Relationship between canvas area and performance of the canvas spreader stow nets

The increase of canvas area not only promotes the net mouth opening, but also increases the overall resistance of the net. In order to understand the relationship between canvas area and net performance, 7 groups for model test were designed, the ratio of canvas area/net resistance (K) was used as an indicator for net performance. The 7 groups were divided into two parts according to research objective, (1) 5 groups within 7 groups were chosen to study the effect of the canvas areas on net performance, which the canvas areas increased gradually, but the canvas width/length ratio was similar; (2) 4 groups within 7 groups were chosen to estimate the effect of the canvas width/length ratio on the research result of part (1). The results show that: when the current speed was 0.24 m/s, the K rose with the canvas area increasing, but the rise rate slowed down gradually, as the canvas area was close to 0.288 m², the K was close to the peak; when the current speed was more than 0.4 m/s, the K was a constant, and the correlation between k and canvas area was not obvious. So when the canvas area was close to 0.288 m², the matching coefficient (P) of canvas area and net size was close to 0.072, the stow net can keep good performance under different current conditions. The effect of aspect ratio of canvas on K trend was not obvious. The power function relation was found between net resistance with canvas area and current speed, and the empirical formula was expressed as F=334.32×A^0.5×V ^1.61. As a common sense, the matching coefficient (P) and net resistance were affected by multiple factors, not only by canvas area and current speed. So the results were suitable for using in similar condition. If the conditions were different obviously, the coefficient and formula should be modified. The above findings can be used for the performance improvement of canvas spreader stow nets.