DEVICE FOR AUTOMATIC RAISING OF FISH TRAPS CRAYFISH POTS NETS AND THE LIKE

摘要

1516989 Automatic raising of fish traps and the like C W CHALLENGER 10 June 1975 24809/75 Heading A1A A device for automatically raising fish traps, crayfish pots and nets comprising a gas container 35, Fig. 4, connected through a control valve 36 to a pair of rubber bladders 33 which, together with respective cylindrical metal holders 31 having perforations 32 at each end, act as bouyancy chambers. A tap 38 is opened, the bladders 33 deflated by pulling on the ends of lengths of rubber 34, Figs. 5 and 6 the tap 38 closed and, after baiting the trap is lowered. The control valve, activated by a radio or coded sound signal sent through the water, opens to admit gas to the bladders 33 which expels water from the holders 31 and out through holes 32 and the trap rises, while excess gas escapes through a pressure relief valve 37. An alternative embodiment is a trap, Fig. 2 formed from a buoyancy chamber itself, which is a coiled plastics pipe 11, 12, 13, connected near one end 17 via a pipe 21 and control valve 20 to a gas cylinder 19. The trap's mouth 14 is made of rigid plastics. The tap 18 at one end 17 of the pipe 11-13 is opened, the pipe is filled with water through the open end 16 and the tap 18 is closed. After baiting, the trap is lowered. A coded sound signal opens valve 20, and the gas expels water from the pipe 11-13 and the trap floats. The control valve 36 or 20 comprises a signal receiver, signal decoder and solenoid driver, which operates the valve. Means for ready location of trap, e.g. radio transmitter, balloon are described.