Furuno GP1971F Looses bottom over 12 knots

[blackfin]

I have a Furuno GP 1971F with a Airmar B175M Thru Hull Chip 20 degree Transducer in a 1980 Blackfin. When I go over 10 knots I loose all signals on the deep finder. I believe I should see the bottom and It's contents even if I go 25 Knots. Do I need a booster if there is any?

 

[Kraken]

As a general rule, if losing bottom image when underway it is often more about the transducer placement than it is the capabilities of the transducer. Cavitation (Air boundary layer) can cause air bubbles to get beneath the face of the transducer and can cause it to lose bottom. If the transducer is giving you a good image on your sounder while under 10 knots and you lose image and depth over 10 knots then this is most likely the problem.

 

[blackfin]

Thank you for your response. I was afraid of that. I have a Furuno NAVET RDP 139 with a transducer in a flaring block and the same issue. Besides moving present transducer is there a way to rectify this?

 

[Kraken]

Unfortunately not. If the transducer operates fine at slower speeds then it is an issue of mounting location.