Depth transducer

Ralph Johnstone · Apr 16, 2012

An easy test doesn't really come to mind, however, consider the following thought process:

if you re-launch and the transducer doesn't work, you would probably install a non-thruhull transducer. As far as the old, dead transducer goes, do you really want to remove the dead one when it makes an excellent plug for the old hole ?

Don12364 · Apr 17, 2012

Hunters bonded my transducer in with 5200 (grhh!) - so it meant virtually destroying the transducer to get it out when it died.

However if you already have yours out of the hull you can do a tube test.

Get a 6' length of drain pipe or sewer pipe (or longer). The 4" or 6" PVC stuff is ideal. Cap the end off. Both items cheaply available in local plumbing suppliers. I had a bit lying idle.
Stand it on end and fill with water.
Dangle the transducer in the top and you will see how long your pipe is - or not as the case may be!
I once tested a sounder by taping the transducer to a stick and offering it into the lock on the local canal. Measured depth, width and length. I'm such a geek.

Pretty boring stuff really and certainly not worth the trouble of disturbing a perfectly good in hull transducer for.

SamLust · Apr 17, 2012

With the transducer connected to the instrument, turn it on and put your ear up against the transducer. You should hear clicking. That, if nothing else will indicate it is sending out.

gpdno · Apr 17, 2012

rblevens said:
Are the non thru hull transducers accurate??? I don't have any experience with them. Thanks for all the great advice!

I have the hull mount hockey puck style Garmin transducer in my boat. Works well, no issues. It's at least as accurate as the steel tape I used for calibrating my keel offset.

Ralph Johnstone · Apr 19, 2012

rblevens said:
Are the non thru hull transducers accurate??? I don't have any experience with them. Thanks for all the great advice!

I really have to wonder if ANY depth transducer needs to be installed as a thru-hull.

A friend of mine had a non thru-hull transducer which he was about to install and wondered the same thing as to the accuracy. For an experiment, we filled a zip lock baggy with water, placed it on a flat, smooth section of the interior hull and placed the transducer on the baggy. With zero offset on the readout, the reading compared perfectly to the old weight on a string reading.

He finally installed it by squeezing out (with the nozzle almost touching the interior hull) a large puddle of bubble free silicone sealant. He then placed the transducer in the puddle and let it set. The big thing was to avoid bubbles as much as possible. Mind you, he's all thumbs so probably most anything will work.

I have an older thru-hull transducer and we always have the same reading (+/- a foot) when rafted up.

I'd be interested if an old thru-hull type sensor would work if installed in the same way.

SamLust · Apr 19, 2012

For a given brand the transducer "works", or innards, are all the same. The difference is in the housing in which it is mounted. That is, a through hull housing, or an in hull housing, or a transom mount housing.

DianaOfBurlington · Apr 22, 2012

Many thanks to Ralph and Sam and especially Donalex for creative and thoughtful solutions to this concern, which I have had too. I ripped out the old SR Mariner one before I was smart enough to find out if I could get a replacement (which I can) and then settled on a Hawkeye one with an in-hull transducer, which hopefully gets installed this season.

One thing I learned from working at West Marine is that pretty much all transducers run on the same frequency, be they Garmin, Raymarine, or whosever. I think it is either 55 or 52 mHz (I forget exactly; someone help here); but the point is that you can ask and if it's the right freq then it will work with your head unit. So all that remains is to find one of which you like the mounting style and hook it up.

SamLust · Apr 23, 2012

DianaOfBurlington said:
Many thanks to Ralph and Sam and especially Donalex for creative and thoughtful solutions to this concern, which I have had too. I ripped out the old SR Mariner one before I was smart enough to find out if I could get a replacement (which I can) and then settled on a Hawkeye one with an in-hull transducer, which hopefully gets installed this season.

Great timing, JC. I've had a box of SR Mariner depth and speed along with two depth transducers sitting on a cabinet for 12 years. Too lazy to make up an ad for them in the SBO classifieds. They were the original instruments on my Hunter 33 and doing me no good at all.