To simplify calculations, fishing net was assumed to be composed of lumped mass point which
interconnected the massless cylinders (Fig. 3). We concentrated lumped point masses on each knot and on
the center of mesh bar for knot netting, and knot was assumed to be spherical point where the fluid force
coefficient was constant (Fig. 3(a)). For knotless netting, a mesh bar was divided into two parts at the
center, and two parts of the connected bars constitute a cylinder. The mass was lumped at the center (Fig.
3(b))