Transom Mount Transducer mounted inside the hull in a bed of 'jelly'

[Twilite]

very cool idea..

[CarinaPDX]

Topic has been recently discussed, but some new info here so worth asking again.

I test mount using KY Jelly or similar; if it works well then it is easy to clean up and mount with silicone and if not easy to try again. I built up a flat and almost-level pad of resin in order to aim the transducer to the side of the keel. Even removing the puck with KY can be difficult once it dries due to the close fit; I had to use a chisel with silicone - I really like the dental floss idea. If you don't want to deal with making a resin pad then I would give the molten wax a try, but only after testing with KY first (removing the wax is going to be difficult).

The transducer pucks have come with epoxy in the past - don't do it!! You will have to destroy the puck in order to (re)move it.

Greg

[Cheechako]

I have sanded smooth and epoxied the transducer inside the hull. Worked fine. Although it's epoxy, not like you cant get it off with a blow of the hammer. Assuming when you want to take it off it's toast!

[Striker37]

I have my lowrance elite 5 DSI transducer on the bottom of my bilge in my all aluminum striker not glued just sitting there with 2 soft dive weights on top of it an it works great.My bilge is dry all the time so i just fill it with 3 inches of fresh water.

[Eleuthera 2014]

I've been interested... as I could not devise the solution.

Thank you all for the tips

[Ted and Relinda]

I mounted ours in a wet box made of a 4" PVC end with a screw cap filled with mineral oil, epoxied to hull just forward of the keel. Small slice in sidewall just enough too push wire through and sealed it with silicon. Has worked for 10 yrs with no problem. You mentioned you wanted to put it next to another through hull?? Watch for interference with each other if frequency is close...
Ted..

[dannyjoh]

My boat (26 feet fiber glass sailboat built in 1977) came with a brand new Hawkeye D10 in-hull depth sounder kit still in the package. I followed the instruction looking for a suitable spot all over the boat (including the bilge). No luck. The system works great when when I drop the transducer overboard. So there is nothing wrong with the functionality of the unit. This particular brand appears to be not strong enough for shooting and receiving signal through the hull of my boat. I am giving up on this one. Would someone recommend another brand/product I might try? Something a little more powerful?

Danny
s/v Feral, Marieholm 26

[Cheechako]

Originally Posted by dannyjoh

My boat (26 feet fiber glass sailboat built in 1977) came with a brand new Hawkeye D10 in-hull depth sounder kit still in the package. I followed the instruction looking for a suitable spot all over the boat (including the bilge). No luck. The system works great when when I drop the transducer overboard. So there is nothing wrong with the functionality of the unit. This particular brand appears to be not strong enough for shooting and receiving signal through the hull of my boat. I am giving up on this one. Would someone recommend another brand/product I might try? Something a little more powerful?

Danny
s/v Feral, Marieholm 26

I don't know that unit. Probably if you get one that is advertised as reading to deep depths would help. I've done it with fairly cheap fish finder types. The ones that scroll the bottom shape. They are advertised for fishing but some are very reasonable priced and read to 600 feet or more! And they have a digital depth readout as well as the bottom contour function.
Is it possible your boat has a cored hull?

[dannyjoh]

Cheechako,
Thank you for the feedback. As far as I understand, the Marieholm 26 doesn't have any core material in the hull or deck. It is supposed to be solid GRP. A marina neighbor suggested a Garmin in-hull transducer. I will look into it. Thanks again.

[Islandnut]

Originally Posted by David M

Any sort of material which can efficiently transmit sound will work. Generally speaking, the harder the material, the less will be the attenuation of sound. A hard bedding compound will transmit sound better than silicon sealant. The downside will be that if you ever need to remove the transducer that it might be more difficult with a harder bedding compound.

To give you guys a tad bit more info just in case you decide to try another compound....or multiple compounds that are harder directly underneath the transducer with wax surrounding it...

Water travels at 189 m/s
Steel travels at 57 m/s
Dolomite travels at down to ~30 m/s

All this is at 100% solid bond with no micro annulus(air pockets or gaps) which would cause a false reading. The most important thing is to stay away from attenuation of the signal.

Dow Corning makes some of the best silicone, but it's pricey !!

[captain58sailin]

Since it seems that a more rigid bedding compound would work better than a softer one, how about using "Splash zone" for the bedding? it is water proof and hardens well and you can break it if you need to remove or replace the transducer? Just a thought, I am in the process of putting in a new depth finder and was thinking about mounting the transducer without putting a new hole in the boat.

[sanibel sailor]

It is not hardness (water is pretty soft), but incompressibility is what is important for sound transmission.

[captain58sailin]

Have you ever done a belly flop in a pool? Felt pretty hard to me.

[Island Time O25]

I did that on my first boat. I was given an older but never used Eagle (Lowrance) fishfinder with a transom transducer. Googled the procedure and installed it with epoxy over the solid (not cored) f/g portion of the bottom. Worked like a charm even though the f/g at that point was almost 2" thick. The key to good installation is the lack of air bubbles in the epoxy, or whatever you may end up using as a bedding compound.

[elskede]

thank you all for input and advice!
stephen
xanadu
westsail 32 sailing south soon for ensanada...