Surface mounting a through-the-hull tranducer?

[ChasB]

Anyone had any experience of mounting a through-the-hull transducer on the inside of a grp hull? Does it work? Anyone tried and failed?

I'm kind of loathe to drill any holes in the hull - particularly since I've no plans to take the boat out the water again till next year! /forums/images/graemlins/blush.gif

/forums/images/graemlins/ooo.gif

 

[guernseyman]

Yes, just follow the instructions, particularly regarding cleanliness: your bilges are likely to be oily/greasy, so make sure there's naught left so you have an oil-tight seal for the transducer.

 

[roly_voya]

You can test it by setting up a plastercine dam, fill it with water and put the transducer in the water then check the readout on the instrument head. Will probably just reduce the max depth reading. You can then move it around to get the best location

 

[BrendanS]

A slightly easier way is to put the transducer into a small plastic bag, fill the bag with water and tape it off so the water can't escape, then get an helper to put the bag/transducer in various locations on the hull whilst underway. Rig up the display temprorarily near the helm. You can then see the results from the different positions. Better to test underway than whilst stationary, as bubbles, water flow, etc can affect results.

Most tranducers will work fine through grp.

 

[VicS]

[ QUOTE ]
Anyone had any experience of mounting a through-the-hull transducer on the inside of a grp hull? Does it work

[/ QUOTE ]

My transducer is designed to be mounted through the hull in wooden boats etc but inside a grp hull.

It is mounted in a plastic tube containing castor oil glassed to the inside. I may have bought a mounting kit or I may have used plastic plumbing bits, I forget which. I works perfectly well and is situated on the centre line fairly well forward.

Almost any liquid which wont freeze or attack transducer, grp or mounting tube can be used.

 

[gjgm]

some say use silicon, others epoxy/araldite- but dont use the fast set as it can hold bubbles in the mixture. Also normal epoxy is pretty runny, so you might need a litle plastercine bath ring around the transducer to stop all the epoxy running out.
But if you can glue to bits of paper together, you can do this!

 

[Norman_E]

I experimented last year by sticking the transducer down "temporarily" with Blue Tack. It works down to about 20 metres, which is all I need for a back up second depth sounder, and so far I have not changed it.

 

[samwise]

I installed our Navman depth sounder as surface mount and it works fine. The problem we had with our Westerly was that the original transducer was pretty much glassed in to the hull and I didn't fancy making yet another hole in the boat. I used a length of plastic pipe that made a good fit with the unit and Plastic Padding to fix it to the hull. You can fabricate a cap from the standard pipe end cap. As previous posters have said, the fixing surface should be grease free and should be roughed up a bit to provide a good key for the adhesive.

I have seen several recommendations for filling the tube, castor oil, olive oil etc. What works for us is that KY jelly stuff they use in hospitals for foetal scan machines. It does a brilliant job and does not slop about or risk a spillage into the bilge. You can get it in the chemist where it is sold for "other"purposes.

 

[geoffatstanpit]

I stuck mine on with Bluetack 7 years ago and it still works fine on an Incastec whirly red light type which I prefer - it tells you how sure it is and what the bottom's like! I had readings all the way to Cherbourg (twice and a bit round the dial in the middle!)

 

[PeterGibbs]

A medium is required that carries the signals to and from the transducer without disortion. The trick is to avoid any bubbles of air between the transducer and the sea, so using a liquid, castor oil is excellent, that is stable, does not evaporate and is easy to top up is strongly recommended.

However, the part of the hull you choose to mount this gear on could contain bubbles in the structure in which case you will not only loose some depth readout, you will encounter irregularities in performance. Be prepared to move the site a little if it doesn't work first time as you expect, then glass in or use a proprietary putty.

A piece of domestic plastic piping sawn to produce a vertical fit on the hull will do just fine. Then just drop the transducer into the oil.

All the above worked for me.

PWG

 

[ChasB]

Cheers everyone! Very helpful.

Sometimes I tell people who need technical advice on something that they should find a relevant forum because they are an excellent source of advice, with their own checks for inaccuracies (other forum users!) and often I get a "I'm not a computer geek like you" response. So foolish, and I'm a little disappointed in them. Forums like this one have completely changed the way I source a lot of information. How else would I have got the wealth of practical info above in only a few hours?

Thanks again.

 

[simonfraser]

stick it down with silicone