An uprated version of Furuno’s F3D-S 3D sonar is now available. The version has several new functions particularly adapted to trawl fishing and integrates with both with Imagenex trawl sonars and Marport Scala2 sensors.
According to Furuno Norge, with both Imagenex and Marport connected, the result is an excellent overview of the trawl depth, opening and the doors, providing better control of the gear. The new version has a bottom gain function and corresponding user adjustment options, which eliminates the problem of bottom echoes in shallower waters such as in the North Sea.
The Furuno F3D-S 3D sonar has always had a bottom filter function enabling a preset bottom line with a user-defined distance to the bottom. This function filters out echoes from the bottom in the 2D and 3D view, but in the vertical section it was still a problem to distinguish between fish and bottom.
The new bottom gain function adjusts the gain below a certain depth and filters out the echoes from the presentation, as well as in the vertical section. The adjustment is automatic and based on analyses of recordings with bottom echoes for various sea areas. Based on the results of the analyses, the relevant user programmes for North Sea herring, Atlanto-Scandian herring, North Sea mackerel and capelin have been adjusted.
The F3D-S presents information from the Imagenex trawl sonar and from Marport Scala2 both as text in a data window and as symbols in the graphic presentation. The sonar provides depth data and the height of the trawl opening measured as the distance between the trawl sonar and the fishing line. This is presented as HDPT (headline depth) and HF (headline to fishing line) in the data window.
Echoes from the propeller water can mask echoes from the doors, and this can be avoided by setting the upper red line, one of two manually adjustable depth lines for echo filtering, under propeller noise. This makes echoes from the trawl doors easily visible in the 2D and 3D view.
Echoes from fish can also obscure the trawl doors. With Marport Scala2 connected, F3D-S presents depth of trawl doors and wire length automatically, both in the data window and in the graphical presentations.
