Trawl Design

Substantiation and Optimisation
of Trawl Design Parameters

The Programme is meant for calculations in the process of design of rope-net section of pelagic and bottom trawls. The Programme accounts for peculiarities of species behaviour, trawler traction force and general fishing conditions. Design procedure is based on parameters of a prototype gear and ground dynamic parameters.

Application

The Programme is used at pre-design and design stages of construction. It provides the following procedures:

substantiation of the main parameters of a new trawl on the basis of behaviour and distribution of targeted species and conditions of operation;
investigation of possibilities of adjusting already existing trawls for the new conditions of operation;
choice of the most suitable prototype (from the existing Data Base); alterations to a trawl design (procedure of adding or removing net plates, alteration of their dimensions, trying different mesh-size of nets);
calculation of main design parameters on the basis of corresponding parameters of a prototype trawl; precision of calculations is determined by structural and geometrical similarity of a designed trawl and its prototype;
obtaining a number of versions of a designed trawl configuration and choice of the optimum model on the basis of the criterion of the effectively trawled volume of water or catchibility coefficient;
calculation of geometrical and physical parameters of the trawler-otter boards-trawl system for identification of the necessary spreading force of a trawl board at specified speed of trawling.

Functions

The programme supports an open Data Base of the existing trawls (used as prototypes) and trawl designs, as well as traction values of different trawlers. It provides graphic interface for work with drawings of trawl tailoring. It provides the following calculations:

identification of the parameters of a designed trawl mouth, providing specified probability of overlapping of its area with the area of a fish shoal lateral cross-section;
calculation of combinations of main trawl parameters (size, speed, resistance, weighted mean diameter of twines and ropes) on the basis of trawler traction;
calculation of trawl parameters, providing equal catchibility of a prototype and a new trawl;
calculation of main parameters (speed, loading of footrope, moving horizon) of a deep-water trawl;
choice of models, satisfying requirements determined by peculiarities fish behaviour and optimum in relation to other requirements;
calculation and visualisation of the interconnection of the system vessel-warp-otter boards-cable-trawl.

Interfaces

The programme is run in Windows 3.1 environment and has a friendly interface, meant for engineers. Dialogues for entering data are supplied with the schemes, explaining the essence of required values. The results of calculations are shown on drawings.

Image 1: Entering structural and geometrical parameters of a prototype trawl.

Image 2: Calculation of main trawl parameters, provided by trawler's traction.

Image 3: Calculation of acting forces and position of otter boards and trawl in a specified mode of operation.

Upload the demo version of the program

CAD/CAM Laboratory, Commercial Fisheries Dpt.
of Kaliningrad State Technical University for Fisheries.
Russia, 236000 Kaliningrad , Sovietsky procpect 1,

Phone +7(0112)463818. BBS/Fax +7(0112)465487,
FIDONet 2:478/3 Fishwar BBS.
E-mail: sokolov@fishwar.koenig.su

Konstantin Sokolov

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