Note: Descriptions are shown in the official language in which they were submitted.
~ CA 02373462 2001-11-13
GR 99 P 8529 P O1
Description
Course-holding, high-speed, sea-going vessel having a
hull which is optimized for a rudder propeller
The invention relates to a course-holding,
high-speed, sea-going vessel having a hull which is
intended to hold payloads or passengers and at least
one rotatable, preferably electric, rudder propeller
(Pod) which is arranged gondola-like under the hull of
the vessel and has, to supply it with power, at least
one motor/generator unit which is arranged in the hull
of the vessel.
Vessels which correspond to the above are
known, for example from the field of cruise liners. The
known vessels are vessels with a keel structure in
which the rudder and the shaft system have been
replaced by one or more electric rudder propellers. The
actual shape of the vessel is essentially unchanged. An
example is presented in the publication "The SSP
Propulsor" from Siemens and Schottel,
No. 159U559 04982.
The object of the invention is to specify a
new, high-speed, sea-going vessel which has, in
contrast, an overall design which has been specifically
optimized for the use of electric rudder propellers to
make it possible, in particular, to exploit fully all
the possible advantages in terms of the utilization of
space, the handling characteristics, the resistance of
the vessel and the efficiency of the propulsion of the
vessel which can be obtained by using electric rudder
propellers.
The object is achieved in that the hull of the
vessel is designed so as to be adapted to the electric
rudder propeller drive both optimized in terms of
utilized space and also in terms of flow, for which
purpose the hull of the vessel mainly has a bottom
°
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which rises somewhat toward the two sides of the hull,
and in that the front part of the hull is designed so
as to stabilize the course and movement of the vessel
and ends under water, in particular in a relatively
slender bow with a bulb, and in that a flow-guiding
element (skegg) is arranged upstream of each rudder
propeller in order both to optimize the handling
characteristics and to achieve an optimized flow
against the rudder propeller, which has a displacement
volume for the water flowing against the respective
rudder propeller. This new design makes it
advantageously possible both to configure the useful
space in the hull in an optimized fashion and to obtain
stable course-holding and sea-going characteristics
with the smallest possible resistance of the vessel and
optimized drive efficiency. In particular, an increase
in useful space by significantly more than 10% and an
increase in the efficiency of propulsion by several
percent are achieved in this way. Thus, the
customer - shipowner or charterer - is provided with an
increased payload volume with reduced energy
consumption when operating the vessel. There is also
the option of traveling at a higher speed.
The introduction of the skegg which is
essential to the invention increases the wetted surface
of the body of the vessel. This known fact, which has
previously discouraged experts in the field from using
voluminous flow-guiding elements on the lower part of a
sea-going vessel to a relatively large extent, is,
however, surprisingly more than made up for by the
advantages, such as the increase in the propulsion
efficiency which is possible, and by the optimized low-
resistance outgoing flow in the stern area of the
vessel. Overall, the use of the skeggs according to the
invention provide for the vessel such great advantages
that they more than compensate for the disadvantage of
the greater wetted surface. This applies in particular
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to vessels which are driven by rudder propellers in a
multiple arrangement.
The vessel according to the invention disproves
the prejudices of experts in respect of the use of
voluminous underwater flow-guiding elements for sea
going vessels, in particular if the overall design of
the hull is optimized for the use of rotatable rudder
propellers, and said rudder propellers are
appropriately dimensioned and arranged. In this
context, it is particularly advantageous to use low
electric rudder propellers which permit particularly
favorable skegg designs (small skegg surfaces) and
whose shanks and motor housing can be included in the
optimization of flow.
In a refinement of the invention there is a
provision for the bow to be designed, in particular in
the lower part, with, in part, a concave profile. As a
result, it is very advantageously possible to select
an, overall, relatively full shape for the forebody of
the vessel without having to dispense with a course-
holding effect of the bow.
In a further refinement of the invention there
is provision that the flow-guiding elements (skeggs)
are hook-shaped at the end in the longitudinal
direction, preferably their design is matched to the
specific type of vessel and they have an outgoing flow
characteristic which gives rise to a decelerated flow
against the housing of the rudder propellers largely
free of separation. This results, inter alia, in the
advantageous possible increase according to the
invention in the efficiency of propulsion of the rudder
propellers, the rudder propellers themselves being
advantageously arranged and set, as a result of an
angular position in respect of the rising stern in a
vertical direction in respect of the bottom of the
vessel and the longitudinal direction of the vessel, in
such a way as to produce a further improvement in the
resistance-optimized outgoing flow of the rear part of
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the vessel and an increase in the propulsion efficiency
(skeggs).
There is provision here that the flow-guiding
elements (skeggs) are arranged bent toward the outside
on the bottom of the vessel, the angle being between 3°
and 10°, in particular approximately 7°. Together with
a design of the flow-guiding elements which is droplet-
shaped in cross section, a flow channel which is
designed so as to widen in the upward direction,
leading to a separation-free, decelerated flow against
the rudder propellers, is obtained. At the same time,
in general terms, a very good course-holding stability,
which is advantageously maintained even when there are
rolling movements, is obtained.
In a further refinement of the invention there
is provision that the flow-guiding elements, the lower
part of the hull and the bow are designed in terms of
shape and length so as to bring about a low-resistance
straight course of the vessel. Here, the flow-guiding
elements form an integral part of the hull, the skegg
parameters being as follows: on average the skegg width
is in the range 0.1 to 0.06 of the width of the vessel,
in particular approximately 0.08 of the width of the
vessel, the skegg depth is approximately in the range
1.0 to 0.74 of the draft of the vessel, in particular
approximately 0.92 of the draft of the vessel, and has
an offset with respect to the center of the vessel
approximately equal to the distance between the
respective propeller shaft and the center of the
vessel. The skegg length is advantageously between 0.25
and 0.38 of the length of the water line at the
designed draft, in particular approximately 0.32 of the
length of the water line at the designed draft. A skegg
is advantageously arranged in front of each rudder
propeller.
It is particularly advantageous that the skeggs
are designed as front vanes for the rudder propellers
if they approximately comply with the conditions
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specified above. Thus, the rudder effect is amplified
at small angles of the rudder propeller, and the vessel
reliably follows the rudder angles with the stern,
without significantly drifting in a lateral direction.
In a further refinement of the invention there
is provision that each rudder propeller has preferably
two individual propellers, in particular unidirectional
propellers, and that the propellers are arranged in a
directional overall outgoing flow of the rear of the
vessel, which leads to a decelerated oncoming flow in
the vicinity of the rudder propellers. This results
advantageously in a high level of efficiency of
propulsion by virtue of the combination of rudder
propeller and shape of the vessel.
In a further refinement of the invention there
is provision that by virtue of an arrangement of diesel
(gas-turbine) generator units behind the bow area the
hull is designed so as to run in a particularly
directionally stable fashion and, apart from the bulb
at the bow with its partially concave transition into
the shape of the front of the vessel and the skeggs,
does not have any flow-guiding elements. This results
in a good course-holding characteristic of the vessel
with a low-resistance flow around the vessel with a
simultaneously optimized outgoing flow at the stern.
In a further refinement of the invention there
is provision that the rudder propellers are arranged on
shanks which act as flow-guiding elements, are in
particular short, and have housings for the propeller
shaft which act as flow-guiding elements. This results
both in an optimized design of the useful space in the
vessel and also in good maneuverability.
There is further provision that the shanks and
housings of the rudder propellers are shaped in such a
way that, together with the flow-guiding elements on
the hull and the stern shape, they produce an end of
the hull which is optimized in terms of outgoing flow
and has low resistance. This optimization, which is
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achieved on the basis of towing tank trials, makes the
advantages of a vessel hull which is optimized for
drive by rudder propellers particularly striking. In
total, an increased level of propulsion efficiency
together with reduced vessel resistance are obtained.
There is provision that the abovementioned
optimizations are used in particular for hulls which
are designed for speeds of between 20 and 36 knots. At
such high speeds of a vessel, the previously unattained
course-holding stability in conjunction with the high
level of propulsion efficiency and the low vessel
resistance, in particular, are advantageous.
The design according to the invention of a
high-speed, sea-going vessel is of particular advantage
if it is designed as a Roro or Ropax vessel, the rudder
propellers being designed as low rudder propellers and
being arranged underneath the main car deck in such a
way that the main car deck can be designed so as to
extend from the stern to the bow. This results in a
specific optimization of the useful space for Roro or
Ropax vessels. The advantages achieved are of course
also obtained for container vessels or passenger
vessels.
The drives from the Siemens/Schottel Consortium
mentioned in the brochure mentioned at the beginning
can be configured as low rudder propellers without
major changes because they have a particularly low
hull/shank junction. Together with a slip ring
arrangement within the upper part of the shank and
rotary motors directly at the upper edge of the shank,
or else in the upper part of the shank, this results in
such a low overall height of the drive that the stern
of the vessel can be designed so as to be virtually
free of the influence of the drive on the inside. The
auxiliary units for the rudder propeller, such as the
hydraulic pumps, are arranged here essentially next to
the hull/shank junction so that a low bearing level for
entry ramps for vehicles etc. can be installed in the
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stern area. The main car deck can be arranged directly
above the rotary bearing of the low rudder propeller
and an access to the shank of the rudder propeller can
then be provided through a shank cover.
In one refinement of the vessel, there is
advantageously provision here that it has at least two
motor/generator units for the drive which are arranged
on the bottom of the vessel. This ensures good
stability of the vessel with an optimized car deck
arrangement. The space for the motor/generator units
with the associated control and switching devices is
arranged in the hull and bounded by bulkheads in such a
way that the SOLAS and IMO stability requirements and
the Stockholm Convention for sea-going vessels are
complied with. This results, according to the
invention, not only in a sea-going vessel which is
optimized in terms of space and consumption but also
which is particularly safe.
The invention is explained in more detail with
reference to drawings, it being possible to infer
further advantageous details which are essential to the
invention both from said drawings and from the
subclaims.
In particular:
FIG 1 shows the side view of a Ropax vessel which is
designed in accordance with the invention,
FIG 2 shows a cross section at the level of the
machine room through a vessel corresponding to
FIG 1,
FIG 3 shows a longitudinal section with a view of the
interior of the vessel and of the hull shape of
the vessel through a vessel corresponding to
FIG 1,
FIG 4 shows a section at the level of the second deck
through a vessel corresponding to FIG 1,
FIG 5 shows a section at the level of the first deck
through a vessel corresponding to FIG 1,
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FIG 6 shows the car deck with the loading ramp of a
different but similar vessel constructed in
accordance with the invention,
FIG 7 shows the weather deck of a different but
similar vessel which is constructed in
accordance with the invention,
FIG 8 shows a partial section through the afterbody
of a different but similar vessel in accordance
with the invention with integral skeggs, and
FIG 9 shows the linear outline of such vessels in the
skegg area.
In FIG 1, 1 designates the bridge of the
vessel, 2 designates the bow and 3 the bow bulb. The
weather deck 9, which can thus extend from the aft to
the fore part of the vessel, extends into the bow 2. At
a suitable distance behind the bridge 1 there is the
funnel structure 4 with the exhaust pipes, whose
arrangement can be selected relatively independently of
the current position of the diesel or gas turbine
generator units. Like the weather deck 9, the main
freight deck, for example a main car deck 10, is
designed so as to extend from the stern to the bow so
that these decks have a storage area extending from the
stern to the bow of the vessel. The short rudder
propeller 6, which according to the invention is
advantageously embodied here as a double rudder
propeller, is responsible for the fact that the main
car deck 10 is continuous even in the stern area. This
results in particularly small propeller diameters
accompanied by a good degree of efficiency. A skegg 8,
which, as shown, ends in a hook shape at a distance 7
in front of the rudder propeller 6, is arranged in each
case in front of the rudder propeller 6. The distance 7
is essential for a vibration-free flow against the
rudder propeller 6, it is therefore as a rule 1% of the
length of the vessel. 2 to 3% of the length of the
vessel are also advantageous. The underwater part 11 of
the vessel is designed so as to rise slowly in the
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stern area so that a largely eddy-free, low-resistance
efflux is produced in the stern area. Overall, with the
type of vessel according to the invention, the shape of
the bow and of the stern, the size and arrangement of
the rudder propellers and the skeggs are very
advantageously matched to one another in such a way
that the vessel moves with good course-holding
characteristics and at low resistance accompanied by a
high level of propulsion efficiency of the drive.
In FIG 2, 12 designates diesel generator units
with off-center exhaust-gas ducting. This produces
lorry loading tracks which can be configured in an
optimum way.
FIGS 3, 4 and 5 show machine rooms with
indicated diesel units 13, 17 and 21 at the bottom
center/front part of the vessel. As is apparent, the
small diesel or gas turbine units can be distributed in
such a way that a continuous main car deck is produced.
The precise installation location is selected, for
example in the center area of the vessel, in such a way
that favorable longitudinal mechanical stresses (smooth
water moment, transverse force profile) for the vessel
are obtained.
In FIG 3, 18 designates the main car deck and
14 the weather deck. In FIG 4, 20 designates converters
and transformers and 14 designates hydraulic units in
the stern. The hydraulic units in the stern are
advantageously arranged in a hydraulic room 15
approximately at the level of the upper edge of the
rudder propellers 16. These units therefore lie below
the continuous main car deck.
In FIG 5, 19 finally designates the skeggs,
which are directed rearward at this level and which
form an integral component of the underside of the
hull.
An advantageous design of the deck is shown in
FIG 7 (weather deck) and FIG 6 (main car deck). In
FIGS 6 and 7, the parking aisles for the motor
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vehicles, containers, etc. are designated by 24 and 25.
The entry ramp for the vehicles is designated by 23. As
is apparent, the design according to the invention
provides a larger number of parking spaces for vehicles
or containers than has ever been achieved before.
FIG 8 shows a cross section through the vessel
in the area where the skeggs start. Here, the lorries
on the weather deck are designated by 26. The lorries
on the main car deck are designated by 27 and the
lorries in the lower part of the vessel by 28. To carry
passenger cars, side deck tracks 29 which can be raised
and which can be driven onto from the main deck are
provided here. The front parts 30 of the skeggs are
integrated into the double bottom and its steel frame
and stringer system. The skeggs therefore form integral
parts of the structure of the vessel.
Finally, FIG 9 serves to explain the skegg
parameters, the skegg parameters being selected in
particular as a function of the type of vessel. The
skegg parameters are similarly varied, depending on
whether the vessel is a pure Roro vessel, in which only
a relatively low level of traveling comfort is
required, a Ropax ferry, a container or a passenger
vessel. The distance between the rudder propeller and
the rear edge of the skegg is also selected according
to these criteria because these are decisive for the
smooth running of the rudder propellers. The greater
the distance, the lower the transmission of vibration
by pressure pulses from the rudder propellers is to the
hull.
The pressure pulses from the propellers of the
rudder propellers to the respective shank and hull of
the vessel are, on the other hand, advantageously
influenced by technical control measures.
