WO2021112687A1

WO2021112687A1 - A buoy and a method for controlled feeding of a line connected to a fishing gear

Info

Publication number: WO2021112687A1
Application number: PCT/NO2020/050298
Authority: WO
Inventors: Rolf Knutsen
Original assignee: Active Fishing Buoys As
Priority date: 2019-12-03
Filing date: 2020-12-03
Publication date: 2021-06-10
Also published as: NO345744B1; EP4068958A1; NO20191428A1; EP4068958A4

Abstract

A buoy (1) and a method for storing rope connected to an underwater object such as a fishing gear, the buoy (1) comprises: - a spool (3) for storing at least a portion of a rope; - buoyancy elements (5, 5') being spaced-apart and rotationally rigid connected to the spool (3); and - at least one rotation control element, wherein a vertical buoyancy vector (BV) of the buoy (1), and a vertical mass vector (MV) are coaxial when there is no drag in the rope, and the buoyancy vector (BV) is closer to a centre axis of the spool than a resulting mass vector (MR) when the buoy (1) is subject to a drag (RD) in the rope exceeding a predetermined level, whereupon the buoy (1) repetitively capsizes and the spool (3) rotates accordingly, and the rope is unwound from the spool (3).

Description

A BUOY AND A METHOD FOR CONTROLLED FEEDING OF A LINE CONNECTED TO A FISHING GEAR

The present disclosure is related to a buoy for an underwater object such as a fishing gear. More specifically, the disclosure is related to a buoy for storing a line connected to a fishing gear such as for example a pot for catching fish and crustaceans, and fishing nets. Hereinafter, the line will also be denoted rope.

A report from the EU Commission named “Lost fishing gear - a trap for our ocean” states that 8 million tonnes of plastics go into the sea each year, among which a large amount of fishing gear. Each year about 20% of EU fishing gear is lost or discarded at sea, which indicates a total of 640.000 tonnes worldwide each year. The impacts on the environment are serious as regards for example animal welfare, chemical contamination that has dis ruptive effect on species, negative effect on human health due to toxicity in the food chain. Lost fishing gear has also great negative economical consequence for both fisheries and aquaculture sector, and the society in general. The invention disclosed herein, has for its object to reduce the amount of fishing gear that is lost unintentionally or accidentally. Two main reasons for loosing fishing gear uninten tionally or accidentally are: the fishing gear is transported by sea current to depths being greater than the rope connecting the fishing gear to the buoy; and the fishing gear is set in steep seafloor topography which results in the fishing gear sliding to larger depths result- ing in submerging of the buoy. Fishing gear lost in this way results in so-called “ghost fish ing” wherein the fishing gear may fish for several years.

Publication US 4,778,442 discloses a buoy for storing rope attachable to an underwater object such as a lobster pot. The buoy comprises a reel for carrying the rope. The reel is arranged rotatable inside a buoyancy element. When the lobster pot is thrown into the sea, the reel rotates inside the buoyancy element and feeds out the rope until the lobster pot lands on a sea bottom. When transported prior to use, the rope is stored on the reel within the buoy so that nuisance and danger of tangled ropes are eliminated. The buoy may be provided with a manually operated brake means to prevent the reel from rotating. Without engaging the brake manually, the reel is likely to rotate also when the buoy is subject to minor forces caused for example by wind and current. If the brake has been engaged, the rope is prevented from rotating for example if the fishing gear is set in steep seafloor topography resulting in the fishing gear sliding to larger depths.

The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art.

The object is achieved through features specified in the description below and in the claims that follow.

The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention.

According to a first aspect of the invention there is provided a buoy for storing rope con nected to an underwater object such as a fishing gear, wherein the buoy comprises:

- a spool for storing at least a portion of a rope wound around a perimeter of the spool, the spool having a longitudinal axis;

- buoyancy elements being spaced-apart and rotationally rigid connected to the spool; and

- at least one rotation control element, wherein a vertical buoyancy vector defining a buoyancy centre and the buoyancy of the buoy, and a vertical mass vector defining a centre of gravity and the mass of the buoy, are coaxial when there is no drag in the rope, and the buoyancy vector is closer to a centre axis of the spool than a resulting vertical mass vector when the buoy is subject to a drag in the rope exceeding a predetermined level, whereupon the buoy repetitively capsizes and the spool rotates accordingly, and the rope is unwound from the spool until the drag in the rope is reduced below said predetermined level, or until all of the rope is unwound from the spool.

By the term buoyancy centre is meant the centre of gravity of the water displaced by the submerged portion of the buoy.

By the term capsize is meant that the buoy is rotated by the drag in the rope from a first position of equilibrium wherein the vertical buoyancy vector are coaxial with the vertical mass vector, to a next position of equilibrium. Depending on a configuration of the buoy, the next position of equilibrium may be the same as the first position of equilibrium, or the next position of equilibrium may be different from the first position of equilibrium.

A rotational control element configured for capsizing only when subject to a drag in a rope exceeding a predetermined level, has the effect that the rope is unwound in a stepwise or gradual manner. This has the advantage that rope will normally not be unwound from the spool when the buoy is subject to water current and/or wind, and even small waves result ing in a temporarily drag in the rope that does not exceed the predetermined level result ing in capsizing of the rotation control element. This again has the advantage that the su perfluous rope is stored on the spool instead of being in or at a surface of the water. A superfluous portion of the rope floating in or at a surface of water may cause problems for a propeller of a surface vessel passing over the rope, or the rope may be cut by such a propeller. A cut rope is likely to result in lost fishing gear.

In one embodiment, the buoyancy elements of the buoy may comprise the at least one rotation control element. Thus, the rotation control element may form part of the buoyancy elements of the buoy. In one embodiment, at least a portion of the spool also forms part of the rotation control element of the buoy.

In one embodiment, the rotation control element is the buoyancy elements of the buoy. In such an embodiment the rotational control element provides a total buoyancy of the buoy. In another embodiment, the rotation control element and the spool provide a total buoyan cy of the buoy.

In still another embodiment of the buoy according to the invention, the rotation control element may comprise an orientation element configured for bringing the buoyancy ele ments in a specific position when the buoy is not subject to a drag in the rope, i.e. unload ed. Such an orientation element may be a weight element arranged in or on a portion of at least one of the buoyancy elements. Alternatively, or additionally, the orientation element may be an additional buoyancy means arranged protruding from a portion of at least one of the buoyancy elements.

In one embodiment, the orientation element is the spool.

In one embodiment, the orientation element may be adjustable with respect to weight or buoyancy. By adjustable is meant that the buoy may be provided with one or more weight or buoyancy means configured for adapting the force required for capsizing the buoy, to desired needs.

The buoyancy elements comprise two parts, each part preferably arranged at opposite end portions of the spool. This has the effect that the portion of unwound rope is stored between the buoyancy elements. The portion of unwound rope may therefore be protect ed by the buoyancy elements.

When seen perpendicular to the longitudinal axis of spool, the buoyancy elements may have a form selected from the group consisting of an ellipse, a trapezoid, a triangle, a rec tangle, and a quadrate. For buoyancy elements in the form of an ellipse, the stepwise capsizing and thus the unwinding of the rope depends on the largest dimension of the ellipse. Similarly, for a buoyancy element in the form of a trapezoid, a triangle, a rectangle, or a quadrate, the stepwise capsizing and thus the unwinding of the rope from the spool depends inter alia from a distance between the a centre axis of the spool and the “cor ners” of the buoyancy element. The larger the distance, the larger the drag from the rope is required to effect capsizing of the buoyancy elements. If each of the buoyancy elements are provided with substantially even thickness, the force required for capsizing the buoy ancy elements, and thus the buoy, depends only on the distance between the centre axis of the spool and the “corners” of the buoyancy elements.

In one embodiment, when the buoy is non-loaded, i.e. not subject to a drag from the rope wherein the buoyancy vector is coaxial with the vertical mass vector, a top portion of the buoyancy elements may be closer to each other than a bottom portion of the buoyancy elements being submerged. Tests have shown that such inclined rotation control ele ments, may have positive effect with respect to minimizing effect from wind and currents, especially for relatively slender rotation control element, and the visibility of the rotation control element.

As an alternative to provide the buoyancy elements having a form selected from the group consisting of an ellipse, a trapezoid, a triangle, a rectangle and a quadrate, the buoyancy elements may be formed as a circular disc or a polygon when seen perpendicular to a longitudinal axis of spool, or as a sphere. Preferably, a polygonal buoyancy element is a regular polygon having at least five side portions. However, such circular disc, polygonal, or sphere requires said orientation means in the form of a weight means, and/or in the form of a buoyancy means, arranged off-centre of the disc, polygonal or sphere in order to prevent free rotation of the buoyancy elements.

Preferably, the buoy may further be configured for being lifted out of water by applying a lifting force to a portion of the rope being unspooled from the spool, wherein, when the buoy is carried by the rope above the water, a resulting lifting force vector is closer to a centre axis of the spool than a resulting mass vector defined by the mass and position of the weight elements, the buoyancy elements, the spool and any rope stored on the spool, so that the buoy is prevented from rotating. This has the effect that the buoy may be lifted onboard a boat by for example hooking a portion of the rope being below the buoy, and bringing the rope and the buoy onboard the boat without unspooling any rope from spool during the lifting operation. This is advantageously when bringing the buoy onboard a boat having a relatively high freeboard.

In one embodiment, the spool may be non-axisymmetric. Preferably, a portion of the spool having the smallest radius faces the weight elements. This has the effect of optimizing the buoy with respect to as low mass of the weight element as possible.

In one embodiment, a cross-sectional area of the spool may increase from a centre por tion of the spool towards the buoyancy elements.

In a second aspect of the invention, there is provided a method for controlling feeding a rope from a buoy to a submerged object, wherein the method comprises:

- providing a buoy according to the first aspect of the invention,

- winding at least a portion of the rope onto the spool of the buoy,

- connecting an end portion of the rope to the object, and submerging the object.

Preferably, the method may comprise providing a buoy having a buoyancy capable of carrying the object above a sea bottom when all rope has been unwound from the spool. This has the effect that the buoy will not sink if the object, such as a fishing gear, does not rest on the sea bottom.

Alternatively, the method may comprise providing a buoy having a buoyancy being less than a gravity force from the submerged object being above a sea bottom when all rope has been unwound from the spool. This has the effect that the buoy will be submerged if the object, such as a fishing gear, does not rest on the sea bottom.

Preferably, the method may comprise providing a rope having a length being at least 20%, preferably 50% and most preferably 100% longer than a water depth at the intended loca tion of use. Thus, the likelihood for all rope to be unwound from the spool of the buoy is limited.

In the following is described examples of preferred embodiments illustrated in the accom panying drawings, wherein: Fig. 1a shows a perspective view of a buoy according to a first embodiment of the present invention;

Fig. 1b shows a buoy seen perpendicular to a longitudinal axis of the spool of the buoy, the buoy having similarities with the buoy seen in fig. 1a; Fig. 2a shows in a larger scale a rotation control element only, in a neutral position when not subject to a drag from a rope;

Fig. 2b shows the rotation control element in fig. 2a when subject to a drag from a rope prior to capsizing the rotation control element;

Fig. 3 shows in a smaller scale a perspective view of a buoy according to a sec ond embodiment of the present invention;

Fig. 4 shows a perspective view of a buoy according to a third embodiment of the present invention;

Fig. 5 shows a perspective view of a buoy according to a fourth embodiment of the present invention; Fig. 6a shows a perspective view of a buoy according to a fifth embodiment of the present invention;

Fig. 6b shows in larger scale a rotation control element provided with a slot for reg ulating a position of a spool;

Fig. 7 shows a perspective view of a buoy according to a sixth embodiment of the present invention;

Figs. 8a - 8d show a further embodiment of the invention, wherein the buoy is configured for being lifted by means of the rope out of the sea without rotating; and

Figs 9a - 9b show a further embodiment of the invention.

Positional indications such as for example right, upper, lower, refer to the position shown in the figures.

In the figures, same or corresponding elements are indicated by same reference numer als. For clarity reasons some elements may in some of the figures be without reference numerals. A person skilled in the art will understand that the figures are just principle drawings. The relative proportions of individual elements may also be strongly distorted.

In the figures reference numeral 1 denotes a buoy according to the present invention.

The buoy 1 comprises a spool 3 for storing at least a portion of a rope wound around a perimeter of the spool 3. When in use, the rope provides a connection between the buoy 1 and an object, such as a fishing gear typically in the form of a fish or crustacean pot, or a fishing net. The buoy 1 further comprises buoyancy elements 5, 5’ that is fixedly connect ed to the spool 3 in a rotationally rigid manner so that the spool 3 rotates when the buoy ancy elements 5, 5’ rotates. The figures show two buoyancy elements 5, 5’ spaced apart by means of the spool 3. It should be clear that in another embodiment (not shown), the buoy 1 may be provided with only one buoyancy element 5. In an embodiment wherein the buoy 1 is provided with disclosed herein, the spool 3 may be arranged between the single buoyancy element 5 and a buoyancy means known per se, such as for example a spherical buoy commercially available in the market.

The buoy 1 is configured so that a vertical buoyancy vector defining a buoyancy centre and the buoyancy of the buoyancy elements 5, 5’, and a vertical mass vector defining a centre of gravity and the mass of the buoy 1 , are coaxial when there is no drag in the rope, and the buoyancy vector is closer to a centre axis of the spool than a resulting mass vector when the buoy 1 is subject to a drag in the rope exceeding a predetermined level, whereupon the buoy 1 repetitively capsizes and the spool 3 rotates accordingly, and the rope is unwound from the spool 3 until the drag in the rope is reduced below said prede termined level, or until all of the rope is unwound from the spool 3.

In figures 1a and 1b, the buoy 1 comprises a first buoyancy element 5 and a second buoyancy element 5’ arranged at each end portion of the spool 3. The buoyancy elements 5, 5’ and the spool 3 is made in one piece from the same material. The material is select ed from a suitable material such as for example, but not limited to, polyethylene. The buoy 1 may be hollow or made from a foam.

In the embodiment shown in figures 1a and 1b, a buoyancy of the buoy 1 is the sum of buoyancy of the buoyancy elements 5, 5’ and the buoyancy of the spool 3.

As best seen in fig. 1a, each of the buoyancy elements 5, 5’ has a form of a trapezoid wherein a bottom portion is smaller than a top portion. This has the effect that buoyancy elements 5, 5’ tends to orient themselves, and thus the buoy 1, with at least a portion of the bottom portion submerged. Due to the form of the buoyancy elements 5, 5’ shown in figures 1a - 5, they serve the function of being rotation control elements of the buoy 1. In the following discussion of figures 1a - 5, the buoyancy elements 5, 5’ will therefore also be denoted rotation control elements 5, 5’.

In figures 1a and 1b the top portion of the rotation control elements or buoyancy elements 5, 5’ are closer to each other than a bottom portion of the rotation control elements 5, 5’ being submerged. In a prototype of such a buoy 1, tests surprisingly show that such in clined rotation control elements 5, 5’ has advantages with respect to reduced impact from wind and water current, while at the same time being easy to see for personnel being on a vessel. The reduced influence from wind may be explained by the reduced effective, verti cal area of the rotation control elements 5, 5’. Obviously, a “flat” rotation control element, i.e. a rotation control element having a portion above water level being small with respect to a surface area being submerged, will further reduce an influence from wind. However, such a configuration will have negative effect on visibility for personnel being on a vessel, and also a negative effect with respect to current.

In fig. 1a the spool 3 has an oblong cross-sectional area. A portion of the spool is provided with a reduced cross-sectional area. Although being relatively slender, a force from a drag in a rope has a relatively long arm thereby creating a relatively large turning moment or torque. A difference between figures 1a and 1b is the form of the spool 3 which in fig. 1b is provided with a circular cross-sectional area.

Figures 2a and 2b show a rotation control or buoyancy element 5 only. However, it is to be understood that the rotation control element 5 in a position of use, is connected to a spool mating with the aperture 35. The rotation control element 5 shown may form part of a buoy that may be provided with for example a spherical buoyancy means and a spool for mating with the aperture 35 of the rotation control element 5, or the rotation control element 5 may form part of a buoy 1 provided with two spaced-apart rotation control or element buoyancy elements similar to the embodiments show in for example figures 1a and 1b.

In fig. 2a the rotation control element 5 is in a neutral position in a water WL, a position being typical when there is no drag from a rope providing a turning moment on a spool. In such a neutral position, a vertical mass vector MV defining a centre of gravity and the mass of the buoy, are coaxial with a vertical buoyancy vector BV defining a buoyancy cen tre and the buoyancy of the rotation control element 5. In fig. 2b a spool (not shown) connected to the rotation control element 5 is subject to a turning moment from a drag in the rope, the drag indicated by arrow RD. The drag RD in the rope results in a tilting of the rotation control element 5, and the vertical buoyancy vec tor BV is moved to the right in the figure. If the drag in the rope continues while at the same time the vertical buoyancy vector BV is less than the resulting mass vector MR, i.e. the vertical mass vector MR being the sum of the mass vector MV and the drag RD form the line or rope, the resulting vertical mass vector MR will pass to the right of the vertical buoyancy vector BV, and the rotation control element 5 (and thus the buoy 1) will capsize and the spool 3 will rotate accordingly. Such a tilting and capsizing will continue until the drag in the rope is reduced below said predetermined level, or until all the rope is un wound from the spool. Thus, the buoy 1 repetitively capsizes and the spool rotates ac cordingly, and the rope is unwound from the spool until the drag in the rope is reduced below said predetermined level, or until all of the rope is unwound from the spool.

Figures 3, 4 and 5 show alternative embodiments of the buoy 1 according to the invention wherein each of the buoys 1 has a fixed design, i.e. the buoys have predetermined prop erties defined by the form of the buoyancy elements 5, 5’.

In fig. 3, the rotation control elements are in the form of rectangular prisms 5, 5’ being spaced apart by means of a spool 3 for storing at least a portion of a rope wound around a perimeter of the spool 3. In fig. 4, the rotation control elements are in the form of triangular prisms 5, 5’ being spaced apart by means of a spool 3 for storing at least a portion of a rope wound around a perimeter of the spool 3.

In fig. 5, the rotation control elements 5, 5’ have an elliptic form. The elliptic rotation con trol elements 5, 5’ are spaced apart by means of a spool 3 for storing at least a portion of a rope wound around a perimeter of the spool 3.

In figures 1a - 2b, and to some extent fig. 3, one 360 ° rotation of the spool 3 is a result of the buoy 1 being subject to repetitively capsizing four times. In fig. 4, one 360 ° rotation of the spool 3 is a result of the buoy 1 being subject to repetitively capsizing three times. In fig. 5, one 360 ° rotation of the spool 3 is a result of the buoy 1 being subject to repetitively capsizing two times.

T urning now to figures 6a - 9c showing various embodiments of the buoy 1 having disc shaped or spherical buoyancy elements 5, 5’. A buoy 1 having disc-shaped or spherical buoyancy elements 5, 5’ and a spool 3 arranged centrally with respect to the buoyancy elements 5, 5’ has a buoyancy vector BV that acts in a center of the spool. However, as will be understood from the description below, the buoyancy may still be adjusted.

Figure 6a shows cylindrical or disc-shaped rotation buoyancy elements 5, 5’ kept spaced- apart by means of a spool 3.

In fig. 6a, the buoyancy elements 5, 5’ comprises a rotation control element 6, 6’ config ured for bringing the buoyancy elements 5, 5’ in a specific position when the buoy is un loaded, i.e. no drag in a rope (not shown). Therefore, the rotation control element may also serve as an orientation element. The rotation control element may be provided by means of a weight element 6 (shown by solid line), by means of an additional buoyancy means 6’, here in the form of protrusions 6’ (shown by dotted lines) or even by means of a spool 3 being off-centre with respect to the buoyancy elements 5, 5’, as indicated in fig.

6b.

In one embodiment, the rotation control elements 6, 6’ comprises both weight elements 6 and additional buoyancy means 6’.

In fig. 6a, the buoyancy elements 5, 5’ comprises additional bores 7 provided with threads. A purpose of the bores 7 is to make possible adjustment of the rotation control or orienta tion element with respect to weight and/or buoyancy. The weight may be altered by re placing a first weight element 6 by a second weight element having weight being different from the first weight element 6, and/or by connecting an additional weight element 6 to another one of the bores 7. Similarly, an orientation element in the form of additional buoyancy means 6’ may be adjusted with respect to buoyancy effect and/or number of buoyancy means 6’. Thus, by altering the number or type of orientation elements, the rota tion control element of the buoy 1 is also altered. The properties of the buoy 1 can there fore be tailormade to for example a weight of a fishing gear.

Fig. 6b shows in larger scale a buoyancy element 5 provided with a slot 8 with a shoulder portion 10 for abutting against a head of screw 12. The slot 8 is configured for receiving a connection portion 3’ of a spool 3. The spool 3 is adjustable within the slot 8, from a centre portion of the buoyancy element 5 and towards a periphery thereof, as shown by dotted arrow, to provide a rotation control element. Again, the properties of the buoy 1 can there fore be tailormade to for example a weight of a fishing gear.

A spool 3 being off-centre with respect to the buoyancy elements 5, 5’ will, due to a spool mass vector, orient the spool 3 at a lowermost position with respect to a surface of the water if the buoy 1 is configured to keep the spool 3 raised above the surface of the water. In such a configuration the spool 3 provides a weight element 6’. If the buoy 1 is config ured to keep the spool 3 partially submerged when there is no drag in the line or rope, a spool buoyancy vector together with the spool mass vector will orient the buoy in a certain position. Thus, spool 3 being off-centre with respect to the buoyancy elements 5, 5’ is a weight element 6 and a buoyancy means 6’.

The spherical buoyancy elements 5, 5’ shown in fig. 7, may be controlled in a similar way as described with respect to fig. 6a. In the embodiment shown, a weight element 6’ is connected to an outer portion of the buoyancy elements 5, 5’ in the form of spheres.

In still another embodiment, the disc-shaped buoyancy elements 5, 5’ and spherical rota tion control elements 5, 5’ shown in figures 6a, 6b and 7, respectively, may be provided with weight elements arranged within a portion of the buoyancy elements 5, 5’. Figures 8a - 9c show disc- or cylindrical shaped buoyancy elements 5, 5’ provided with integrated weight elements 6’.

When collecting a fishing gear connected to the buoy 1 according to the invention, the rope may for example be hooked by a boathook and thereafter grabbed by an operator. If the spool still holds a length of rope, it is of great advantage if the buoy 1 is configured for being lifted out of the water by applying a lifting force to a portion of the rope being un spooled from the spool 3.

In the embodiments shown in figures 8a - 9c, the buoy 1 is configured for being lifted out of the water by applying a lifting force to a portion of the rope being unspooled from the spool 3.

Each of the buoyancy elements 5, 5’ comprises an integrated weight element 6’.

Fig. 8a is a view through A-A in fig. 8b and illustrates a rope 20 subject to a drag from a fishing gear (not shown) sinking towards the bottom of a sea. A buoyancy vector BV is at a center of the buoyancy elements 5, 5’. The buoyancy elements 5, 5’ are subject to a turning moment from a drag RD in the rope 20. The drag RD in the rope 20 results in a rotation of the buoyancy elements 5, 5’ as indicated by arrow R. If the drag RD in the rope 20 continues while the resulting mass vector MR, i.e. the sum of the mass vector MV and the drag RD form the rope 20, the resulting vertical mass vector MR has passed to the right of the vertical buoyancy vector BV, and the buoyancy elements 5, 5’ (and thus the buoy 1) will capsize with respect to a defined position wherein the buoyancy vector BV and the mass vector MV are coaxial, and the spool 3 (see fig. 8a) will rotate accordingly. Such a capsizing will continue until the drag RD in the rope 20 is reduced below said pre determined level, or until all the rope is unwound from the spool. Thus, the buoy 1 repeti tively capsizes and the spool rotates accordingly, and the rope is unwound from the spool until the drag in the rope is reduced below said predetermined level, or until all of the rope is unwound from the spool. Due to the drag RD in the rope 20 caused by the sinking fish ing gear, the buoy 1 is almost fully submerged with only a top portion being above a water level WL.

The situation discussed above with respect to fig. 8b, has some similarities with a flywheel wherein the “motor” is the drag RD in the rope 20.

In fig. 8c, there is substantially no drag in the rope 20 extending for example to a fishing gear that is resting on the bottom of a sea. The vertical buoyancy vector BV and the verti cal mass vector MV are coaxial and balanced by the deep-draught of the buoy 1 which is less in fig. 8c as compared with fig. 8b.

From the disclosure herein, it should be clear that the buoy 1 according to the invention provides a certain resistance against rotation when subject to a drag in a rope connected to the spool 3. Providing the spool with redundant rope with respect to an intended depth of use of a fishing gear, the buoy 1 will unwind rope from the spool 3 for example if the fishing gear is subject to an unintended sliding along a seabed slope, while at the same time the rope is kept substantially upright between the fishing gear and the buoy 1.

In fig. 8d the buoy 1 is carried by the rope 20 above the water WL. A lifting force vector RL is coaxial with mass vector MV defining a centre of gravity and the mass of the weight elements 6, the mass of the buoyancy elements 5, 5’, the mass of the spool 3 and any rope entwined thereon, so that the buoy 1 is prevented from rotating. This balancing of the lifting force vector RL is due to the weight elements 6 rotating an angle a with respect to its defined or “resting” position wherein the buoyancy vector BV and the mass vector MV are coaxial as shown in fig. 8c.

To prevent the spool 3 from rotating when the buoy 1 is carried by the rope 20 above the water WL, a mass of the weight elements 6 should be adapted to the spool 3 so that the lifting force vector RL does not have a greater distance from a centre axis of the spool than a resulting mass vector MR defined by the mass and position of the weight elements 6, the buoyancy elements 5, 5’, the spool 3 and any rope stored on the spool. It may be desirable to provide a buoy 1 having relatively small overall dimensions and having a weight being as low as possible.

From the discussion above with respect to fig. 8d, it should be clear that a torque from the weight elements 6 should be equal to or larger than a torque from the rope 20 carrying the buoy 1 above water WL. To obtain the desired feature of pulling the buoy 1 out of water without unspooling any rope from the spool, while at the same time providing a lightweight buoy, a torque from the rope 20 should be as low as possible, and the torque from the weight elements 6 should be as large as possible.

The inventor has surprisingly found that extremely effective lightweight buoy may be pro vided by providing a spool 3 being non-axisymmetric, wherein a portion of the spool 3 having a smallest radius, faces the weight elements 6. Further, the weight elements 6 are advantageously arranged at a perimeter of the buoyancy elements 5, as shown in figures 9a and 9b. Such an embodiment is also particularly effective with respect to the repetitive capsizing of the buoy 1 when an object such as a fishing gear is sinking toward the bottom of a sea.

Fig. 9a shows an embodiment of the invention wherein a cross-sectional area of the spool 3 increases from a centre portion of the spool 3 towards the buoyancy elements 5, 5’. Thus, the spool 3 comprises conical portions mirrored with respect to a mid-portion of the spool 3, while at the same time being non-axisymmetric. One effect of the conical portions is a reduced risk of an undesirable skewing of the buoy 1 when the rope is in a position close to or abutting against one of the buoyancy elements 5, 5’. A further effect of the con ical portions is related to a rope storing capacity of the buoy. The inventor has surprisingly found that when the rope 20 extends from a portion of the spool 3 being close to one of the buoyancy elements 5 or 5’, a major part of buoyancy vector BV is created by the buoyancy element being closest to the rope drag. To comply with the first aspect of the invention, i.e. the buoyancy vector BV being closer to a centre axis of the spool 3 than a resulting mass vector MR when the buoy 1 is subject to a drag RD in the rope exceeding a predetermined level, so that the buoy 1 repetitively capsizes and the spool 3 rotates accordingly, the spool 3 must have a certain diameter. However, when the rope 20 ex tends from an area of the spool 3 being at mid-portion between the buoyancy elements 5, 5’, the buoyancy vector BV is a result of the buoyancy of both buoyancy elements 5, 5’. Thus, a smaller diameter at a mid-portion of the spool may still comply with the required features. By reducing the diameter of the spool 3 at a mid-portion, the buoy 1 is capable of carrying more rope as compared with a spool 3 having an even diameter along a longitu- dinal axis of the spool 3. By utilizing this effect, the buoy 3 is more effective with respect to rope storing capacity.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodi- ments without departing from the scope of the appended claims. In the claims, any refer ence signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

C l a i m s

1. A buoy (1) for storing rope (20) connected to an underwater object such as a fish ing gear, the buoy (1) comprises:

- a spool (3) for storing at least a portion of a rope wound around a perimeter of the spool (3), the spool (3) having a longitudinal axis ;

- buoyancy elements (5, 5’) being spaced-apart and rotationally rigid connected to the spool (3); and

- at least one rotation control element, wherein a vertical buoyancy vector (BV) defining a buoyancy centre and the buoyancy of the buoy (1), and a vertical mass vector (MV) defining a centre of gravity and the mass of the buoy, are coaxial when there is no drag in the rope, and the buoyancy vector (BV) is closer to a centre axis of the spool (3) than a re sulting mass vector (MR) when the buoy (1) is subject to a drag (RD) in the rope exceeding a predetermined level, whereupon the buoy (1) repetitively capsizes and the spool (3) rotates accordingly, and the rope is unwound from the spool (3) until the drag in the rope is reduced below said predetermined level, or until all of the rope is unwound from the spool (3).

2. The buoy (1) according to claim 1, wherein the buoyancy elements (5, 5’) of the buoy comprises the at least one rotation control element.

3. The buoy (1) according to claim 2, wherein the rotation control element is the buoyancy elements (5, 5’) of the buoy (1).

4. The buoy (1) according to claim 1, wherein the rotation control element compris es an orientation element (6, 6’) configured for bringing the buoyancy elements (5, 5’) in a specific position when the buoy (1) is not subject to a drag from a rope.

5. The buoy (1) according to claim 4, wherein the orientation element is a weight element (6) arranged in or on a portion of the buoyancy elements (5, 5’).

6. The buoy (1) according to claim 4, wherein the orientation element is an addition al buoyancy means (6’) arranged protruding from a portion of the buoyancy ele ment (5).

7. The buoy (1) according to any one of claims 4 to 6, wherein the orientation ele ment is the spool (3).

8. The buoy (1) according to any one of claims 4 to 7, wherein the orientation ele ment is adjustable with respect to weight or buoyancy.

9. The buoy (1) according to claim 3, wherein, when seen perpendicular to the lon gitudinal axis of spool (3), the buoyancy elements (5, 5’) have a form selected from the group consisting of an ellipse, a trapezoid, a triangle, a rectangle and a quadrate.

10. The buoy (1) according to claim 9, wherein, when the buoyancy vector (BV) is coaxial with the vertical mass vector (MV), a top portion of the buoyancy ele ments (5, 5’) are closer to each other than a bottom portion of the buoyancy ele ments (5, 5’) being submerged.

11. The buoy (1) according to claim 5, wherein, when seen perpendicular to the lon gitudinal axis of spool (3), the buoyancy elements (5, 5’) have a circular form or a form of a regular polygon having at least five side portions.

12. The buoy (1) according to claim 11, further configured for being lifted out of water by applying a lifting force to a portion of the rope (20) being unspooled from the spool, wherein, when the buoy (1) is carried by the rope (20) above the water, a lifting force vector (RL) is coaxial with the resulting mass vector (MV) defined by the mass and position of the weight elements (6), the buoyancy elements (5, 5’), the spool (3) and any rope (20) stored on the spool (3), so that the buoy (1) is prevented from rotating.

13. The buoy (1) according to claim 12, wherein the spool (3) is non-axisymmetric.

14. The buoy (1) according to claim 12 or 13, wherein a cross-sectional area of the spool (3) increases from a centre portion of the spool towards the buoyancy ele ments (5, 5’).

15. The buoy (1) according to claim 1, wherein the spool (3) has a cross-section se lected from the group consisting of a circle, a polygonal, an ellipse, and rectangu lar with rounded corners.

16. Method for controlling feeding a rope (20) from a buoy (1) to an object to be sub merged, c h a r a c t e r i s e d i n that the method comprises:

- providing a buoy (1) according to any one of claims 1-15,

- winding at least a portion of the rope onto the spool (3) of the buoy (1), - connecting an end portion of the rope to the object, and submerging the object.

17. The method according to claim 16, wherein the method comprises providing a buoy (1) having a buoyancy capable of carrying the object above a sea bottom when all rope (20) has been unwound from the spool (3).

18. The method according to claim 16, wherein the method comprises providing a buoy (1) having a buoyancy being less than a gravity force from the submerged object being above a sea bottom when all rope (20) has been unwound from the spool (3).

19. The method according to claim 16, wherein the method comprises providing a rope (20) having a length being at least 30% longer than a water depth at the in tended location of use.