Depth finder not getting depth.

[JordanL]

I got a new fiberglass boat last year. The transducer for the lowrance is shoot thru hull. At cruising speed it will not register depth. Just wondering if my only option is to put one on the back. I took it to the dealer a couple of times and they were no help. Thanks, Jordan

[PerchJerker]

You might have a bad bond to the bottom of your boat. One trick to test the transducer is to have enough water in your bilge to make sure your transducer is submerged, then try it and see what happens. If it works that means the mounting is bad, if you can pop it out and remount it you should be good to go.

Another possibility is if the transducer is mounted too far forward, that part of the hull might not be in good contact with the water at cruising speed??

[sparkyaber]

Don't for get the software issues, I had a shoot through the hull, and it worked fine in deeper water, but not in shallow water.

This sounds like a different situation, so I would do what perch posted first.

Does it matter what depth, what unit? where is it mounted? Does it work when you are not underway?

[JordanL]

Yea it works fine when going really slow or still. Its a lowrance 510. I think its mounted in a good spot, Really close to the back. The dealer said that they remounted it but i am not to sure of that. I am going out this weekend and will take a little better look at it. I really dont want to have to mount a new one on the back but if thats what it takes then i guess i will. Thanks for the input.

[PerchJerker]

You should be able to shoot through the hull, tons of guys do it. Try the water in the bilge test to see what that does for you. Good luck with it.

[Ed Carlson]

What hull style do you have? Do you have a modified tunnel hull with an inset below your sump where the ducer is installed? If so...that might be an issue...as at high speed it will produce cavitation in that area and cause the in-hull to malfunction due to air bubble turbulence below the ducer. If this is the case you may need to do a transom mount to get ideal hi-speed performance no matter what.

What type of ducer did they use to shoot through the hull to start with? Did they use a Hi-Speed and epoxy it in (a Bad plan as they can easily get off center in installation), or did they use a ducer designed for the install?

The installation may have been poor, or the original ducer may be bad from the get-go...or as was previously stated, it may be a Lowrance software issue.

Do the wet test with a puck ducer submerged in the sump with a bag of sang holding it in place firmly.... and then see if the unit reads properly at all speeds. Try several positions in the sump to see if it reads better in a different location, and note it when and if it does.

You may be able to re-set the original ducer and see if the epoxy or placement was the culprit in the original installation reading poorly?

If you re-epoxy a new ducer in..DO NOT TURN the unit on for at least 12 hours after installation, as this can cause the epoxy to develop pockets that will diminish the acoustic conductivity and ruin the installation.