Field of the invention

The invention concerns a ship or other vessel having launch-and-retrieval means, as set out by the preamble of claim 1.

Background of the invention

Ships used for long-line fishing commonly deploy (set) and retrieve (haul) the long-line through designated openings in the sides of the ship, on or above the ship’s main deck level. Long-lines may be very long, depending on the capacity of vessel, and comprise baited hooks at regular intervals. One disadvantage with this configuration is that the long-line is travelling through air for a considerable distance behind the fishing vessel before it enters the sea, and the exposed bait (or fish) attached to the long-line hooks attract sea birds. Particularly during long-line setting, the sea birds are thus

inadvertently hooked on the long-line and drown. This in an issue of great concern, particularly in Antarctic waters. One object of the invention is thus to reduce or eliminate the exposure of the long-line to sea birds during setting and hauling.

The prior art includes WO 99/22984 A2, which describes a central hauling pool for a fishing vessel. The central hauling pool comprises a generally vertical main tube through the vessel, with a lower opening or mouth towards the sea and an upper opening towards the atmosphere. The upper part of the main tube has a tube transition constituting a large relative widening of the cross-sectional area below the water line in the main tube to an upper tube part.

The prior art also includes WO 02/38439 Al, which describes a vessel for setting a long-line. The fishing vessel has a well or a mainly vertical, tube-shaped setting duct having an upper mouth or inlet for the long-line and extending down through the bottom of the vessel and having a lower exit portion for the long-line. The exit portion extends down below the keel or the bottom of the vessel.

The prior art also includes DE 89769 C, which describes a fishing vessel having a channel at the vessel bow. The channel E is of square or rectangular cross-section, and extends below the waterline and a short length into the ship. This channel may be closed by doors. The space underneath the channel is open to the water, while the space behind is divided into two outlets directed obliquely against the ship's walls.

The prior art also includes WO 03/059731 Al, which describes a trawling vessel for use with a trawl net for catching marine bio-resources. A trawl sack is attached aft on a trawl net for keeping the catch, and the vessel comprises lines for towing and hauling the trawl net. A lock chamber is provided in the vessel stem. The lock chamber has a main portion of its volume below the vessel’s design water line. The lock chamber is arranged for hauling the trawl sack with its catch from the sea, through a sluiceway in the stern.

Fishing vessels having interior pools are known in the art. It is also known in the art to pull lines and nets into, and release the catch in, such pools. However, the partly filled interior pools have a large free water surface, which tend to adversly affect the vessel’s stablility. As the pools typically are arranged in the vessels aft portion, the free-surface effect is particularly dominant about the vessel’s pitch axis, and may cause considerable vertical movements in the vessel’s aft portion.

The invention presents improvements to the prior art and offer other advantages.

Summary of the invention

The invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics of the invention.

It is thus provided a vessel, comprising a cavity defined by upper, forward and lateral wall members and having a first downward opening towards the water in which the vessel is intended to float; and a first gate device operable to selectively adjust the size of said opening, characterized by

- a plate member arranged in a lower portion of the cavity and extending between the lateral wall members and a distance in the cavity longitudinal direction, and

- an intake opening in a forward region of the cavity, forward of the plate member. A second gate device may be configured to selectively open or close said intake opening. The plate plate member may be a force member, shaped or arranged to generate a hydrodynamic force in the water

In one embodiment, the cavity is arranged aft of the vessel’s propeller and steering devices. The cavity may in one embodiment be part of a module arranged on the stern of a ship.

The vessel may comprise ballast tanks arranged on either lateral side of said cavity.

In one embodiment, the vessel comprises a conduit having a first opening at a deck level in the vessel and a second opening inside the cavity, preferably above a nominal water line (WL) in the cavity. Brief description of the drawings

These and other characteristics of the invention will become clear from the following description of an embodiment, given as a non-restrictive example, with reference to the attached schematic drawings, wherein:

Figure l is a side view, partly sectional, of a ship comprising an embodiment of the invented module;

Figure 2 is an enlarged view of the area“A” in figure 1, illustrating a configuration in which the aft gate is in a partially closed position;

Figure 3 corresponds to figure 2, but illustrates a configuration in which the aft gate is in a fully open position; Figure 4 is a plan sectional view at shelter deck (SD) level in figure 2;

Figure 5 is a plan sectional view at main deck (HD) level in figure 2;

Figure 6 is a schematic perspective view of a portion of a ship comprising an embodiment of the invented module (aft gate removed); the perspective being generally from below the ship and module. Figure 7 is a plan sectional view at main deck (HD) level, illustrating an alternative embodiment of the invention; and Figure 8 is a plan sectional view at a location below main deck (HD) level, as a further illustration of the embodiment of the invention illustrated in figure 7.

Detailed description of an embodiment

The following description will use terms such as“horizontal”,“vertical”,“lateral”, “back and forth”,“up and down”,’’upper”,“lower”,“inner”,“outer”,� ��forward”,“rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are used for the reader’s convenience only and shall not be limiting.

Figure 1 illustrates a vessel (ship) 1, for example a fishing vessel configured for long- line fishing. Connected to the ship 1 is a module 3, hereinafter also referred to as a launch-and-retrieval module. In the illustrated embodiment, the module 3 is connected to the ship afterbody 2, i.e. extending beyond the ship’s propeller and rudder 8. It should be understood that the module 3 may be retrofitted to an existing ship by attaching it to the ship’s original stern, indicated by the line S in figure 1, or it may be an integral part of the ship’s original hull.

Turning now to figures 2, 5 and 6, the launch-and-retrieval module 3 comprises a cavity 5 generally defined by upper walls or bulkheads 6, 6a, a forward wall or bulkhead 12, and side walls 13. In the illustrated embodiment, the upper wall 6 is arranged between the ship’s main deck level HD and shelter deck level SD, but the invention shall not be limited to this configuration.

Arranged in the lower part of the cavity 5 is a bottom plate member 11, extending between the side walls 13 and extending a distance in the cavity longitudinal direction.

A forward (in relation to the cavity) opening 9 is thus formed between the plate member 11 and a portion 2’ of the ship’s stem. A gate device 10 is arranged and configured to selectively open and close the opening 9, indicated by the double-headed arrow N in figure 2 (figures 2 and 3 illustrate a gate-open position). In the illustrated embodiment, the plate member 11 is shaped as a force-generating foil member, having a portion of increased thickness in the forward (upstream) region. But the invention shall not be limited to such shape, as the skilled person will understand that a hydrodynamic force may also be obtained by an (e.g.) flat plate member arranged an angle of attack with respect to the water flow. The plate member may therefore be referred to as a hydrodynamic force member, which may be arranged to provide an upward force when the vessel is moving in the water, thus serving to lift the vessel stem. The plate member may be fixed to the side walls 13 or may be movably connected to the side walls and configured to controllably rotate around a transverse axis.

Behind the plate member 11, the cavity 5 thus comprises an opening 7 which faces downwards and aft, towards, and exposed to, the water W surrounding the ship.

Seawater W is thus allowed to enter the cavity, forming a water line WL generally corresponding to the water line WL outside the cavity. The cavity opening 7 is in the illustrated embodiment controlled by main gate device 4. In figure 2 and figure 5, the main gate device 4 is in an extended position, thus defining a relatively small opening 7 in the bottom of the cavity 5. In figure 3, the main gate device 4 is in a retracted position, defining a large (e.g. full) opening 7 in the bottom of the cavity and towards the back of the cavity. Figure 6 illustrates how the opening 7, when fully open, extends anlong the module bottom and up into the module transom. In the embodiment illustrated in figure 3, the main gate device 4 is a linked, slidable gate which may be moved back and forth as indicated by the double arrow M. It may, however, have other shapes and configurations.

Figures 2 and 3 also illustrate a side opening 20, through which the buoys and long-line, e.g. floating line, may be hauled.

Figure 4 illustrates an access opening 17 leading from the shelter deck SD and down into the cavity 5, through which the long-line 19 may be hauled by means of winches 18. Referring additionally to figure 2, a chute (channel) 15 extends from shelter deck level SD and into the cavity 5 where it terminates in an opening 16 arranged in an upper portion of the cavity. In the illustrated embodiment, the chute opening 16 is arranged above the nominal water line WL. The chute 15 is configured for deploying (setting) long-line, indicated by arrow P in figure 2. The chute may also be configured for deploying protective devices (canisters) described by WO 2011/021946 Al.

Figure 5, which is a plan sectional view at main deck level HD in figure 2; illustrates how tanks 14 are arranged on both sides of the cavity 5. The tanks 14 may be used as fuel tanks, or as pure ballast tanks having means for selectively filling and emptying (not shown). The ship’s centre of gravity may thus be controlled by controlling the fluid volume inside the tanks, and the tanks may thus be used as trimming devices.

In use, when the ship 1 is moving forward (e.g. in transit voyage), the main gate device 4 and the gate device 10 are normally in the full open positions, whereby the forward opening 9 is open and allows water flow into the cavity 5 and through the opening 7 which in this state is fully open, i.e. in the bottom of the cavity and towards the back of the cavity. The bottom plate member 11 (which in the illustrated embodiment is foil- shaped as described above) may be configured or/and controlled to generate an appropriate trim force, depending on the external circumstances and desired operational parameters.

Similarly, in order to trim the ship, the opening 7 may be adjusted by controlling the position of the main gate 4, and/or the ballast (liquid) volume inside the tanks 14 may be controlled. It may for example be desirable to trim the ship such that the bow is raised when the ship is breaking ice or is sailing among ice floes. In general, arranging the invented module 3 on the stern portion of the ship, serves to move the ship’s centre of gravity aft, which may desirable. It should also be understood that arranging the force-generating foil or plate member 11 at a lower location than that shown in the drawings, may increase its efficiency. Arranging it farther aft will increase the moment arm.

During fishing operations, setting and hauling of the long-line are performed through the cavity 5. In this mode, the forward opening 9 is normally closed. The long-line is not exposed to the open and does therefore not attract sea birds that otherwise might get caught on the long-line. Also, the fact that the deployment chute opening 16 is arranged a distance above the nominal water line, provides for inspection and - if necessary - operator intervention during setting. The cavity 5 thus in effect provides a sheltered pool inside the ship. In addition, in combination with the above mentioned openings 9, 7 and plate member 11, it provides a stability-enhancing trimming device.

Referring now to figures 7 and 8, the module 3 comprises in an alternative embodiment internal bulkheads 30a,b that form a dividing structure 31 which extends from the forward bulkhead 12 and a portion into the cavity 5. This cavity-internal structure also divides the above-mentioned forward intake opening into first and second intake openings 9a, b, having corresponding first and second gate devices l0a,b. In this embodiment, the bottom plate member 11’ extends towards the aft portion of the module, formimg the adjustable opening 7 between plate extensions 1 la, 1 lb. In figure 8, the main gate device 4 is in the closed position, whereby the adjustable opening 7 is small.

For both embodiments, the plate member 11; 1 G, 1 la,b, serves to dampen the vessel’s pitch movements, particularly in the aft portion of the vessel. Model tests (in towing tank) of the vessel at transit speeds (13-14 kts) have shown a pitch reduction in the aft part of the vessel of approximately 40% when the module is installed, compared to the vessel without the module. Tank tests of the vessel at rest in the water (0 kts) have shown a reduction in wave height inside the cavity of appriximately 45% when the adjustable opening 7 is at its minimum, compared to the wave height at a full open state. Although the invention has been described with reference to a long-line fishing vessel, the invention shall not be limited to use on such vessels. It should be understood that the invention may have applications other than long-line fishing.

It should also be understood that the cavity may be arranged elsewhere in the ship’s hull, for example forward of the propeller and rudder.