Note: Descriptions are shown in the official language in which they were submitted.
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ARTICULATING TUG BARGE HULL
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to shipping and in particular to an
arcticulated tug barge hull.
2. Description of Related Art
In waterborne transportation, one common method to transport cargo is
through the use of the barge. One method of providing propulsion to barges
is through the use of an articulated tug barge, commonly known as an ATB, in
which the tugboat is connected to a barge with pins, over which the tug can
rotate, as illustrated in Figures 1 and 2 at 10. In such prior art vessels,
the
barge 12 is provided with a notch or cutout 20 into the rear thereof. The
tugboat 14 is located within the notch 20 and connected to the barge 12
through the use of a horizontal pivots connections 22. Advantages of that
arrangement are that only a single tugboat is then required to provide
propulsion for the barge. Additionally, regulations commonly permit less crew
members to be located on such an articulated tug barge in comparison to a
similarly sized transport ships.
ATBs in current use may suffer from increased resistance when moving
through the water. In particular, conventional tugboat hulls are commonly
designed for use in open water whereas the notches in the barges commonly
have vertical sides, as illustrated in Figure 2. Such arrangement therefore
produces a substantial gap between the barge 12 and the tugboat 14, as
generally indicated at 16 in Figure 1. It will be appreciated that such gaps
will
produce turbulent flow therein, decreasing the efficiency of the combined
vessel and thereby requiring greater power and higher fuel consumption.
Additionally, as illustrated in Figure 1, conventional barges also commonly
include substantially squared or flat sterns having significant gaps between
the sides of the barge and the sides of the tugboat, causing further
resistance
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due to pulling water within the region to each side of the tugboat behind the
barge, as generally indicated at 18.
SUMMARY OF THE INVENTION
According to a first embodiment of the present invention there is disclosed a
ship hull comprising a first hull portion extending along a first centerline
and
having a leading surface and a second hull portion extending along a second
centerline and having a trailing surface. The ship hull further comprises a
pivot connection between the leading surface of the first hull portion and the
trailing surface of the second hull portion. The first portion has an outline
sized and shaped to be received within a corresponding cavity of the trailing
surface of the second hull portion with a substantially constant gap
therebetween.
The pivot connection may extend perpendicular to the first and second
centerlines of each of the first and second hull portions. The pivot
connection
may extend along a substantially horizontal axis transverse to the first and
second hull portions.
The leading surface of the first hull portion may have a substantially convex
cross section. The leading surface of the first hull portion and the trailing
surface of the second hull portion may extend substantially along an arcuate
path about the axis of the pivot. The leading surface of the first hull
portion
and the trailing surface of the second hull portion may extend along paths
between 98% and 102% of a radius from the axis of the pivot. The first hull
portion and the trailing surface of the second hull portion may extend along
corresponding arcs to each other to maintain a consistent distance
therebetween at all locations.
The leading surface of the first hull portion and the trailing surface of the
second hull portion may have a gap distance therebetween of between 12 an
36 inches. The trailing surface of the second hull portion may include a
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vertical portion along the arcuate path. The vertical portion may have a
height
up to 72 inches.
The first hull portion may have a width at least 90% of the width of the
second
hull portion proximate to the second hull trailing surface. The second hull
portion may include longitudinal side surfaces tapering towards the trailing
surface thereof. The side surfaces of the second hull portion may be coplanar
with corresponding side surfaces of the first hull potion. The first hull
portion
may have a width selected to be between 80% and 105% of a width of the
second hull portion. The second hull portion may have end surfaces adjacent
to the first hull portion. The end surfaces may have a width selected to be up
to 10% of a width of said second hull portion.
Other aspects and features of the present invention will become apparent to
those ordinarily skilled in the art upon review of the following description
of
specific embodiments of the invention in conjunction with the accompanying
figures.
BRIEF DESCRIPTION OF THE DRAWINGS
In drawings which illustrate embodiments of the invention wherein similar
characters of reference denote corresponding parts in each view,
Figure 1 is a top plan view of a prior art conventional articulated
tug barge
(ATB).
Figure 2 is a side cross sectional view of a prior art conventional
ATB as
taken along the line 2-2 of Figure 1.
Figure 3 is a top plan view of an ATB according to a first
embodiment of the
present invention.
Figure 4 is a side cross sectional view of the ATB of Figure 3 as
taken
along the line 4-4.
Figure 5 is a cross sectional view of an articulated tug barge according to
a
further embodiment of the present invention as taken along the
line 5-5 of Figure 4.
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Figure 6 is a side cross sectional view of the articulated tug barge
of Figure
3 as taken along the line 6-6.
=
DETAILED DESCRIPTION
Referring to Figure 3, an articulated tug barge (ATB) hull according to a
first
embodiment of the invention is shown generally at 40. The ATB hull 40
comprises a first hull portion 42 and a second hull portion 50. The second
hull
portion 50 includes a notch, generally indicated at 51 into which the first
hull
portion 42 is received. The first and second hull portions 42 and 50 are
connected to each other along a pivot connection 60 of any known type to
permit the first and second hull portions to pivot relative to each other
about a
pivot axis 62.
The first hull portion 42 extends between leading and trailing surfaces 44 and
46, respectively. Similarly, the second hull portion 50 extends between
leading (not shown) and trailing surfaces 52. As illustrated in Figure 3, the
trailing surface 52 of the second hull portion 50 forms the notch 51 into
which
the leading surface 44 of the first hull portion 42 is received.
Turning now to Figure 4, the leading surface 44 of the first hull portion 42
is
formed along a first radius 48 having its center at the pivot axis 62.
Similarly,
the trailing surface 52 is also formed along a second radius 54 having its
center at the pivot axis 62. It will be appreciated that in such industries, a
perfect radius bend is difficult and often a near radial curvature will be
provided. In practice it has been found that radii between 98 and 102% of the
designated radius will be acceptable. In such a manner, the leading surface
44 of the first hull portion 42 and the trailing surface 52 of the second hull
portion 50 form a gap, generally indicated at 100 therebetween. As each of
the leading surface 44 of the first hull portion 42 and the trailing surface
52 of
the second hull portion 50 are arcuate about a common axis 62, the gap 100
will have a substantially constant width therealong. In such a manner, the gap
distance 98 between the first and second hull portions 42 and 50 may be
minimized so as to prevent unwanted water turbulence from forming therein.
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The gap distance 98 will be defined by the difference between the radius 54
and the radius 48 and may be selected to be minimized while maintaining
proper clearances for operation in marine environments. By way of non-
limiting example, the gap distance 98 may be selected to be between 12 and
36 inches (305 and 914 mm) although it will be appreciated that other
distances may be selected depending upon the use and environment. As
illustrated in Figure 4, the second radius 54 may be larger than the first
radius
48 so as to be spaced apart therefrom at the top and bottom of the gap 100.
Furthermore, the second radius 54 may include a vertical portion, generally
indicated at 99 so as to permit accommodation between the relative draft
= between the first and second hull portions 42 and 50. In practice it has
been
found that a vertical portion of up to 72 inches (1829 mm) has been useful
although it will be appreciated that other distances may be useful as well.
With reference to Figure 3, the first hull portion 42 may have first side
surfaces 80 extending therealong. Similarly, the second hull portion 50 may
also have second side surfaces 82 exiting therealong. As illustrated in Figure
3, the first and second side surfaces 80 and 82 may be substantially coplanar
with each other so as to present a substantially constant surface to each side
of the gap 100.
As illustrated in Figure 3, the first hull portion 42 may have a first hull
width
indicated generally at 93 whereas the second hull portion 50 may have a
second hull width generally indicated at 91. The first hull width 93 may be
selected to be between 80% and 105% of the second hull width 91 although it
will be appreciated that other ratios may also be useful. Furthermore, as
illustrated the second hull portion 50 may include barge ends generally
indicated at 92 selected to be up to 10% of the second hull width 91 although
it will be appreciated that other dimensions may also be useful as well.
Turning now to Figure 5, it will be appreciated that in some embodiments of
the present invention, the first and second side surfaces 80 and 82 may be
offset from each other by an offset distance 84. In such embodiments, it will
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be preferable to maintain the offset distances to a minimum to provide a
reduced turbulence and drag behind the second hull portion 50. In particular,
the offset distance 84 should be maintained to be less than 5% of the width of
the trailing surface 52 of the second hull portion 50 so as to maintain the
width
of the first hull portion 42 as at least 90% of the width of the second hull
portion 50 proximate to the gap 100.
It will be appreciated that any sidewall profile between the first and second
hull portions 42 and 50 may be utilized. By way of non-limiting example, the
side edges therebetween may be substantially vertical, as illustrated in
Figure
6, although it will be appreciated that other profiles may be utilized as
well.
While specific embodiments of the invention have been described and
illustrated, such embodiments should be considered illustrative of the
invention only and not as limiting the invention as construed in accordance
with the accompanying claims.
