Mechanical Properties of a Rectangular Purse Seine in a Normal Operation

Abstract

The mechanical properties with factors of forces (tension; F and drag; D), velocity (v) and distance (s), in a normal operation were studied. Normal operation means pulling both ends of the purse line by a winch during the pursing stage and the hauling stage. The mechanical pro-perties at the equilibrium condition of the force were expressed in the pursing stage (suffix “1”) as; η₁=e^-πμ1, F₁=(F_wcosθ₁)/2, D₁=πη₁F_wcosθ₁, v₁=(V_wcosθ₁)/(πη₁) and s₁={(V_wcosθ₁)/(πη₁)}t, where θ₁=sin^-1 (W/F_w), and in the hauling stage (suffix “2”) (vertical pulling) as; v₂=1.0, F₂=F_w/2, D₂=F_w-W, v₂=V_w and s₂=V_w(t-t₁). Where η₁ and η₂ are the mechanical ef-ficiencies between the purse line and the ring, μ₁ is the kinetic friction coefficient between the purse line and the ring, F_w is the tension of the winch, W is the weight in water of the fishing gear, V_w is the velocity of the winch, and t₁ and t₂ are the time lapses during a fishing operation. If the factors μ₁, F_w, W, V_w, t₁ and t₂ are given as known constants, each factor of the mechanical pro-perties can be calculated.