Hydrodynamic performance of kotabaru’s traditional bottom trawl under the flume tank experiment

Abstract EN

Hydrodynamic performance of a 1/8 scale model of traditional bottom trawl was investigated in a flume tank.

It was to represent prototype of a bottom trawl with a low engine power of 33 HP at a towing speed of 3-knot, which is commonly used in Kotabaru, Indonesia.

At a towing speed of 3-knot (96 cm s-1 in model scale), the net heights at different wing tips distances varied from 7.0 to 9.2 cm, the projective areas of net mouth from 6.35×102 to 8.44×102 cm2, water filtering volume from 32.04×103 to 40.55×103 m3 and total net resistance from 11.07×102 to 13.46×102 g.

In the present study, the values of H/a ratio obtained was low (0.029 to 0.038) because there was no square part on the net body construction.

The net height was 3.4 % of net circumference and getting lower at higher towing speeds.

Water flow velocity and pressure distribution around trawl can alternate mesh shape from diamond to parallelogram.

The average exponent value 1.37 was less than the suggested value (2.0); thus, the shape of net body under towing condition should be refined.