[0001] The present invention relates to a method of maneuvering a smaller ship away from
a larger ship, wherein initially the smaller ship is located alongside and against
a larger ship and both ships have the same course and the same speed.
[0002] Such a method of maneuvering is typically performed in case of a pilot vessel which
sails alongside a sea-going ship in order to board a pilot. The pilot vessel is much
smaller than the ship to serve and has, generally, high maneuvering capabilities and
a high maximum speed in order to quickly serve many sea-going vessels one after the
other. The pilot vessel may have propulsion concepts as twin screws, water jets and
steerable propulsion.
[0003] The pilot vessel is maneuvered alongside and in most cases with its bow or midsection
against the sea-going vessel so that a pilot can board or disembark the sea-going
vessel. During this boarding or disembarking both ships have the same speed and move
in the same direction. After boarding or disembarking the pilot the pilot vessel proceeds
to a next vessel. A first known embodiment of the method for moving the pilot vessel
away from the sea-going vessel often requires that the pilot vessel diminishes its
speed until it is free from the sea-going vessel. This speed reduction takes time
and diminishes the effective use of the pilot vessel. In a second known embodiment
the pilot vessel has amidships a large fender between the pilot vessel and the sea-going
vessel and when sailing away from the sea-going vessel the pilot vessel rotates around
this fender with its stern to the sea-going vessel. This might lead to collision of
the stern of the pilot vessel with the side of the sea-going vessel, which is undesirable.
[0004] The present invention provides a method of maneuvering the smaller ship away from
the larger ship by means of changing the orientation of a bow rudder of the smaller
ship or activating a Magnus rotor at the bow of the smaller ship.
[0005] The method according to the invention overcomes the earlier described disadvantages
and appears to be highly effective to maneuver the smaller ship easily away from the
larger ship.
[0006] In case of the presence of a Magnus rotor at the bow of the smaller ship, a lateral
force on the front side of the smaller ship is created by activating it. An advantage
of applying a Magnus rotor is that its size does not increase upon activating it.
The Magnus rotor may be located within the circumference of the hull of the smaller
ship as seen from above and may remain there upon activating it. This minimizes the
risk of hitting the larger ship or any other obstacle during maneuvering.
[0007] It is remarked that using a bow thruster that ejects water sideways from the bow
of the hull of a ship does not function when the vessel has a more than minimal forward
speed. For maneuvering a smaller ship away from a larger ship that both have a forward
speed such a bow thruster has no use for steering the smaller ship away from the larger
ship.
[0008] The length of the larger ship may be more than three times larger than the length
of the smaller ship. This is typically a condition in which conventional methods of
maneuvering the smaller ship away from the larger ship is difficult.
[0009] For example, the smaller ship may comprise a pilot vessel and the larger ship may
comprise a sea-going vessel, which transports passengers or load between sea harbours.
[0010] The bow rudder or the Magnus rotor may project or is projectable below the bow of
the smaller ship in order to make the bow rudder or Magnus rotor more effective. Particularly,
smaller ships like pilot vessels sail in relatively deep water such that space below
the hull can be used for locating at least a part of the bow rudder or the Magnus
rotor.
[0011] In a preferred embodiment the bow rudder or the Magnus rotor is movable with respect
to the bow in vertical direction, since this minimizes the risk of a collision in
shallow water or getting stuck in a fishnet or the like. For example, the bow rudder
or the Magnus rotor may be movable with respect to the bow in vertical direction from
below the bow into the bow and vice versa. The Magnus rotor may be moved downwardly
along its longitudinal axis upon activating it and moved upwardly after the smaller
vessel has left the larger vessel. Alternatively, it may be moved downwardly and upwardly
by means of linkage bars. During maneuvering the smaller ship away from the larger
ship the rudder or the Magnus rotor can extend below the bow of the smaller ship.
[0012] The smaller ship may have a substantially vertical bow. This facilitates placing
of a bow rudder or a Magnus rotor and reduces the vertical movement of the bow in
heavier seas and ensures that the rudder or Magnus rotor remains immersed and remains
effective.
[0013] The invention will hereafter be elucidated with reference to drawings showing an
embodiment of the invention by way of example.
Figs. 1-3 are very schematic top views of two ships, illustrating an embodiment of
a method according to the invention.
Fig. 4 is a perspective view of a front side of a smaller ship in order to illustrate
an alternative embodiment of the method according to the invention.
Fig. 5 is a similar view as Fig. 4, but showing an alternative embodiment of the smaller
ship.
[0014] Fig. 1 shows two ships as seen from above. A smaller ship 1 is a pilot vessel and
a larger ship 2 is a sea-going vessel, for example a freight carrier. The dimensions
of the larger ship 2 are much larger than of the smaller ship 1. In the situation
as illustrated in Fig. 1 the first vessel 1 is located alongside the larger ship 2
and both ships have the same sailing direction and the same sailing speed. In this
condition a pilot may move between the smaller ship 1 and the larger ship 2. Generally,
the period of time during which the smaller ship 1 is located alongside the larger
ship 2 is as short as possible. After transferring staff between the ships, the smaller
ship 1 leaves the larger ship 2. Fig. 1 shows an initial situation in which both ships
have the same course and the same speed.
[0015] The smaller ship 1 includes a bow rudder 3. When it is desired to leave its position
alongside the larger ship 2, the orientation of the bow rudder 3 can be changed so
as to maneuver away from the larger ship 2. This is illustrated in Fig. 2. The bow
rudder 3 may have numerous shapes and dimensions. European patent
EP 2 040 978 shows several examples.
[0016] The new orientation of the bow rudder 3 causes a lateral force of the water onto
the bow rudder 3 near the bow of the smaller ship 1 in a direction away from the larger
ship 2 without first pushing the rear of the smaller ship 1 towards the larger ship
2. The effect is illustrated in Fig. 3. An advantage of controlling the bow rudder
3 in this situation is that at first a front side of the smaller ship 1 leaves the
larger ship 2 after which the back side thereof follows. In conventional cases, upon
using aft rudders it takes much more time to get the front side of the smaller ship
1 separated from the larger ship 2 or there is the risk that the rear side of the
smaller ship 1 collides with the larger ship 2.
[0017] Fig. 4 illustrates an alternative embodiment of the method according to the invention.
Fig. 4 shows a foreship 4 of the smaller ship 1. The foreship 4 has a bow 5 where
a Magnus rotor 6 is installed. When the smaller ship is upon leaving the larger ship
2 the Magnus rotor 4 is activated, resulting in a lateral force in a similar way as
with the bow rudder 3 as illustrated in Figs. 1-3. Fig. 4 further shows that in this
embodiment the bow 5 of the smaller ship 1 extends substantially vertically and the
Magnus rotor 4 is mounted in the bow 5.
[0018] Fig. 5 shows the foreship 4 of an alternative embodiment of the smaller ship 1. In
this case, the Magnus rotor 6 is extendable downwards with respect to the bow 5 as
illustrated by a double-headed arrow in Fig. 5. Upon activating the Magnus rotor 6
in order to leave the larger ship 2 the Magnus rotor 6 is moved downwardly along its
longitudinal axis. After the smaller vessel 1 has left the larger vessel 2 the Magnus
rotor 6 is retracted upwardly. In another embodiment the rudder or the Magnus rotor
can be moved from a compartment in the hull of the ship behind the bow 5 to under
or below the foreship 4 and the rudder or Magnus is activated when it is below the
foreship 4.
[0019] From the foregoing, it will be clear that the invention provides an improved method
for maneuvering the smaller ship away from the larger ship.
[0020] The invention is not limited to the embodiment shown in the drawings and described
hereinbefore, which may be varied in different manners within the scope of the claims
and their technical equivalents.
1. A method of maneuvering a smaller ship (1) which is located alongside a larger ship
(2) whereas both ships (1, 2) initially have the same course and the same speed, wherein
the smaller ship (1) includes a bow rudder (3) or a Magnus rotor (6) at a bow (5)
thereof and is maneuvered away from the larger ship (2) by means of changing the orientation
of its bow rudder (3) or activating its Magnus rotor (6), respectively.
2. A method according to claim 1, wherein the length of the larger ship (2) is more than
three times larger than the length of the smaller ship (1).
3. A method according to claim 1 or 2, wherein the smaller ship (1) comprises a pilot
vessel and the larger ship (2) comprises a sea-going vessel.
4. A method according to one of the preceding claims, wherein the bow rudder (3) or the
Magnus rotor (6) projects below the bow (5) of the smaller ship (1).
5. A method according to claim 4, wherein the bow rudder (3) or the Magnus rotor (6)
is movable in vertical direction with respect to the bow (5).
6. A method according to claim 5, wherein the bow rudder (3) or the Magnus rotor (6)
is movable between a position in the bow (5) and a position below the bow (5).
7. A method according to one of the preceding claims, wherein the smaller ship (1) has
a substantially vertical bow (5).
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only.
It does not form part of the European patent document. Even though great care has
been taken in compiling the references, errors or omissions cannot be excluded and
the EPO disclaims all liability in this regard.
Patent documents cited in the description