TRAWL WINCH FOR FISHING VESSEL

Abstract: A trawl winch for fishing vessels (1) comprises two cable drums (5, 6) with each its trawl cable (8, 9), said drums being coupled to a common differential (4) with differential lock and where the power input device of the differential which is connected to the drive engine (3) may be blocked. The trawl (2) is a conventional trawl with otter boards (10). The trawl winch moreover comprises a blocking means which may block the power input device to the differential (4). When trawling, the connection between the drive engine (3) and the differential (4) is locked so that the two drums (5, 6) will be freely rotatable, but in opposite directions. This means that the two cables (8, 9) will always be equally loaded.

Description: TRAWL WINCH FOR FISHING VESSEL The invention relates to a trawl winch for fishing vessels and of the kind described in the introduction to claim 1, preferably, but not exclusively, for stern trawlers. When a fishing vessel such as a stern trawler is trawling, it is important that the two trawl cables, the starboard and the port trawl cable, respectively, or cable pairs are equally loaded. Experience has proved that the trawl opening is greatest when the pull in the cables is equal, and maximum opening of the trawl will provide greater or faster catch. In some trawl winches the pull in the cables is mea¬ sured and one of the cables is then slackened or tightened to provide an equal pull in both cables, or there is applied a so-called split winch with auto¬ matic control of the wire pull. Alternatively, one endeavours in some other way by means of the drive engine or drive engines of the trawl drums to keep the pull in the trawl cables substantially equal. This requires energy and in some structures it is moreover necessary to assign a crew member to control the trawl winch and to adjust the pull during the en¬ tire trawling period which perhaps lasts 1/2 - 2 hours or longer. The energy requirement for control¬ ling the trawl winch is considerable and amounts by fishing for 20 hours per day to 19 litres of fuel oil per 100 h.p. of the vessel's propelling machinery. As an example, a stern trawler with 700 h.p. propel- ling machinery uses 133 litres of oil per day. Even if this does not sound of much, it will nevertheless exceed an amount of 100,000.- Dkr. by 300 fishing days in a year given fuel costs of 3 Dkr. per litre. The object of the invention is to provide a trawl winch which may in the usual manner be used for let¬ ting out and hauling in trawls but which will use no energy during the trawling while always ensuring an equal pull in the trawl cables. This is achieved by designing the winch according to the invention as further disclosed in the character¬ ising part of claim 1. When the power input device of the differential is blocked, for example by the drive engine, the two drums may freely rotate but in oppo¬ site directions. When one of the drums slackens the cable, the other drum will accordingly tighten its cable and vice versa. This means that the total pull of the trawl is transmitted to the two cables with exactly half the pull on each cable. Especially when turning where the load on the inner cable lessens considerably - by trawling on a sea floor slope where the pull would otherwise be quite unequal resulting in a small trawl opening - it is highly advantageous quickly, fully automatically and without extra energy consumption always to have an equal pull in the two cables. If one of the otter boards gets stuck in the sea floor, the other one will move forwards at double speed but: the extra load will be distributed by half the load in each cable thereby avoiding damage to "the fishing tackle before bringing the vessel to a stop. By conventional trawl winches, where the drums are braked on band brakes, the entire load will be trans- itted to the cable on the stuck otter board. The hauling in of the trawl with the winch according to the invention is performed by activating a dif- ferential lock so that the drive engive will transmit the same moment to the two drums. In this way it is possible to let out and haul in the trawl in the usu¬ al manner. By designing the trawl winch according to the inven¬ tion as further disclosed in the characterising part of claim 2, it is simple to arrange the blocking be¬ tween the drive unit/drive engine and the differen¬ tial. The blocking means may be designed so as to be manoeuvrable electrically, hydraulically or mechani¬ cally, for example in such a manner that it may be activated from the wheel house. The blocking means may also be executed in a quite simple manner, parti¬ cularly for small vessels, so that it merely consists of a manually operated arm which blocks the power in¬ put device of the differential. Claim 3 discloses a particularly advantageous embodi¬ ment of a very compact design of the trawl winch ac- cording to the invention. Claims 4 and 5 disclose practical and reliable de¬ signs of the differential. It is essential that a trawl winch is stongly and reliably structured so that it may stand the tough working environment on the sea. The invention will now be further described in the following with reference to the drawing showing an embodiment of the invention wherein Fig. 1 schematically shows the principal structure and function of the invention, and Fig. 2 shows an example of a mechanical embodiment of the trawl winch according to the inven¬ tion. In Fig. 1 of the drawing the stern of a vessel is shown schematically and is designated 1. On the ves¬ sel there is arranged a trawl winch with two cable drums 5 and 6 which through a differential 4 are pul¬ led by a common drive engine or motor 3 which may be any type of engine or motor, such as an electric mo¬ tor, a hydraulic engine or a combustin engine. From each of the cable drums 5 and 6 the trawl cables 8 and 9 extend through each its block 7 to the trawl 2 which in the usual manner is manoeuvered by two otter boards 10. When the trawl is set and the vessel 1 pulls the trawl 2, the drive engine 3 or the connection between the drive engine 3 and the differential 4 is stopped and blocked in such a manner that the two cable drums 5 and 6 are still connected via the differential 4. This produces the result that the two drums are free¬ ly rotatable but always in opposite directions so that any difference in the pull in the cables 8 and 9 is equalised so that the pull is always quite equal. This results in maximum opening of the trawl 2 and thereby maximum catch. Fig. 2 shows an example of a trawl winch with a me¬ chanical gear differential between the two drums. The drive engine 3 with drive gear (driving pinion) 14 is in mesh with the power input device 15 (crown wheel). The blocking means may for example be a mechanical blocking means 19 engaging the drive gear 14 or the power input device 15. It is also possible to perform the blocking by locking the drive engine 3. The cable drums 5 and 6 for the trawl cables 8 and 9 are arranged on a common shaft 12, 12' on either side of a gear differential 4 in that the drums 5 and 6 on the sides facing the differential are provided with a ring gear 17 operating as drum drives. Said drum drives 17 are in mesh with differential pinion gears 16 arranged on a retaining shaft 18 secured to the power input device 15 forming the crown wheel of the differential. The crown wheel 15 is a circular ring gear welded to the retaining shaft 18 and is designed with a circular ring gear with external teeth. The centre axis of the crown wheel 15 is common with that of the shaft 12 and the retaining shaft is at right angles to the main shaft 12. The main shaft 12, 12' is embedded in bearing pedes¬ tals 11 in the usual manner in that said bearing pedestals 11 are secured to the deck of the vessel. The two drums 5 and 6 are secured to the shaft 12 by solid bearings 13. The differential operates in the usual manner and for clearness the differential lock is not shown. The differential lock may moreover be designed in a generally known manner and such that it may either be manually operated or operated from the wheel house.

Claims: PATENT CLAIMS 1. Trawl winch for fishing vessel (1) comprising two cable drums (5,6) for each its trawl cable (8,9), said drums being operated by a drive engine (3), and means for controlling the cable drums in such a man¬ ner that when trawling the pulling action in both cables is substantially equal, characterised in that the two cable drums (5,6) are coupled to a common differential (4) having a differential lock and where the power input device (15) of the differential being coupled to the drive engine (3) may be blocked. 2. Trawl winch according to claim 1, characterised in that it further comprises a blocking means (19) for blocking the power input device (15) to the differen¬ tial (4). 3. Trawl winch according to claim 1 or 2, character- ised in that the two drums (5,6) are arranged on a common shaft (12,12' ) and on either side of the dif¬ ferential (4). 4. Trawl winch according to any one of claims 1-3, characterised in that the differential (4) is a me¬ chanical gear differential with a crown wheel (15) as power input device, differential pinion gears (16) arranged on a retaining shaft (18) on the crown wheel and ring gears operating as drum drives (17) secured to each its drum (5,6). 5. Trawl- winch according to any one of claims 1-4, characterised in that the power input device (15) of the differential is a circular ring gear with exter- nal teeth and with an axis common with the shaft (12,12' ) and secured to the retaining shaft (18) of the differential pinion gears (16) in that the re¬ taining shaft (18) is always at right angles to the shaft (12,12* ).

Inventors: BECH JOERGIN, BECH, JOERGIN
Applicants: BECH JOERGIN, BECH, JOERGIN
Application year: 1987
Main classification: A01K73
IPC codes: A01K73, B66D1