Transducer Fitting

Andy Gee · 26 April 2004, 19:14

I need some help/advice, I have got to fit a new transducer, through hull, however there is an old one from an Echopilot already fitted. I have removed the Echopilot (its crap) and would really quite like to fit the new transducer in the same place, there has been wood cut and laminated in to ensure that it sits level, however the old hole is 60mm and the new one is to be 51mm

Any Ideas other than putting in a new hole? would Sikaflex do the trick?? or any other ideas

If possible I would like to be able to refit fairley quickly as I am getting a lift out and hold overnight as I need the boat to be available 24/7 and cant have it out any longer..............it's never simple.
Andy

Andy · 26 April 2004, 19:29

Whatever you use make sure you minimise the air bubbles between the solid hull and the transducer. That means a layer of your resin or eppoxy first then sit the transducer on it. It must not be a dry interface. Bubbles will cause noise on the screen. I think other may be best at suggesting what substance you use so I will leave that to them.

marknj · 26 April 2004, 19:35

Hi, Yes Sikaflex should do the trick. Also worth considering pluging the hole and mounting the transducer inside the hull, this way it will not get damaged and the front face will not cause turbulance and thus poor performance at higher speeds. To fit it inside the hull you can silicone it straight to the hull but be carefull not to get any air traped and do not use Sikaflex for this as you will never move it again if you need to. Or bond the end cap of a soil waste pipe to the hull and fill with 50/50 water anti-freeze mix and suspend the TDCR in it, min half inch from hull as air can get traped between the two surfaces.
Good luck,
Mark

Dirk Diggler · 26 April 2004, 20:47

Both marknj & Andy obviously misread your post, assuming your transducer is through hull and doesn't just shoot through the hull.

A through hull transducer needs to be sealed with a "sikaflex" type adhesive/sealent, silicone should only be used above the waterline.

You need to either cut a new hole, or as the old hole needs to be filled, you could do this and then re-cut a smaller hole in the same place.

Out of interest, a "shoot" through the hull transducer should be installed with epoxy!

If you wanted to suspend the transducer in liquid, do as marknj suggests, but I would reccommend filling it with as light mineral oil.

Pete7 · 26 April 2004, 20:52

Agree with Dirk (for once) the water pressure under a hull at speed is somehting like 80 lbs sq inch! You are going to either fill that in and cut a new hole or perhaps have an engineering firm make a collett out of stainless steel to fill the hole in and take the new sounder.

Do a search for Portchester engineering they have some nice lathes which could do that.

Pete

marknj · 26 April 2004, 21:06

Just to clarify my last post.

Yes never use silicone for any type of skin fitting. But you can use use it to bond a transducer to the inside of a hull in the same way as epoxy. Have done this many times with no problem but still prefur the water & anti-freeze route. Oil used to be used but now all installations we do use water and anti-freeze, again with no problems and much cleaner when I spill it! I have used this method on all types of sounder/transducer from small £90 Garmins to £3-£4K Furuno units.

Mark.

Dirk Diggler · 26 April 2004, 21:08

Quote:

Originally Posted by Pete7

Agree with Dirk (for once) Pete

Daniel · 26 April 2004, 21:24

OK call me stupid, but what stops this water/antifreeze from sloshing straight out of the "soil waste pipe end" the very first time you use the RIB???

I'm missing something i know...

marknj · 26 April 2004, 21:30

Hi,
the soil pipe end cap comes with a seal.

Another tip is to put a little grease on the seal and a 3mm hole in the cap to let the air out when you put it on then put a ss self tapper in the hole

Mark

Mark Halliday · 27 April 2004, 08:01

Quote:

Originally Posted by marknj

Hi,
the soil pipe end cap comes with a seal.

Another tip is to put a little grease on the seal and a 3mm hole in the cap to let the air out when you put it on then put a ss self tapper in the hole

Mark

I have just done this with the tranducer for a Raymarine ST40. I used an 82mm Access plug (Osma part no. 3S.292 - £10.24) cut down and epoxied to inside of hull and filled with Castor oil. Worked fine to 36 kts at the week-end.
Leave the old transducer in to plug the hole. This way you do not have to lift the boat out of the water which will save you a days down time.

Andy Gee · 27 April 2004, 08:22

Thanks Guys,
I did think about the collet way, we have a machine shop at work, however I would much prefer to use the Osma way (I have loads of Osma fitting available), however would that way still work with a transducer that is supposed to be fitted "outside the hull", i.e would it be able to see through the hull layup?

Thanks again
Andy

MeMe · 27 April 2004, 09:17

Before you go..........

have a look at a thread I started in August last year. Do a search for "Transducer Mounting" and you'll find some additional tips along with mu conclussions. In brief, the way I did it works really well and I know others have followed suit and agree.

MeMe

Mark Halliday · 27 April 2004, 14:27

Quote:

Originally Posted by Andy Gee

Thanks Guys,
I did think about the collet way, we have a machine shop at work, however I would much prefer to use the Osma way (I have loads of Osma fitting available), however would that way still work with a transducer that is supposed to be fitted "outside the hull", i.e would it be able to see through the hull layup?

Thanks again
Andy

Raymarine use Airmar transducers, and I believe that many others use the same. You will loose some performance at the high (deep) readings because the hull will adsorb some of the energy, so it may only read to 600ft and not 900ft. If the bottom is that far away, who cares? I am only bothered when I am about to hit it with the prop. I can do you a sketch of my OSMA setup if you want, PM or email me if you would.

Andy Gee · 28 April 2004, 07:33

e-mail sent

Dirk Diggler · 28 April 2004, 08:27

I don't know the construction of a Red Bay, but if it has any sort of coring (balsa/foam etc) it will need to be cut out if your going the Osma route!

Mark Halliday · 28 April 2004, 09:17

Quote:

Originally Posted by Dirk Diggler

I don't know the construction of a Red Bay, but if it has any sort of coring (balsa/foam etc) it will need to be cut out if your going the Osma route!

Good point Dirk

However, if you go the thro' hull route you have to sleeve the core & inner skin, so why not use the Osma pipe to do that, an still save a hole in the outer skin?

Andy Gee · 03 May 2004, 09:23

Quote:

Originally Posted by Dirk Diggler

I don't know the construction of a Red Bay, but if it has any sort of coring (balsa/foam etc) it will need to be cut out if your going the Osma route!

Well I tried the thro hull way all over the boat and the maximum depth was always 6-7m even in 60m + water

and when I hung the trasducer over the side it gave the correct depth.
So I have had a collet turned to suit and am planning to get her lifted out this week. I don't think that the Redbays have a cored hull just a bloody thick one.
Andy