METHOD AND DEVICE FOR USE ON TRAWLERS

Abstract: The present invention relates to a method and a device to be used when carrying out trawling using an engine-powered trawler (A) in order to prevent a trawl which is overloaded or has caught on an obstacle on the sea-bottom resulting in the loss of the trawler. In accordance with the invention, this is achieved by a specially designed, propellant-operated cutting tool (1-5) which is preferably operated from the trawler (A) bridge, cutting the steel wire which in nearly every case forms the connection between the trawler and the trawl. The invention also includes a specially designed, propellant-operated cutting tool (G1-15).

Description: METHOD AND DEVICE FOR USE ON TRAWLERS The present invention relates to a method and a device for use on engine-powered trawlers to prevent a trawl which is overloaded or caught on the sea-bottom causing the loss of the trawler. As the sorts of fish which are usually caught by trawling usually move in large shoals near the sea-bottom, there is always a risk that the trawl catches on an obstacle on the sea-bottom such as a wreck. Should this happen in severe weather, the result can be that the trawl simply drags the trawler down into the sea and such accidents do unfortunately occur. The only possibility of preventing such an accident is that one of the crew is in the right place at the critical moment and notices the danger and manages to release the trawl before it is too late. In the cold waters of northern latitudes and in bad weather conditions, it is almost impossible to always have a man on 'stand-by' at the trawl winch to prevent such an eventuality. Furthermore, it is usually the man on the bridge who first notices that the trawl is caught on the sea-bottom and that there is an immediate risk for the safety of the entire vessel. In heavy seas, it is also difficult to release the trawl sufficiently quickly when such an event does take place. Another conceivable near-accident which relates to the present invention, is the case where there is a risk that an overloaded trawl can overturn the boat when being taken on board. The present invention is intended to offer a solution to these safety risks in the form of a method and a device for the immediate, preferably remote-controlled, release of the trawl from the vessel should there be any risk of the near-accidents described above, in such a manner as to save the trawler without losing the trawl and the catch. At present, the trawl is usually operated using winches located on the aft deck of the trawler. While trawling is taking place, however, the load on the winches is relieved by means of a so-called 'halter' which consists of a steel wire the ends of which are secured on either side at the aft of the vessel, and which is stretched out in the form of a bow behind the trawler. The trawl cables are fixed to each other and to the halter at the halter centre point. During trawling, it is therefore the halter which takes up all the forces exerted on the trawl and for this reason, the winches can stand in neutral position. The trawl cables are secured to the halter by means of a special locking device which usually consists of a chain which is attached in a certain manner. A characteristic of this chain lock is that the steel wire of the halter is an important component and if this wire runs out of the lock, the trawl is released from being directly towed by the trawler as it is the halter which carries out this function while the trawl winches stand in neutral position. As the halter is secured to or is immediately adjacent to the stern of the trawler, an overloaded trawl represents a very great load on the trawler. Trawlers which are built to take on the trawl and catch over the stern rail are subjected to even greater loads and are therefore fitted with built-up aft loading supports to which the halter is secured. Stresses resulting from an overloaded trawl are extra large in the case of trawlers of this type as the stresses are exerted at a higher point on the vessel. This type of trawler, however, is advantageous regarding such operations as taking on board the trawl with its catch that operators do not wish to stop using this type of trawler and, in fact, such vessels will probably be even more common in the future. The present invention now offers a solution to the safety problems discussed above by proposing a method and a device for use on engine-powered trawlers to prevent trawls which are overloaded or caught on the sea-bottom resulting in the loss of the trawler. In accordance with the present invention, this is achieved when the trawl is caught on the sea-bottom by cutting the halter which relieves the load on the trawler's winches during trawling by means of a preferably remote-controlled, propellant-operated, specially designed cutting device which cuts near at least one of the halter attachment points or close to the stern of the trawler. The said cutting device is designed for this purpose to provide an immediate and clean cut at right angles through the steel wire halter. As the halter is cut at the same time as the trawl is heavily loaded, the halter wire runs out of the above-mentioned locking device upon which the device is immediately released and the trawl cables are freed to run out from the trawl winches which are in neutral position, and the immediate danger to the trawler is thereby eliminated and also the trawl is held closed which means that the catch is not lost as the trawler can easily turn and recover it. In certain cases, it can also be necessary to cut one or both of the trawl cables in a similar manner. The tool used for this purpose is of the same design. In order to carry out the above-described tasks it is necessary for the cutting tool used to provide a very rapid and in all cases, complete cutting of the steel wire which constitutes the halter, that the cutting operation does not result in fragments which could represent danger to people in the vicinity being cast out, that the operation is not experienced as disturbing by those in the vicinity and finally, that the cutting operation in all cases and even following a long period in the corrosive sea environment always functions when it is really necessary. In order to fulfil these stringent requirements, the cutting device in accordance with the said invention, has therefore been designed with a first longitudinal guide bushing which clasps the steel wire which constitutes the halter on both sides and which preferably at a right angle to the first guide bushing at the desired cutting point has a second guide bushing in which the actual propellant-operated cutting tool is located in order to reach the halter steel wire through the opening for this purpose. The second guide bushing with the adjustable cutting tool inside can be made completely sealed at manufacture while the parts of the first guide bushing which are not directly affected by the halter steel wire can easily be filled with grease or sealant. The said invention is defined in more detail in the patent claims below and a further description is now given in combination with the attached figures. The figures illustrate the following: Fig 1 a schematic arrangement during trawling while Fig 2 shows a cross-section side view of an example of the device in accordance with the said invention Fig 3 section DT-III in Fig 2 and Fig 4 a side projection of the actual device and Fig 5 and 6 the actual cutting device or surface in two projections. In the general layout during trawling shown in Fig 1, the trawler has the designation A, the two trawl winches B and C while the halter D has attachment points E and F and the wire cutting device G, which is characteristic of the invention is located close to attachment point F. Finally, the figure shows trawl cables H and J, and locking device K between halter D and trawl cables H and J. When the wire cutting device G is released, the halter D runs out of the locking device K and the trawl is freed from the halter which enables the trawl cables to begin to run out of the released winches B and C. The trawl, however, is still held together by locking device K. The more detailed view of the device in Figures 2-4 shows that the first guide bushing consists of an upper section 1 and a lower section 3. These are connected by means of a hinge 11. The steel wire halter 2 runs through this first guide bushing. The surplus space inside the guide bushing at the side of the steel wire can be filled with grease or sealant and the opening 15 through which the cutting device or axe 4 reaches the steel wire 2 can be sealed with a plastic plug 16. The second guide bushing 5 with its extreme end connected to a base plate 9, is firmly secured to the first guide bushing. The cutting device or axe 4 is adjustably attached inside the second guide bushing. The cutting device consists of a piston section 12 and a front cutting section 13 which has a finely sharpened bow-formed cutting edge 14. An opening 15 which is formed to accommodate the cutting edge and act as counter support and shearing edge is made for the cutting edge 14 passage in the first guide bushing and through the halter 2. As the cutting edge 14 is of bow form but does not form a complete circle, and because the opening 15 is designed in accordance with this, a guide is automatically formed which ensures that the edge is always at right angles to the halter. Fig 2 also shows the propellant charge 8 with its container 6, igniter 7 and igniter cable 10.

Claims: PATENT CLAIMS We hereby claim and desire to secure by Letters Patent the following. 1. Method to be used when carrying out trawling from an engine-powered trawler in order to prevent the trawler being dragged down into the sea by a trawl which is overloaded or which has caught on an obstacle on the sea-bottom w h e r e i n the trawl is released by the cutting by means of an propellant-operated, remote-controlled, totally encapsulated cutting device (G, 1-16) of at least one steel wire which joins the trawl to the trawler without causing the trawl to open. 2. A method as claimed in Claim I to be used when trawling using an engine-powered trawler (A) to prevent a trawl which has become caught in an obstacle on the sea-bottom causing the trawler to be dragged down under the water w h e r e i n a wire halter (D) the ends of which (E, F) are secured to each side of the trawler (A) stern and which during trawling operations relieves the trawl winches (B, C) used for operating the trawl and which during this operation are set in neutral as the outgoing trawl cables (J, H) from the winches (B, C) towards the trawl are secured to the halter (D) by means of a lock (K) which in the event that the halter (D) single attachment point (E or F) should rupture and the halter run out the trawl is immediately released from the trawler by means of an propellant-operated, totally encapsulated cutting device (G 1-15) preferably initiated from the trawler bridge. The cutting device is activated at one attachment point (E or F) of the halter (D) so that the halter (D) is cut at the stated attachment point (E or F) and so that the halter (D) can immediately run out of the said locking device (K). 3. A device to be used when trawling using an engine-powered trawler as claimed in Claims 1 and 2 in order to prevent a trawl which is overloaded or which has suddenly caught on an obstacle on the sea-bottom resulting in the loss of the trawler (A) due to being dragged down under the sea by the trawl by means of cutting the wire which joins the trawl to the trawler using a device initiated preferably from the trawler bridge w h e r e i n the said device incorporates a first guide bushing (1, 3) which encloses the location on the steel wire (2) where cutting is to be carried out together with the parts of the wire immediately adjacent and, at right angles to the first guide bushing (1, 3), a second guide bushing (5) in which an propellant-operated cutting tool (4) is adjustably located and which has a cutting edge (14) designed for this purpose which has access to the steel wire (2) which is to be cut via an opening (15) in the first guide bushing (1, 3) at which the edges of the opening function as counter support and shearing edge for the cutting tool edge (14), the cutting tool being designed with a remote-controlled propellant charge (8) positioned behind the said cutting tool. 4. A device as claimed in Claim 3 which is designed to cut a wire (D), a so-called halter, which during trawling relieves the load on the trawl winches (B, C) which are usually set in neutral while trawling is being carried out, by means of two trawl cables (H, J) from the winches being secured to the halter (D) by a locking device (K) in which the halter is incorporated and which is immediately released if the halter (D) runs out of the locking device as a result of being cut. 5. Device as claimed in Claim 4 w h e r e i n a cutting device has a bow-formed and finely sharpened cutting edge (14) at right angles to the halter steel- wire while the opening (15) in the first guide bushing is so designed that the cutting edge (14) can cut through the entire wire with a good margin. 6. Device as claimed in Claims 3-5 w h e r e i n the cutting tool between the cutting edge (14) and the propellant charge (8) has a piston section (12) which has a greater diameter than the cutting edge and where the cutting edge (14) is of bow form but does not form a complete circle, and where the opening (15) for the cutting edge in the first guide bushing (1, 3) is designed in order to guarantee that the cutting tool does not twist thus ensuring that the cutting edge (14) is always at right angles to the steel wire (2) of the halter. 7. Device as claimed in Claims 3-6 wherein the first guide bushing (1,3) can be opened by means of a hinge ( 11 ) so that it can easily be hooked over the halter steel wire (2) upon which the guide bushing parts can be locked together with the wire (2) between them.

Inventors: KARLSSON STAFFAN, KARLSSON ULF, KARLSSON, STAFFAN, KARLSSON, ULF
Applicants: SWETECH AB
Application year: 1997
Main classification: A01K73
IPC codes: A01K73, A01K75