeline supporting carriages,
not shown, are mounted between the pairs of columns 105 and
include rollers disposed in a fore and aft direction along the
arc of the curve the pipeline will take in the overbend region
and enable translatlonal movement of the pipeline relative to
the transition segment T~
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.... . . ,. .. . ~
.:. . . ~ ; :-
~, ~. ,, .~ , , ,
;~ . . ~ . . ~ -
~03~06~ `
Referring to FIGURES 1, and 11 A-D and 12 A-C, the
pipeline transition segment T thus supports the pipeline
schematically shown at PL as it is payed out from the barge
in a manner such that the radius of curvature of the pipeline
portion indicated at PLC in said Figures is always greater than
the radius of curvature which would cause bending stresses ex-
ceeding maximum allowable bending stresses for the pipeline
and/or the protective coating generally applied to such pipe-
line. The pontoons lOl are compartmented to form a plurality
of ballast cham~ers which can be independently and dependently
ballasted and deballasted from the barge lO. The pipeline
transition segment T thus has the ballast capability to alter
its draft between a low draft pontoon supported condition and
a high draft semi-submerged floating condition wherein the
waterline lies intermediate or above the height of columns 105
and also to change ~he attitude of the pipeline transition
segment T about trim and heel axes by ballasting and/or de-
ballasting selected compartments in the pontosns 101.
Turning now to the embodiment of the pipelaying barge
illustrated in FIGURES 7-lO, the basic construction and config-
uration is like that of the previously described pipelaying
barge of FIGURES 1-6, but with several changes including: an
increase in vessel beam to provide increased deck-load capacity,
on the order of three times more deck-load capacity; an
~ncrease in the depth of the hulls and columns to provide
the necessary hydrostatic characteristics for such deck-load;
-24-
,. . ~ ;
.
.. ~ ,
~39~68
and modification to assemble and weld the pipeline along the
centerline of the barge rather tnan along a side, thus enabling
use of a symmetrical transition element T' (shown in FIGURE 10
for this embodiment) and minimizing effects of vessel roll on
the pipeline PL, Furthermore, this pipelayer barge embodiment
with centerline pipelaying feature also includes an inclined :
ramp so that the angle of entry of the pipeline into the water
is improved and the "air gap" segment of pipeline between the
barge stern and water line is much smaller thus enabling use
of a smaller and sometimes a simpler pipeline transition seg-
ment T' than would otherwise be necessary. Other differences
as between this and the previously described pipelaying barge
embodiment will become apparent from the following description
of this second embodiment.
Referring now to FIGURE 7, barge 110 includes a pair
of transversely spaced elongated hulls 112 extending in spaced
parallel relation and providing sufficient displacement to
support barge 110 in the low draft floating condition with
the hulls having freeboard whereby the mean water line is
along line "f" indicated in FIGURE 7. As in the previous
embodiment of FIGURES 1-6, the bow of each hull 112 is stream
lined to reduce resistance to towing when barge 110 is
en~irely supported in low draft condition on hulls 112, Each
hull 112 is substantially rectangular in cross section, as :
particularly illustrated in FIGURE 9, although the edges of
the hulls can be rounded and the sides arcuate and the hulls
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. . . ~
.
~, . . . . -
.. . . .
. . , .. .. ~ .
.; . . . .
1(339~ 8
otherwise specifically shaped as previously ~lescribed with
respect to the prior embodiment of FIGURES 1-6. The hulls 112
each have top and bottom substantially parallel and substanti-
ally planar surfaces extending su~stantially the entire length
of the hulls for reasons noted hereinafter.
A platform P' comprising a main deck 114 and a lower
deck 116 is supported a predetermined height above hulls 112
by support structure including a plurality of longitudinally
spaced, transversely extending truss formations generally
indicated 118 and a plurality of longitudinally spaced pairs
of transversely spaced stabilizing columns 120. A truss
formation 118 is longitudinally spaced between each longitudin-
ally spaced pair of columns 120 and the truss formation between
the longitud;nally spaced pairs of columns is similar to the
truss formation previously described in the prior embodiment
with respect to FIGURE 5. As illustrated in FIGURE 9, addit-
ional transverse truss formations 122 are locatod in the areas
between the hulls in transverse alignment with the longitudin-
ally spaced pairs of columns 120. This latter trussf~rmation
is similar to the truss arrangement illustrated in FIGURE 4,
Both truss formations in this embodiment (as in that of
FIGURES 1-6) also include horizontally transversely extending
cross braces joining the upper inner sides of hulls 112, one
to the other, to reinforce the structural relationship of the
hulls, platform and columns~ and to restrain the hulls against
lateral displacement.
-26-
,~ . . .
- ~ ,
.
1035~(~68
As in the previous embodiment, the support structure
also includes stabilizing columns 120 extending upwardly from
the upper surfaces of hulls lL2 to platform P' an effective
height which may be equal to and preferably greater than
the maximum anticipated wave height, i.e., the ver~ical
distance between wave crest and trough In this embodiment,
four pairs of columns 120 are equally longitudinally spaced
one from the other along hulls 112 with the column
arrangement on each hull being symmetrical with respect to the
other hull However, at least three pairs of such columns or
more than four pairs of such columns, longitudinally spaced
one from the other, may be utilized, with three such pairs of
columns being considered the minimum, as discussed above with
reference to the embodiment of FIGURES 1-6. As shown by the
dashed lines in FIGURE 8, columns 120 are preferably generally
oblong shaped with longitudinally elongated vertical sides
and semicylindrical fore and aft vertical end sections.
However, as discussed with reference to the embodiment of
FIGURES 1-6, such columns 120 may have circular, square,
octagonal or other cross-sectional configurations Columns 120
should be constant in cross-sectional area for that portion of
their height which extends from a point located 0 25 of the
column height above the top of each hull 112 to a point
located 0.75 of the column height above said hulls (or 0.25 of
the column height from the bottom of the platform P') Also,
as discussed for the embodiment of FIGURES 1-6, columns 120
-27-
10390f~8
preferably have constant cross-sectional area throughout their
height, but the section of the columns at the connect~ons
between the lower and upper ends of the columns with the hulls
and platform respectively may be varied to provide for
mechanical and structural interconnection providing such
different cross section does not have an adverse effect on the
hydrostatic and other operating characteristics of the barge.
This embodiment of pipelaying barge 110 is provided
with a pipelaying ramp 136 substantially along the longitudinal
centerline of the barge, along which a pipe assembly line
generally designated 138 is provided, Pipe storage areas 142
are disposed at various longitudinally spaced locations along
each of ~he opposite sides of the barge 110 on opposite sides
of pipe assembly line 138 and pipe sections may be transferred
from the pipe storage areas 142 onto longitudinally extending
conveyors 144 which flank the pipe assembly line 138 and which
conveyors 144 are adapted to transport the pipe sections
forwardly to pipe transfer and line-up equipment 146 located
at the forward end of pipe assembly line 138. The pipe trans-
fer equipment 146 includes transverse conveyors for transferr-
ing pipe sections from the long~tudinal conveyors 144
transversely of the barge into alignment with the pipe assembly
line 138 and the pipeline extending longitudinally therealong
and generally along the longitudinal centerline of the barge.
The pipe transfer conveyor 146 and the forward end of the pipe
assembly line 138 is carried on a cantilevered extension of
-28-
. . -
-
1~39~1~6~3 ~
platform P' which projects forwardly from the bow of the barge
(see FIGIJRES 7 and 8). Thîs cantilever extension also includes
a helideck 160 spaced above the pipe transfer and alignment
equipment 146. A plurality of longitudinally spaced welding :
statîons 147 are located along pipe assembly line 138 and
additionally between longi~udinally adjacent pairs of pipe
tensioners 148; any known suitable welding system may be used
at such station. Additionally, dope and x-ray stations are
located aft of the aftmost pipe tensioner 148. As will be
appreciated from a review of FIGI~RES 7 and 8, the ramp 136
includes a forward portion 150 of the main deck 114 and an
elongated central well 152. The lower surface 154 of well
152 inclines downwardly and ln an aft direction and provides
a support surface for mounting the tensioners 148 The well
152 communicates at the aft end of the barge with a tunnel 156
which exits from the barge between the aft pair of columns 120
and enables the pipeline PL to be discharged from the barge
at an elevation much closer to the waterline than possible
with prior embodiments such as that for FIGURES 1-6. Dope,
x-ray, and final coating stations are carried by a deck 158
which, in part, defines part of tunnel 156. As in the e~bodi-
ment of FIGURES 1-6, various pipe support means with rollers
(not shown) are spaced longitudinally along the ramp, with the
pipe support means located on the ~arge forwardly of the
tensioners supporting the pipe along a generally straight line
while the pipe support means located on the barge aft of the
tensioners 148 support the pipe along a genPrally downwardly
-29--
... ,.. .. . , . . . . . ~
,',' : , , ;: . . . . . ;
1~3 ~ 8
curved line. Also, as in the prior embodiment, the slope of
the straight portion of the pipeline is adjustable by adjust-
ment of the eleva~ion of the rollers, not shown, at each of
the pipe support means and preferably the straight portion of
~he pipeline is inclined upwardly towards the bow of the barge
at a desired angle, namely, about 3.5 degrees from horizontal
(see Angle B in F~GURE 7) to provide a good angle of entry of
the pipeline PL into the water including a good pipeline
curvature at pipeline segment PLC.
In this embodiment, a pair of gantry cranes 162 and
164 are mo~ted for longitudinal movement along opposite sides
of barge 110 on pairs of transversely spaced rails or tracks
166 which extend substantial;y the entire length of the plat-
form P' and barge 110. Gantry cranes 162 and 164 of this
embodiment are each similar to gantry crane 60 of the prev-
iously described embodiment of FIGURES 1-6; each such crane
includes lower transversely spaced longitudinally extending
trusses 168 which support a crane base or pedestal 170, the
lower ends of the side trusses 168 being supported on gan~ry
crane trucks 172 which engage tracks 166. Each gantry crane
162 and 164 includes a cab 174 rotatable on base 170 about a
generally vertical axis and carrying a boom 176. Referring
especially to FIGURE 9~ as in the gantry crane 60 of the
embodiment of FIGURES 1-6, each pair of crane side trusses
168 are transversely spaced one from the other such that the
side trusses straddle the pipe storage areas 142
-30-
. -
~(~3 9(~6 8
longitudinally spaced along each of the opposite sides of the
barge enabling longitudinal movement of crane 162 and 164
along tracks 166 for location at substantlally any longitud~
inal position along barge 110. It will be appreciated that
each gantry crane 162 and 164 has sufficient capacity and a
boom of sufficient outreach to perform lifting operations out-
board of the side of the barge on which the gantry crane is
mounted, as well as off either end of the barge depending upon
the longitudinal location of the crane along the barge. As in
the prior embodiment, the cranes are utilized for lifting
operations off one side and either end of the barge including
the transfer of pipe sections from supply boats onto the ;
storage areas 142 or directly onto the longitudinal conveyors
144 and for general purpose lifting operations aboard the barge
Each gantry crane 160 can be located adjacent the
stern end of the platform P' with the gantry trucks 156 locked
to fix either gantry crane 160 at such position, and each
gantry crane 160 is a heavy duty crane of such size and ~ .
capacity with cab rotatable about a substantially vertical
axis and with boom 176 which is of sufficient length and
capacity whereby such gantry crane 160 is capable of perform- ;
ing lifting operations for heavy loads off the end of the ~ :
barge adjacent which such gantry crane 160 is thus mounted
and also off at least the beam of the barge along which such
gantry crane 160 is thus mounted. This would be done for
example to service the transition segment or stinger T'
extending from the stern of the barge 110.
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, , , - ... - , - ,
.. . .
.. . .
ia~3906s
The hulls 112 of this embodiment of FIGURES 7-10 are
compartmented and ballasted and deballasted similarly as
described above with respect to e~bodiment of FIGURES 1-6. It
is believed sufficient to summarize here that such ballast
system has the capability to ballast the barge 110 between
low draft floating condition with hulls having freeboard and
semi-submerged high draft operating condition and can
selectively ballast and/or deballast any part of such ballast
system to alter the attitude of the barge about trim and heel
axes as desired and for the purposes set forth herein.
In a suitable pipelaying barge embodiment per FIGURES
7-10, the barge can have an overall length of 460 feet at
hulls 112, with each hull having a beam of 40 feet, a height
of 23 feet and an inside spacing of 50 feet one from the other
providing an overall hull beam of 130 feet between the outer
sides of hulls 112. The height of the columns 122 is 25 feet
so that tne height from keel to the underside of the platform
is 48 feet. In this embodiment, the barge has a len~h to
width ratio of ae least 2.5 to 1. The centroids of the columns
122 are equally spaced 50 feet from the vessel's longitudinal
centerline. The pairs of columns are longitudinally spaced
one from the oeher 128 feet with the bow pair of columns being
spaced 38 feet from the fon~ard extremities of the hulls 112.
The length of each column is 50 feet and its width is 30 eet
with the ends thereof being formed cylindrical in shape pro-
~iding an overall column area of approxima~ely 1706.5 square
feet per column.
-32-
~(39~:~6~
The light ship displacement of ~he vessel in low draft condi-
tion is approximately 12,000 tons while tne loaded displacement
in high draft condition is approximately 30,000 tons. The
weight of each gantry crane 162 and 164 may be approximately
400 tons and has a capacity for lifting loads up to about 80
tons The GM of this barge is about 4 feet
The pipeline transition segment T' may be a column-
stabilized stinger of such type as disclosed in U. S. Patent
No. 3,685,305 and particularly with respect to FIGURES 11-13
thereof, with the transition segment or stinger T' being
pivotally hinged to the stern of both hulls 112 as illustrated
in FIGURE 10 hereof Further description of the particular
transition segment or stinger T' is not believed necessary; it
i8 sufficient to note that such transition segment or stinger
T' includes a hull having a plurality of longitudinally and
transversely spaced ballast compartments which can be
selectively ballasted and deballasted to alter the draft of
the pipeline transition segment between high and 10W draft
conditions, and also to alter the attitude of the pipeline ~
transition segment T' about heel and trim axes as desirable `
and especially in trim to control the curvature of pipeline
segment PLC within desired limits.
For lifting, transferring and setting loads, in both
embodiments of the pipelay barge hereof, crawler-type cranes
without rails fixed to the platform may be utilized in lieu
; of gantry type cranes.
1: .. .
. . .
103 ~(?6 ~
Each crawler crane would include a ro~atable cab and boom
operable similarly as described above with respect to the
gantry crane in conjunction with the below described construc-
tional and operational features of the semi-submerged pipe-
laying vessels including correlation of ballast with crane
movement, location and/or load which is applicable to both
types of cranes when used in analogous manner.
In use, the pipelaying barge hereof is moved (by means
not shown) in a low draft floating condition with the hulls
having mean water line at "f" so the hulls have freeboard and
can be efficiently moved at speeds on the order of ~ to 10
knots providing the present vessel with high mobility for
transit between work sites located in different dis~ant
locations of the world The barge can be efficiently towed
by available tugs; or it can be provided with propulsion
machinery whereby it can move from site to site under its own
power, if desired. At the work site, the pipeline transition
segment is coupled to the pipelaying barge by the described
hinge connection, the transition segment being generally
towed or transported to the work site by a separate vessel.
In this connection, the crane or cranes on the pipelaying
barge are located adjacent the stern end of the barge to
connect the barge and pipeline transi~ion segment and/or
otherwise service the latter.
At the work site, the ballast compartments of the -~
barge 10 (or 110) and in the pipeline transition segment T
-34-
. . . .
~ O~ 9 O ~ 8
(or T') are simultaneously ~allasted to submerge their
respective hulls and pon~oons The barge 10 (or 110) is
ballasted so that the columns of the barge are submerged at ~ -
least 0.25 the height of the columns above the hull ~ops,
and pre~erably about 0.5 the height of the columns.
Referring to FIGURE 13, that is a graph showing ~he
permissible range of distance between the top of the twin ;
hulls 12 (or 112) of the pipelaying vessel 10 (or 110) and
the mean water line at "load line draftt' of the pipelaying
vessel in semi-submerged fLoating condition dependent on
varying column height, for construction and use of pipelaying
barges utilizing the present invention. "Load line draft" ls
the maximum permissible high draft position for such a pipe-
laying vessel, and FIGURE 13 shows along the ordinate the
distance from the top surface of the hulls 12 (or 112) to the ;~
mean waterline constituting permissible "load line draft" for
pipe laying vessels 10 (or 110) having different heights of
columns 20 (or 120) shown along the abscissa. An envelope
bounded by maximum and minimum curves designated A and B
constitutes the range in load line draft condition with
respect to given different column heights varying between a
minimum column height of about 20 feet and a maximtlm column
height of up to about 80 feet. The optimum operating draf~
for a given height colt~mn is also illustrated by the curve
designated at C within the maximum and minimum envelope curves
A and B.
-35-
-.. .. - .- .. ~ ~ ; ,
103~106f~
The location of ~he mean wat~r line above the vessel hulls 12
(or 112) and in relation to the height of the columns 20 (or
120) is determined according to the foregoing ~or the pipe-
laying barge 10 (or 110) when it is in semi-submerged high
draft floating condition for pipe laying operations. As
further amplified below, the columns of .he pipeline transition
segment or stinger T (or T') are thus submerged according to
extent of submergence of columns of the barge 10 (or 110).
Additionally, the pipeline transition segment T (or T') is
ballasted to establish its own trim angle to a desired angle
suitable for laying pipe of given size in the specified depth
of water with a predetermined configuration of curved pipeline
section PLC.
For most pipelaying operations, the trim of the
barge 10 (or 110) is set a predetermined trim angle to improve
the angle of entry of the pipeline into the water; and usually
the barge 10 (or 110) will be ballasted to provide a preset
operational barge trim angle within a range from 0 to 2 5
degrees from horizontal, and preferably about 1.5 degrees,
with the bow end of the barge tilted upward. When the barge
10 (or 110) is in semisubmerged column stabilized condition,
with the mean waterline above the hulls as herein described,
such columns provide righting moments about pitch and roll
axes ~o provide requisite barge s~ability consistent with
requisite motion-minimizing characteristics also
-36-
~039(~68
Particularly, the barge 10 (or 110) has a construction such
that the configuration and area of the columns and the number
of columns, and distances of the columns from the longitudinal
and transverse centerlines of the barge are such to provide
greater righting moment about the barge's transverse pitch
axis than the righting moment about the barge's longitudinal
roll axis when the barge is ln high draft semisubmerged
pipelaying condition, The substantially parallel planar top ~`
and bottom surfaces of the hulls as above described provide
mass damping when the barge is in high draft column stabilized ~ ~
condition; this inhibits vertical motion of the barge in heave, ;. :
and also inhibits net vertical displacement of the ends of the
barge due to angular motion ln pitch, Still further, when
the barge 10 (or 110) is in the high draft condition, the wave
action is only against the columns and the trusses and the
barge thus achieves substantial transparency to wind and
wave action. Further, minimized motion, with requisite
stability for the barge and pipeline transition segment combin-
ation according to the foregoing embodiments, also is
achieved by providing a low metacentric height ("GM"), for
example about 4 feet,
With the barge 10 (or 110) disposed in semi-submerged
high draft floating condition with mean waterline above twin
hulls 12 (or 112~ as above-discussed, the pipeline transition
segment or stinger T tor T') hinged to the stern will be
ballasted and submerged also as above-no~ed.
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103906~3
The column-stabilized stinger T (or T') is ballasted to
establish a suitable trim angle of the stinger T (or T') at
about 8-10 rom horizontal and tilted upwardly towards the
barge as diagrammatically illustrated in FIGURES llA to llD
and 12A to 12C Most o~ the columns of the disclosed stinger
T (or T') will be submerged below water line, generally except-
ing only the first and possibly also the second pairs of
stinger column(s) nearest the stern of the pipelaying barge
The geometrical construction of the stinger and location of
its pipe supporting rollers or equivalent means plus the angle
of trim of the stinger in relation to size, draft and trim
of the barge will determine the curvature of the pipeline
extending from the barge stern over the pipe supporting stinger
into the water and also to the sea bed at a given water depth.
When in high draft column stabilized condition for
pipe laying as above discussed, the natural period of the . :
pipelay barge and stinger combination in roll is between
about 25-30 seconds, in pitch about 20 seconds or more, and
in heave about 16 seconds
The motion responses of the pipelaying barge 10
(or 110) to wind and wave action are greatly minimized,
especially with respect to change in attitude of the barge
about its pitch axis as well as minimizing heave; this is
important in pipe laying operations and specifically because ;
the curvature of the pipeline segment PLC extending from the
vessel is highly affected by and sensitive to even small ~:
-38-
.. . . . . . .. . .
1(~3 9 O ~ 8
changes in the pipelaying vessel's angular disposition about
pitch and trim axes. Once the attitude of the pipelaying barge
about the trim axis is preset as above discussed, static trims
of such barge should be limited to less than plus or minus
one-half degree for the disclosed pipe laying arrangement.
Thus, the configuration, size and weight of the barge 10 (or
110) and its load distribution and especially the size,
configuration, area, location and resultant righting moment
of the columns about the pitch axis are designed in light of
this severe limit of angular change of the pipelaying barge's
attitude about the pitch axis
To lay pipe when the barge is in the high draft
column stabilized condition with preset operational trim, the
pipe sections carried by the barge in the pipe storage areas
are dlsposed onto the longitudinal and transverse conveyors
for assembly and connection one with the other along the pipe
assembly line. Particularly, the pipe sections are welded
one to the other and the pipeline is payed out from the barge
over the transition segment for entry into the water and final
disposition on the sea bottom The tensioners maintain a
predetermined tension on the pipeline as it is payed out and
~his, in conjunction with the transition segment, maintains
the pipeline curvature within allowable stress limits and at
or greater than the minimum radius of curvature. To pay out
the pipeline, the barge and transition segment are advanced
along the track of the pipeline along the sea bottom by
-39-
1039 0 ~ 8
hauling in the forward anchor lines and paying out the aft
anchor lines. In relatively shallow wate-îs and using consid-
erable lengths of anchor lines, the barge can be advanced in
this manner 3000 and 4000 feet before the anchors are
retrieved by anchor boats and reset
It will be appreciated that with the foregoing
described column stabilized barge and transition segment
arrangement, the pipeline is payed out from the aft end of
the barge at an elevation substantially above the mean
waterline, for example, on the order of 15-50 feet. The
transition segment thus supports the pipeline as it is
payed out from the barge for the air length of the pipeline
between the barge and the mean waterline and also a section
of the pipeline extending some distance in the water while
maintaining the curvature of the pipeline extending from
the tensioners on the barge within the permissible stress
limits and radius of curvature
As noted previously, the angle of trim of the barge
in semi-submerged high draft condition is a significant
factor in pipelaying operations as it affects the pipe ^~
curvature in the pipeline segment PLC extending from the aft
end of the barge. The pipeline extending from the barge
stern over the pipeline transition element into the water
and to and on the sea bed is somewhat "s-shaped" whereby the
pipeline first assumes a concave downward curve or "overbend" -~
as it is payed out from the barge end and over the transition
-40- ;
~ 039068
segment and then passes through a point of inflection at a
location beyond the stinger and has an intermediate section
which then extends to sea bottom and assumes a concave -;~
upward curve or "sagbend" as it is layed along the sea bottom `~
The pipeline is maintained as it is being ~aid within a ~-
suitable percentage of the stress yield point of the pipeline
for a given pipe as the pipeline is stressed in passing through
the "overbend","inflection point" and "sagbend". For a
given pipe, changes in the angular atti~ude of the barge
about the trim axis beyond certain narrow limits will cause
higher than allowable stresses which will break the concrete
coating usually applied about the pipe which is unacceptable
or will adversely overstress the pipe.
With respect to control of the attitude of the
vessel in trim about the pitch axis, it is desirable to set
a predetermined operational trim to improve the entry angle
of the pipeline into the water and the attitude and curvature
of the pipeline as it is payed out from the barge over the
transition element and disposed along the sea bottom As
previously noted, a bow-up operational trim is preferably set
by proper ballasting ofthe vessel prior to commencing
pipelaying operations; and, depending upon the pipe size and
water depth, a preset barge trim of 0 to 2.5 degrees, and
; preferably about 1.5 degrees, is set by ballasting the barge
as afore-described to alter its attitude to such a bow-up
trim angle. With such a preset trim angle of the barge,
~ -41-
. ., . : . .. - .
~ 3~ 8
a preset initial inclination of the pipeline of up to 10
from horizontal, but preferably up to 6 from horizontal bow-
upward may be used; che latter degree of pipeline inclination
from horizontal is the resultant of inclination of the pipeline
with respect to the barge plus angle of trim of the barge
about its trim axis With the barge in column stabilized
semi-submerged condition for pipe laying, any change in
attltude of the barge in trim should be maintained within an
angle not in excess of plus or minus about one-half degree
- 10 from the pre.set operational trim to avoid introducing a pipe
curvature in the overbend which would introduce stresses and
strains higher than allowable for the concrete coating about
the pipe or for the pipe itself That is, it is necessary to
maintain the attitude ~ the vessel in trim during pipe laying
operations within plus or minus about one-half degree of the
preset opera~ional trim which usually is within 0 to 2.5
degrees bow-up as discussed.
While the barge is designed to provide suitable
righting moments about the pitch axis as determined by the
configuration, number, areas and distances of the columns
from the pitch axis, the geometry ~ the submerged hulls and
lower column portions~ plus the weight distribution of the
barge, which would maintain the angle of inclination of the
barge about the pitch axis within plus or minus one-half
degree during operations and in response to dynamic forces, -~
i.e. wind and wave action, the pipe laying operation onboard
-42-
..... ,
~ . . i
~(~39(~68
the barge can and will introduce changes in the attitude
of the barge in trim exceeding plus or minus one-half degree
from the predetermined operational trim unless corrected.
For example, it has been found that the type, weight and
operation of crane or cranes used on the semi-submersible
pipelaying barge of this invention and the necessary longitud-
inal movement of the cranes, either loaded or unloaded,
introduces a significant change in the net moments about the
pitch axis which will cause a change in the barge's attitude
about the trim axis exceeding plus or minus about one-half
degree from the preset operational trim. More particularly,
it has been found that movement of a gantry crane 60 (or 160)
longitudinally along the barge platform P a predetermined
distance or greater will cause a significant change in the
angle of trim of the barge when the barge is in high draft
semisubmerged column stabilized pipelaying condition to such
extent that if i~ were not compensated for the attitude of the
barge about the trim axis would exceed plus or minus one-half
degree of the present operational trim For example, with a
pipelaying barge of the size and configuration illustrated
and discussed herein and mounting a gantry crane weighing on
the order of 400 tons for carrying loads of about 80 tons~
lo~gitudinal movement of the crane approximately one-quarter
of the length of the vessel causes a change in the angle of
trim of about one-half degree. The movement of such a gantry
crane longitudinally along the barge on either side of the
-43-
. ~ . .
. ................................... . .
103~6 ~
pitch axis, and also across the pitch axis, and the crane
location before and after such movement, even when the crane
is unloaded, thus becomes a significant factor a~fecting
maintenance of the requisite attitude of the barge about the
trim axis within plus or minus one-half degree of the preset
operational trim of the barge before such crane movement, To
compensate for the change in the angle of trim caused by
longitudinal movement of the crane along the platform and
thereby maintain the angle of trim of the barge within the
stated allowable small angle of change from the preset angle
of trim existing prior to longitudinal movement of the crane~
the barge 10 (or 110) is ballasted in response to and in ;~
correlation with longitudinai movement and location of the
crane or cranes so that the angle of trim change induced by,
during and after longitudinal movement of the crane with or
without load does not exceed plus or minus one-half degree
change from the preset angle of trim,
The foregoing is diagrammatically illustrated in
FIGURES llA-llD and FIGURES 12A-12C, in which drawings the ~-
angles and Figures discussed below are exaggerated for clarity.
In FIGURE llA, the barge 10 (or 110) is illustrated in a
horizontal position with 0 degree trim and a preset bow-up
trim of 8-10 for the pipeline transition segment or stinger T,
such attitudes of barge and stinger being accomplished by
approprlate ballasting as previously discussed, Referring to
FIGURE llB for the purpose of pro~iding a better angle of
`.
-44-
,. . . .
.
- . . .: . . :
.. ~ . . . . . - .. .... ... . . . .
... - . . . . . -
~139061~ `
entry of the pipeline into the water and to improve the
attitude and curvature of the pipeline being laid, the barge
10 (or 1103 is set at an attitude having a bow-up preset
operational trim angle of between 0-2.5 degrees, and preferably
1 5 degrees; and this is accomplished by selective ballasting
and/or deballasting of the hull compartments as above discussed.
The transition segment is also ballasted to maintain its own
desired trim angle relative to the barge and horizontal so as
to maintain the pipeline segment PLC within proper curvature
limits during all pipelaying operations. The discussed preset
operational t-im angle of the barge (for example 1 5 degrees)
is designated P.O.T in FIGURE llB which also illustrates a
representative crane C located adjacent the aft end of the
barge Longitudinal movement of the crane C, either loaded
or unloaded, from its position adjacent the aft end of the
barge shown in FIGURE llB for a certain distance, for example
approximately one-quarter of the length of the vessel, to a
location closer to the pitch axis, but with the axis of
rotation of the crane (designated by the dashed lines in
FIGURES llB and llC) still located on the aft side of the
pitch axis as illustrated in FIGURE llC, will induce a
change in the angle of trim of the vessel in excess of one-
half degree unless compensated for during movement of the
crane This is illustrated by the angle designated CMIT
(i.e., "crane movement induced trim") in FIGURE llC-, and in
this instance the foregoing described crane movement causes a
-~5-
.- ,
i~3 9 ~ ~ 8
decrease in the previo~lsly set bow-up angle of trim EO~.which
must be compensated for Consequently, for longitudinal move-
ment of the crane a distance which causes a change in the
vessel's trim angle exceeding one-half degree ~hange from the
prior set trim angle, ballast correction of trim is necessary
during and after the crane movement to counteract the
resultant induced angle of trim change and maintain the
attitude of the vessel close or equal to the preset operat-
ional trim, and in any event within plus or minus one-half
degree of the preset operational trim angle, consequently, the
ballast system and crane movement are correlated one with the ~ ~:
other such that the crane movement induced angle of trim is
offset or counteracted by ballasting. This is illustrated in
FIGURE llD wherein the actual operating angle of trim of the
vessel is illustrated close or equal to the predetermined
operating trim angle and in any event at least kept within
plus or minus one-half degree of the preset operational trim
before crane movement
It will be appreciated from a review of FIGURES llB
and llC that movement of the crane a like distance from the
position just aft of the pitch axis illustrated in FIGURE llC
to a location adjacent the aft end of the barge illustrated
in FIGURE llB would cause a similar change in the angle of
trim of the barge in the opposite direction. ~hat is, if the
preset operational trim is set with the crane located as
illustrated in FIGURE llC, movement of the crane aft to a
-46-
... . . :- , ~, .
..... . - , - .
.~ . .. : . .
.;., , . . . .
~039~6 8
location as illustrated in FIGURE llB would increase the
bow-up attitude of the vessel beyond the predetermined trim
angle and exceeding one-half degree unless compensated for to
counteract change ln trim angle during crane movement as
discussed. This is illustrated in FIGURE lls by the dashed
lines and angle CMIT'. This crane movement induced trim
change must be offset by ballast correction in the opposite
direction in order to maintain the barge attitude about its
trim axis within about one-half degree of the preset operating
trim, Such ballast corrections can be and are performed
simultaneously with movement of the crane or in increments
upon movement of the crane short distances thus enabling the
ballast system to catch up with and counter the change in
moment distribution caused by crane movement and avoid the
change in barge trim angle which would thereby result if not .
counter-acted as discussed,
A similar type correction is necessary when the
crane is similarly longitudinally moved along the forward
half of the barge, and also if the crane is moved similarly
longitudinally fore and aft of the trim axis. Referring to
FIGURES 12A-12C, the preset operational trim may be set with
the crane located slightly aft of the pitch axis as illus-
trated in FIGURE 12A. Movement of the crane forwardly to the
posi~ion shown in FIGURE 12B would change the attitude of
the vessel in excess of one-half degree from the present
operational trim (if not counter-acted) in this case inducing
-47-
``', , . ~ ,
- . . : ~ ,
~ ~3~68
a bow-do~ attitude designated CMIT in FIGURE 12B with respect
to the angle P.O,T. Consequently, ballast correction in trim
is necessary during such crane movement to maintain the barge
attitude within one-half degree of the angle P.O.T., and this
is illustrated ln FIGURE 12C which shows ballast correction
having been applied so that the crane movement induces a change
in angle ~ trim after ballast correction~ which angle is less
than plus or minus 0.5 degree from the angle P.O.T., designated
at CMIT in FIGURE 12C.
Following is a particular discussion of important ~:
features of t~e novel column stabilized semi-submersible barge
("SSB") and pipelaying combination including pipeline transit-
ion segment ("PLTS") with reference being made to all drawings
and description above, but with particular reference now made ..
to FIGURES 14A and 14E (plus FIGURES 13 and 1) which show and
identify particular features and terms defined and amplified
in numbered sub-paragraphs immediately following: :
(1) The length of the barge SSB along the barge
. platform P is designated by l'BLP", and along the
barge hulls by "BLH". The width of the barge
SSB across the platform P is designated by ''BWP'I,
and between the outside of the hulls by "BWH". ~.
The barge SSB is elongated whereby the ratio of
"BLH" to "BWH" is at least 2,5 to 1 and preferably
larger; and likewise for the ratio of "BLP" to "BWP".
~2) "CL" is total load of crane means C on the barge
(weight of crane with and without load3;
-48-
. , ~ . , ~ ;, :
.,, ,: . .
103 9 0 6 8
(3) I'TA" and "PA" is the locus of trim axis and
pitch axis of the barge SSB:
(4) "LC" is the locus and distance of total crane
means load "CLt in relation to barge trim axis TA
at beginning, during and cessation of movement of
said crane means C;
(5) "CLM" is the resultant moment about the barge
trim axis TA due to crane means load "CL" and its
locus "LC" with respect to the barge trim~axis
according to (4) above -- "CLM" varying in accord-
ance with variation of l'LCI' and/or ''CLI' per (2),
(3), and (4) above.
(6) "BCMP" are the righting moments of the barge
columns (22 or 120) about the axis TA (or PA) when
the barge SSB is in seml-submerged high draft pipe-
laying operational condition and counteracting "CLM"
per (5) above; and "BCMP" is the total of such
righting moments produced by the effect of the water
plane area of each barge column (22 or 120) called
"BCA" and the square of the distance of the centroid
of each such barge column waterplane area "BCA" from
the trim or pitch axis TA or PA, the latter distance
being called "BCAL". The aforesaid "BCMP" is
determined according to the following:
a) BCMP =[ [BCAx(BCAL) xKl]+K2 ] sin
wherein
_49_
. . .
.... . .. ... . .. ... : - -
1~39~)~ 8
(b) Kl is a constant which is a function
of the unde~ater geometry of the barge
SSB (10 or 110); and
(c) K2 is a constant which is a function
of the unde~ater geometry of the barge
SSB, the moment of inertia of each l`~
column about the column's own axis
"CTA" extending transversely ~ the
barge SSB and the we~ght distribution ;-~
within the vessel.
(d~ e is the angle of inclination of barge
SSB about the trim axis from the orig-
inal equilibrium position (see Fig.14C;
angle ~ is equal to "CMIT" discussed
on page 44 above).
(7) If crane induced moment "CLM" per (5) above in
typical operation of the crane means C over a frac- , :
tion of the total possible crane means travel
longitudinally of the barge SSB is such that CLM
exceeds the value of BCMP for aforesaid angle ~
equaling approximately 0,5 per (6) above, thus ; .
causing an angle of trim of barge SSB due to such
crane induced moment "CLM" absent counteracting
ballast per paragraph 8, 9, and 10 below (such angle
without such correction being called "BATC") to be
more than plus or minus about one-half degree change
-50-
. - . . ,
.. .. .. .. .. ... .
. , . ; - .. . . . .. .
. - . . . .. . . .
3~3~
in barge trim angle as compared to the preset angle
of trim "PAT" before said crane means movement per .
paragraphs (4) and (5) above.
(8) The described ballast means of barge SSB is ~ ~.
cperable in semi-submerged condition to c~ange the
angle of trim of said barge about TA and establish
"PAT" at a desired angle, generally about 0.0 to
2.5 degrees, and preferably about l.5 degrees, with
respect to the horizontal before movement of said
crane means C per (3), (4) and (5) above;
(9) The ballast means of barge SSB is operable in
semi-submerged condition between beginning and
cessation of movement of said crane means per (4), ~
(5), (6), and (7) above to limit the aforesaid
angle "BATC" so that change in barge angle of trim
"CMIT" defined above and shown in FIGURE 14C
is less than plus or minus about one-half degree
variation from the preset barge angle of trim "PAT". 1
(lO) "LCM" represents the limiting extent of
longitudinal movement of crane means C and crane
load "CL" in relation to barge platform length '~LP"
which is possible without ballasting to counteract
"BATC" whereas when '~CM" exceeds such limit said
ballast means ~s operated to limit '~ATC" and
maintain "C~T" within the limits stated in paragraph
(9) above.
-51-
; . . , .:,
. :
. . .
~ 1~3 ~6 8
(11) The barge SSB has columns (22 or 120) of such
height '~BCH" and the means for ballasting the barge
SSB is operable ~o raise it to a low draft condition
so that the twin hulls (12 or 112) have freeboard
and also operable to ballast the vessel to semi- :~
submerged high draft pipelaying condition such that
the defined and shown load line draft "LLD" of the
barge SSB in relation to height of the barge columns
"BCH" is within the limits of envelope curves A and
B of FIGURE 13 of this application and preferably
is according to curve C of FIGURE 13 of this
application.
(12) The minimum waterline above the top surfaces
of the hulls when the barge is in high draft semi-
submerged column stabilized operating condition is
represented by "MWLH" and is preferably equal to or
greater than 0,25 the height of the barge columns
"BCH" and at least eight feet,
(13) The pipeline transition segment PLTS in the
column stabilized semi-submerged operational condit-
ion of the barge SSB is adjusted about a transversely
extending axis in relation to the attitude of the
barge about its trim axis and to the horizontal
such that the curvature of the pipeline extending
from the barge end and over the pipeline transition
segment PLTS is controlled so as not to exceed
-52-
:: . . . . .
~ 035~68
allo~able stresses for the pipeline and its coating;
such adjustment to segment PLTS is made in conjunc-
tion with and correlated to operation of the ballast
means for maintaining the draft of the barge within
the stated limits and also maintaining barge trim
angle change "CMIT" less than plus or minus about
one-half degree variation from the preset angle of
trim PAT whereby the relative angular relation between
the barge SSB and pipeline transition segment PLTS is
substantially maintained throughout pipelaying
operations so as not to exceed allowable stress for
the pipeline and/or any coating which is applied to
the pipeline.
(14) Additional important features include: (a)
hulls having non-streamlined top and bottom surfaces,
for example, generally parallel planar top and bottom
hull surfaces, extending throughout substantially the
entire length of the hulls with each hull preferably
having a generally rectangular cross-section with
its longer axis extending in the direction of the
transverse centerline of the barge, with permissible
variations in the configuration of the hull sides
as discussed previously9 so as to provide increased
mass resistance to movement of the hulls through
water in a vertical direction when the barge lies in
-53-
,. . .
~ G~3~6 8
high draft column stabilized semi-submerged operating
condi~ion; (b) a plurality of longitudinally spaced
structural means reinforcing the structural relation-
ship of the hulls, pla~forms and columns, with such
structural means including substantially transversely
extending members structurally interconnecting the .
hulls adjacen~ the uppermost portions of the hulls and
restraining the hulls àgainst lateral displacement
relative to one another; (c) at least six columns
interconnecting the hulls and platform with three col-
umns upstanding from each hull and a pair of columns
located adjacent each of the bow and stern ends of the
barge, although one or more additional pairs of columns
may be provided, with four pairs of columns being
utilized in each embodiment of the disclosed barge;
(d3 also the area of the columns, the number thereof
and the distance of ~he columns from the longitudinal
and transverse centerline of the barge are such as to
provide a greater righting moment about the pitch axis
"BCMP" than the righting moment about the longitudinal
roll axis "BCM~" when the barge is in semi-submerged
high draft column stabilized operating condition;
'~CMR" is determined similary as above stated ;n
paragraph (6) with respect to BCMP except that the
distance of the centroid of each barge column water-
plane area is measured from the roll axis RA (or
heel axis HA) and the constant K2~S substituted for
the constant ~ n the formula stated in paragraph 6(a)
,, . , , . . :
lV3~68
above wllerein K2 s a constant which ls a function of
the underwater geometry of the barge, the moment of
inertia aE each column about the column's own axis
extending longitudinally parallel to the longitudinal
axis of the barge and the weight distribution within
the barge; and (e) each column should be constant in
cross-sectional area at least for the intermediate
portion of the column which extends vertically from
a point located 0.25 of the total column height
above the hulls to a point located 0,75 of the total
column height above the hulls (0,25 of the total
column height below the platform~.
It is noted that barge lO and llO include above
discussed means for ballasting to change the at~itude of the
barge about its roll axis RA when that should be necessary
or desirable.
It is noted that in prior column-stabilized twin
hull semisubmersible derrick barges used for pipelaying
utilizing the vessel arrangements disclosed in assignee's
aforementioned U, S. Patents No. 3,835,800, No, 3,685,305 and
No. 3,704,596 (as discussed earlier in this application)
all crane load during pipe laying operation is transferred to
the vessel hulls adj acent the stern at the same locus; hence,
there are no comparable conditions in ~such prior pipelaying
vessels as changing "LC" of crane load 1'CL", per above par (4)
.. - ,. . . .
:
l~P3~
or change in "CL~f" per above par (4), or changing "CLM" in
relation to '~CMP" and counteraction of ballast for adjustment
of '~ATC" to maintain "CMIT" per above paragraph (5) through
(10). [Said paragraphs being on pages 49-51 of this
specification.]
CLAIM TERM DEFINITIONS: The following designations
are used in the claims hereafter in the same way as they are
in above paragraphs numbered (1) through (13) above
with reference to the drawings [as stated in the paragraph
preceding said numbered paragraphs (1) through (13)]:
_ ____ _ _ ~
(1) through (13)]:
(a) "BLP" and '~LH" and '~WP" and "B~H" are
defined in said numbered paragraph 1. .
(b) "CL" and "C" are defined in said numbered
paragraph 2.
(c) "TA" is defined in said numbered paragraph 3,
(d) "LC" is defined in said numbered paragraph 4. :
(e) "CLM" is defined in said numbered paragraph 5. -~
(f) "BCMP" and '~CA" and "CTA" and angle ~ are
defined in said numbered paragraph 6.
(g) "BATC" and "PAT" and "CMIT" are defined in said
numbered paragraphs 7 and 9 and also in
paragraph 10 which defines "LCMn.
(h) "BCH" is the height of the barge's columns.
(i) "LLD" is the load line draft which is set forth
in F~GURE 13 in relation to column height and -~ :
shown in FIGURE 14A. ~ ~
.,',, "' '.,
-56-
~....... . .
. . - : -' .. ~ ~ , ' '
., . . ... . . . , . ;
39~:~6~
(J) "PAT" is ~he barge's preset angle of trim per
paragraphs 7 and 8 above and is provided by
selective ballasting and/or deballasting the
fore and aft ballast compartments as described,
above .
The invention may be embodied in other spécific forms
without departing from the spir~t or essen~ial characteristics
thereof. The present embod~ments are therefore to be con-
sidered in all respects as illustrative and not restrictive,
the scope of the invention being indicated by the appended
claims rather than by the foregoing description, and all
changes ~hich come within the meaning and range of equivalency
of the claims are therefore to be embraced therein.
~A
