Aluminium hull transponder

seedog

seedog

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I have a 22ft Extravert aluminium hull trailer sailor. Could anyone advise me on fitting a depth/fish finder internally rather than through the Hull. I would like to avoid drilling a hole in the bottom of the boat unless absolutely necessary.

I have searched YBW forum posts and looked at the posts/replies. However they seem to all be about wood or glass. The hull thickness is 3mm (I think) and I propose setting the transponder in resin forward of the drop keel unless someone thinks I'm wrong. Anyone got any thoughts on best practice or possible problems. If so has anyone any thoughts or suggestions, would like to hear your experiences
 
I used to have one of those! For the unenlightened, here's what they look like...

extranef.jpg


I wanted the answer to exactly the same question when I got mine. The answer unfortunately is you will have to drill a hole. Depth sounders won't work through a metal hull. The difference in densities between metal and water is too great.

I tried anyway, and it didn't work, and ended up having a hole. It's not a big job to do, and you don't have any problem of water getting into the laminate.

My transducers were under the forward berths in front of the keel as close to the centre line as possible. A boatyard fitted depth and log transducers for me for £50, and I never had any problem.
 
If you really don't want to drill a hole, have you considered fitting a transom mounted transponder. Just a thought.
 
It might seem a bit like overkill, but Echopilot make a custom aluminium transducer housing for their FLS models. It's machined from solid billet, and is not cheap at around £300 (then the cost of the unit), but is an ideal solution for an aluminium hull.

Maybe someone else makes (or would machine up) something similar for a smaller unit?
 
Thanks Angus and to everyone else for their advice and comments. Boat is currently sat in Portishead boatyard awaiting launch next week. Will see if they can sort me out as all my tools are still in Yorkshire.
 
Is this a new boat for you? If it is hope all goes well with it. Expect lots of quizzical people to come and have a look at it and ask strange questions.

I owned mine for a few years and had a great time with it. Not all boat yards/chandlers are familiar with aly boats. If you want to know any more come back here. Main points to living with it successfully are...
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Use an appropriate antifoul paint that says it's suitable for aluminum.

Keep copper out of the bilges. Take care when wiring not to drop scraps and keep tabs on loose change. No mercury on board.

Get a couple of dangling anodes fitted, and throw them overboard when not moving.

Don't use the hull as an electrical return path like cars do.

If leaving the boat it water when not used, lift the keel far enough to get the top plate out of the water. This only takes a moment each time.

Never sail with the keel anything other than fully down and locked.
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