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Old 13-06-2011, 16:20   #1
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Depth Sounder in a Steel Boat

I have recently completed a steel hull sailboat. The transducer for the depth sounder (a Stnandard Horizon DS41) is partially recessed to protect it from logs etc. The sounder only works intermittantly. It works fine when tested out of the boat. I bought a new transducer but no help. I'm wondering if someone, preferrably someone who has a recessed transducer, can recommend a depth sounder that works???

More detail: The recess is made from a piece of pipe with a slightly larger dia than the xducer, cut at an angle and welded to the bottom. One edge of the xducer is almost flush with the bottom plating and the opposite edge is recessed approx 1 ". The recess doesn't seem to trap air.

I have tried painting the recess with sound deadening paint. No help. Actually, it doesn't work at all now.

I have jury rigged another sounder and sailed from North East MD to the Rio Dulce, but would like to have a more permanent solution.

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Old 13-06-2011, 20:11   #2
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Re: Depth Sounder in a steel boat

Have you considered a transom-mounted sounder?
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Old 13-06-2011, 20:22   #3
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Re: Depth Sounder in a steel boat

Test the transducer in a bucket of water? Or over the side of the boat?

Your recessed port may cavitate. The vapor bubble will greatly attenuate the signal. But of course this will only happen at speed. Might have been better to recess it just slightly below the hull surface...or flush. Most units have such a wide beam that the angle of the hull is not an issue with performance.
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Old 13-06-2011, 21:02   #4
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Re: Depth Sounder in a steel boat

Transducers like a clean laminar flow across them. Try fabricating a spacer so the head is more into the clean flow of water. It won't be perfect as far as protection from the logs go, but at least it will work.
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Old 14-06-2011, 14:02   #5
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Re: Depth Sounder in a steel boat

Thanks for the suggestions!

I hadn't considered non-laminar flow to be the problem because the sounder doesn't work standing still either. I was thinking more that the steel was receiving blips and transferring them to the transducer where it touches the hull and thus confusing its brain. I was hopeing that someone would say that xyz hs a better brain and doesn't get confused. I may try to contact some manufacturers.

All else failing, I'll probably take DavidM's suggestion and extend the transducer (assuming it's long enough) until it is clear of the hull and fill in the recess with epoxy.

I'm currently using a transducer that's mounted in cockpit drain. (I have 2" cockpit drains). I tried mountin a xducer off the stern but it had to be rather deep to stay in the water when the boat was pitching.
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Old 14-06-2011, 14:11   #6
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Re: Depth Sounder in a steel boat

Can you fill the void with resin?
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Old 14-06-2011, 14:25   #7
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Re: Depth Sounder in a steel boat

i sailed a steelie for 10 mo with depth sounder of unknown make -- worked great-- gooodluck--i know there is a way to fix your problem....smooooth sailing.
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Old 14-06-2011, 18:21   #8
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Re: Depth Sounder in a steel boat

Boracay has a Raymarine ST40 Bidata.

I had a piece of steel bar machined up to accurately fit the depth transducer, so that it sits horizontal and just proud of the hull. Paid a professional welder to weld it in. It works perfectly.

My paddle wheel log on the other hand...

My guess is that the "sound" is reflecting back from the lip into the transducer. I'd go along with the suggestion to make up a large washer to "push" the transducer further down and clear of any nearby steel.
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Old 15-06-2011, 07:33   #9
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Re: Depth Sounder in a Steel Boat

I have two sounders (apelco, ST50) both work perfectly well with a steel hull, they are mounted before the fin keel as per manufacturers recommendations, they protrude so little that I doubt that they can be easily damaged. To test them out of the water I use a piece of 100mm dia plastic pipe that I fit between the ground and the transducer, I use wedges to press the pipe against the hull. The pipe is capped at the bottom and full of water. Both sounders give me the exact length of the pipe water column.
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Old 15-06-2011, 07:54   #10
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Re: Depth Sounder in a steel boat

Quote:
Originally Posted by James S View Post
Can you fill the void with resin?
Since the void points down, I will need to add some thickener to the epoxy. Any suggestions on what to use? It will need to have the same sound tranmissibility as water. Milled fiberglass fibers? One edge of the xducer will havevery little epoxy to shoot thru; the other edge will have1.5-2". Will this cause problems?
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Old 15-06-2011, 12:23   #11
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Re: Depth Sounder in a Steel Boat

My understanding is that the difference in thickness wouldn't matter.
As far as the material itself is concerned, epoxy or polyester resin with glass fibers in the laminet is OK as long as there is no voids or air bubbles...ANYWHERE bettwen the transducer and the final finished surface.
I imagine there could be some fillers that could be added to the mix but my Fiberglass technical expertise is a bit dated so not sure what they would be.
We do have several members with a much better understanding of these materials.
Hopefully some one will confirm/clarify what I believe is the case.
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