ROPE AND NET CALCULATIONS APPLIED TO PROBLEMS IN MARINE ENGINEERING AND FISHERIES RESEARCH

The mathematical-physical simulation of the performance of heavy rope and net systems has proved a powerful tool for the engineer. It has be en used effectively in the development of fishing gear. This paper pre sents results on the application of a special method for calculating t he shape of flexible twine tension systems and the loads acting on the m. Since the formation of the required equation system is rather time- consuming and because each model needs to be programmed separately, th is method has so far only been used by specialists. Now, however, resu lts can be obtained after a very short time, owing to automatic format ion of equations and the application of universal calculation and obse rvation routines. After a short period of training this method can als o be used by non-specialists. Reticulate systems consisting of up to 2 (15) elements can be calculated within a period of a few hours. The ex pert gets more time to deal with the external loads acting on the syst ems and with the corresponding hydrodynamic problems occurring. These questions are still not solved in most cases. Hopefully, future result s will increase our understanding of the functioning of selective and non-selective fishing gear. The examples shown for trawls and for the calculation of trap net segments demonstrate the great importance of t his method in the use of new materials for fishing gear which can not be observed directly or satisfactorily In most cases it is not possibl e to obtain adequate results in an empirical and experimental way or e lse it would be extremely expensive.