Study on sinking performance of falling-net based on different weights

We compared the sinking performance of falling-net of four different weights (1 515 kg, 1 615 kg, 1 715 kg and 1 815 kg) near the Spratly Islands in the South China Sea. The results show that: 1) according to multiple regression model, the maximum sinking depth (D) was positively correlated with weights (W), shooting duration (T_s), hauling duration (T_h) and wind speed (S_w), but negatively correlated with drift speed (S_d). 2) The partial correlation coefficients show that the relative materiality of weight was greater than shooting duration, and overlong shooting duration was bad for fast closing of net mouth, so it is suggested that increasing weights is a more effective method to increase the sinking depth than extending shooting duration. 3) With increasing weight, the average maximum sinking depths of net mouth were 77.5 m, 81.5 m, 83.7 m and 97.9 m, respectively; the average sinking speeds were 0.303 m · s^-1, 0.318 m · s^-1, 0.342 m · s^-1 and 0.349 m · s^-1, respectively, both increased with weight; and One-Way analysis of variance reveals that significant difference existed in the maximum sinking depth and sinking speed among four different weights. 4) It is concluded that 1 715 kg is the optimum weight.