Design aspects and laboratory simulation study of a floating marine fish cage prototype with mooring system

Abstract

In India, open sea cage culture has been successfully demonstrated and several experimental offshore cages for mariculture were installed along the coast for on-farm demonstration by the Central Marine Fisheries Research Institute, Cochin. In the present study, a model cage was fabricated and tested in a towing tank under different waves and current load conditions. The tension on the mooring chain was measured during the experimental study, besides the towing speed and wave parameters. Based on the experimental data, drag coefficient for the cage net twine was estimated. The tensions in the mooring chain and the cage net twine of the prototype cage were predicted based on the model data. The maximum tension on a single twine of the outer and inner fish net were estimated as 0.15 N and 0.028 N respectively. The force on the net was more than 1.7 times the force on the floating collar and sinker pipe. The tension in the mooring line is mainly due to the force on the net. Further it was observed that the force on the net due to current was 10 times higher than that due to wave. This information will be useful in future while deciding the diameter of the cage, the type of net to be used for cage according to the site where the cage is to be installed.