sounder issues

[mr-canada]

Ok i have a pirhanna2 fishfinder sounder, shooting thru hull, been mounted for a while since well before I bought the boat

it was working aok when I bought the boat but this year has been acting up. I figured it was slime on the bottom (mostly freshwater at the docks) so I grabbed the brush and scrubbed down there where the transducer was and viola it worked and started reading 18ft.

A few days later it was reading spotty, still is. I looked up the hummingbird site for help and figured out that if I take it off of auto and set it to the right range it will better aquire a lock on the bottom, which is true. Still spotty though, there are times it jumps in 20 ft of water to 215ft, 150ft, 0ft, then back to 20ft, hairbrained to say the least when I have a 5 ft draught.

I scrubbed and scrubbed and scrubbed down there so much that I noticed I was starting to take paint off and stopped but the problem prevails. No serious issues with water where the transducer is mounted its almost always dry as a bone, maybe some moisture at best. The epoxy its mounted to the hull on has never been bothered since I got the boat, no accidental kicks or anything, its underneath the companionway stairs going down so nothing has whacked it. (hummingbird says this problem can result from bubbles in the epoxy sealing it to the hull).

Do transducers eventually just fail like this? I doubt it's the electronics in the display as they seem to work just fine (theres no electronics other than the tranducer and the display). There's already an old school transducer mounted down there plus the one that's hooked up, I dont want to end up with three widgets expoxied to the hull that I cant remove.

Maybe there's a way to fix it? I havent hauled out since I got the boat over a year ago but I've seen other guys at the YC go on the grid and other than a bit of slime the bottom of the boats were clean from a foot below the water so its not barnacles or anything serious.

Suggestions welcome. Im in a channel with some nutty dry parts and I dont want to run aground. Plus having an accurate sounding makes it easier to drop crab traps without guessing. Scrub some more?

[dugout]

Two things can be happening.
1. dead transducer. they usually fail all at once.
2. transducer has come lose and there is air between it and the hull.
either or both...

[Mike OReilly]

Transducers do fail. I had a 15+ year one go bad, and ended up replacing it. Started showing random errors. At first not bad; would show crazy numbers, then back to correct. Error time kept increasing. I finally put an oscilloscope on the data stream (thanks to a friend), and confirmed the output was jumping all over the place.

If you've ruled out all other possibilities, like electrical connections, air bubbles or growth, then perhaps it is time to replace. I don't know if they can be repaired -- like most things electronic, I bet it's hard to do.