Research On Operation Characteristic And Safety Of Purse Seiner

Fishery development is paid more attention by all fishing power nations. However, China on coastal and open sea resources in use are subjected to all aspects of constraints, one aspect is the lack of advanced fishing technologies and advanced fishing vessels.In recent years, large scale tuna purse-seine fishing vessels come out to the purse-seine fishery. Our country has begun designing and manufacturing large-scale tuna purse-seine fishing ships. But, many of existing domestic purse-seine fishing vessels are remade from other types vessels, with the quatity increasing, the related accidents often happen.To enhance the stability of fishing vessels is necessary.Firstly, the paper introduces the seiner. Characteristics of work and sailing are researched. By analysis of purse-seining operations, study the unsafe factors during the procedure.Secondly, on those basises, the paper detaitledly analyses the moment of hauling net, rolling impacts and moment of sliding fish catches.1.By analysis of the force during the hauling stage, by solving rolling differential equations,study the rolling of the vessel under hauling moment. Analyse the stress of the seiner during the hauling, consider the maximum heeling moment at the end of heaving away the hauling rope.2.Types of fish catches determine the angle when catches start sliding, the angleθ0 and breadth of fish hold determine capsizing moment. With an actual vessel, when all the holds'catches slide calculate under differentθ0,the residual stability of the vessel is deficiency whenθ0 is at 3°and 6°,the residual stability is always sufficient whenθ0 is at 10°.The result indicates that the smaller ofθ0 causes more unsafe of the vessel.3.Hauling the net under different winds, calculate the stability of the vessel hauling at upwind and downwind. Calculating the stability criterion of actual ship, the ship is in danger when the hauling side is at downwind; the ship is apt to safety when the hauling side is at downwind.Considerring the maximum rolling angle is 22.5°in rules, calculate the stability criterion of actual ship when haul the net slowly, the vessel conforms to the safety request of fishing vessels'operation. As a result, the vessel is apt to haul slowly at upwind. If necessary, the wok boat tows the seiner at the opposite the hauling side, which induces the affect of hauling moment.In view of the above calculations and researchs, in order to ensure seiners'safety, the paper puts forward measures on operating, fishing and loading areas. We should pay more attention to protect safety of the catches and the vessels.