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Transducer


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Hi all

I have decided to try and fit my fishfinder myself. I was just wondering if anyone had a in-hull transducer i could have a quick look at (near Brundall) so i can get a rough look at how it should look when its properly fitted. It looks simple enough and im going to swap the wires over from the old one to the new so should be ok there and the rest is plug and play but i want to get the transducer bit right.

Im going over Thursday lunchtime to spend a few hours seeing how to get the cable from the dash to the bay, Im quite looking forward to the challenge but dont want to put the transducer in the wrong position and mess up the readings it produces.

Andy.

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I assume it is a "shoot through hull" type where it is stuck to the inside of the hull otherwise stop reading now.

Do it temporarily with some ordinary bath silicone Andy then test and see if it gives consistent readings. About a quarter to a third of the boat length from the transom and about a sixth of the beam out from the keel, on the port side is a good place to start. When you are satisfied then clean it all up and epoxy it in permenantly.

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Thats right, it is stuck to the inside of the hull. there is one stuck to the port side already but its old and not compatible with anything out there today. It does look tho that it has just been plonked into a whole tube of something (looks like a pattie) and just sits in the middle.

I will do the same as that if thats right? The old one is a oil filled thing, I dont think i need to encase the new one tho? just place the new one into the silicone? or cover the new one completely?

Once im happy with the readings just fully coat everything in epoxy?

Thanks.

Andy.

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Has it got to be the port side? The old one is there at the moment, If i can get it up ill put the new one in the same place but i was thinking the starboard side would be ok?? and leave the old one where it was.

Lastly :) What sort of epoxy? I just googled it and there is no end of different stuff from glue to concrete to msds whatever that is

thanks again.

Andy.

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It matters not which side you locate it Andy, just as long as its as close to the keel (the deepest part of the hull) as practical, and not to near the stern, where the water will be turbulent.

As far as expoxy goes, then as long as its compatible with GRP (its very unlikely not to be), it will be fine.

You'll not need a lot, and a small pack of Plastic Padding Marine Epoxy will do the job nicely.

Don't forget the cut the bottom of the tube to the same angle as the hull, so that it is plumb vertical when installed, and don't overfill it with castor oil, or it will spill over when you insert the transducer ;) . Do make sure though, that the transducer is fully immersed in the castot oil, as it relies on there not being any air space between it and the hull.

Dave

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The port side is just a good place to start Andy, it's where most factory fitted ones go, but either side can be effective, it should NOT be close to the keel or any spray rails as turbulence at speed will affect it, though it’s fine for a slow boat. The difference can be set in the “keel offset†menu on your fishfinder so it shows depth under the drives. The important thing is not to commit yourself by epoxying it permanently until you have tested it at all speeds and the silicone will do that job nicely until you are satisfied all is well and then you can epoxy it down. Make sure you give the hull a good clean and a wipe down with acetone to make sure the epoxy can stick well, don’t get acetone on the surface of the transducer. Some current transducers allow you to fit directly to even a deep V hull and then set the deadrise angle on a dial so that's worth checking in the manual as it makes the job a lot simpler.

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Huge thanks for the information. Much appreciated. Has definately answered a lot of questions i had. I'm now fairly confident to give it a go. I also saw i could place it in a sandwich bag filled with water to test it too which might be easier,

I got the Garmin in-hull transducer which is about 2" wide so im thinking i just need to fix it to the hull and thats it? Or do i need to make a small gully for it and cover it with oil as Dave said?

This is it. and that is how it came in a box so no tube to cut or anything..

http://www.handtec.co.uk/product.php/13 ... 5618bdbc85

Sorry to keep asking so many questions.. :oops:

many thanks

Andy

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What you have there is type of transducer I alluded to in my last post Andy, it can be epoxied straight onto the hull making sure there are no bubbles in the mix of epoxy and that you don’t use too much between the transducer and hull. You can then dial up the deadrise on the top of it to compensate for the angle, take care that you read the instructions thoroughly as it will almost certainly have an arrow which MUST point toward the bow. I like the idea of a plastic bag of water for initial testing when stationary as you can easily move it about. I still recommend that you fix it with silicone temporarily for “sea trial†purposes though.

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Oooh!!, that's different Andy, and I've not seen one like that before :?

The old Seafarer, and now the current NASA units, have an in-hull mounting kit, comprising a length of plastic tube, a bottle of castor oil, a sealing cap, and a pack of Plastic Padding epoxy, to affix the tube to the hull.

David has obviously come across the Garmin type before. :)

Dave

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David has obviously come across the Garmin type before. :) Dave

They are all similar and made largely by Airmar Dave, Garmin, Raymarine et al don't make transducers so the Garmin one shown is the same as many other manufacturers offerings. The old seafarer mushroom is a good reliable unit but really old technology now. In fact NASA still appeared to using the same one as they were when I visited their factory to write a piece on them in the mid eighties right up until they stopped making them not that long ago.

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Thanks guys.

Will probably take her up and down bradon a few times with the silicone but i did read it should be enclosed for the best readings which is why im wondering if im supposed to completely encase the transducer with epoxy when i go for the final bond? or is the only bit i need covered is the bit i epoxy to the hull?

Will get you both a pint when i see you (or 2) cheers ..

Andy cheersbar

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Hi Andy ,talking to the man from Garmin at the Birmingham show at the weekend and he said to do as you say put in in a water filled bag and move it around the bottom of the boat to find the best position.He said the oil filled tube should give a good result without the risks with epoxy which once set is virtually for good.Good practice or not it could be worth a try.and you can still fix by other methods if it does not work. cheersbar

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The water filled bag is great for stationary initial checking Roy, but is no help when you need to test the thing under use as it is not possible to keep it still, the thing must be tested underway at all speeds as even though you may get a good signal when stationary, turbulence when underway must be checked as the signal can easily be lost. Also the type of transducer Andy has is specifically designed (unlike the mushroom type) to be epoxied to the hull. Hence the advice to try it using silicone until its effectiveness is proven.

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Massive thanks to you all. i'm now bursting to get to the boat and start dismantling the old one and getting the new one set up. Much appreciated guys. Owe you all a pint or 2 :) Will let you know how i get on over the next few days :)

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