TZT picking up downrigger ball as bottom

[sbirdrob]

I have been slow trolling Mackerel for Tuna recently and have been using a downrigger at 100ft. in very deep water where the unti cannot 'find bottom'.

My B275LHW picks up the downrigger ball, but it appears the processor determines that is the bottom and gives me poor returns below the downrigger ball.

I am currently running the gain high, TVG high and clutter low.

Can someone point me in the right direction to solve this?

 

[Magnetron]

Greetings Sbirdrob,

The B275LHW is a sensitive single beam, so it'll have a single beam limitation of hitting the top of something and calling it bottom especially if that echo return is very strong. Furuno sounders do not need to be ran with the gain so hot, you may want to try to half the gain and TVG making that downrigger ball not as pronounced a target and set a manual range triple the size of what you actually need putting it all in the sounder view.

That being said, a triple-or multibeam DFF3D sounder is different and maybe able to better differentiate downrigger ball from bottom given multiple inputs (e.g. beams).

The acoustics folks may have additional points to add,

Hope this helps, :sail

- Maggy