A unique website dedicated to fishing information from Florida's Northern Big Bend. This includes the area from the Econfina River west to the Apalachicola River
Transducer looks way too low to me. Raise it till it's even with the bottom of the boat...and try it.
Mine breaks lock at high speeds too...most of the time. It seems to be normal for transducers located outside the boat.
I've never seen one mounted below the hull on a planing hull. Only seen it like that on a boat with a displacement configuration. Raise it up to be even with the bottom of the boat. However, anytime the transducer is mounted on the back of a planing hull where the water is boiling, you are going to have problems at high speeds. Best solution is to shot through the hull in the middle of the planing pad.
I agree with the "to low" comments already made One other possibility that I can't determine for sure from the pictures is.... how close to the lower unit is it when the motor is down? If it's too close that can be a problem from a turbulence issue
"Good Judgement" comes from experience, ... and a lot of that..... results from "Bad Judgement".
Looks low. While you are moving it check the lead wire and make sure it's are not frayed or shows excessive wear. Once removed, examine the transducer for any cracks or scratches. Air bubbles can get up in the scratches and give you false readings at speeds above an idle. Moving it up might not solve the problem, but will certainly get it out of harms way.
My .02
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