MOUNTING SONAR TRANCEIVERS

[fishfingers]

For my sins I work with military sonar’s amongst other things. I have read the transceiver mount discussion with some interest and would like to suggest a very simple way to semi-permanent mount the transducer in your hull.

 

------ Buy a hot glue gun !-------

 

Use the general hot melt adhesive, that inevitably came with it, and stick the transducer to the hull. Sounds too simple to be true? Well I use this method to temporally mount sensors under test and its more than good enough for the sort of frequencies used in commercial fishfinders.

 

I would suggest that you first clean the hull with a drop of meths after roughing it with a little glass paper. Don’t rough the sensor just wipe with meths to remove any grease, or from the sounds of most installations, half a pint of Vaseline !!.

 

Work quickly, melt a large blob on the hull and mount the transducer on top. Just make sure that the whole bottom face is covered so you get a nice clean sound path. Hold for a minute or two to cool. I would suggest that you play with the glue gun first to get a feel for the setting time before you go for your first mount.

 

While your at it you can also tack the wires out of the way with the glue if you so fancy.

 

The slight elasticity of the glue will work a lot better than any epoxy with the inevitable flexing and thermal movement of the plastic hull, also the joint will not melt in the sun like Vaseline leaving you covered and the butt of the inevitable crude jokes.

 

To remove, just heat a knife and slide it between the hull and the transceiver, though with a screwdriver, and a little care, you should be able to pry it off.

 

Just make sure the adhesive is not the wood type as this stuff soaks up water, it won’t damage anything but your sensor coming loose while on the water would be a pain.

 

I would imagine that you could then find a plastic container of some sort and hot glue this over the transceiver if you want more mechanical protection, but the hold should be pretty strong. Not pooh to a baby’s blanket, but strong none the less.

 

As an aside, hot melt glue is fabulous stuff for boating/fishing in general. It will seal small deck fittings with a lot less hassle, mess, expense and time over RTV silicone.

You can carry a stick in your kit and with the aid of a lighter, solve all kinds of problems, not least sticking rod tips back on. The later has happened to me twice in while fishing, once in the middle of Africa on the only rod I had with me, having a glue stick in my kit made me a ‘smug git’ ,as my companion pointed out.

 

Hope this is of use.

[Karl K]

If my boat ever arrives i'll get to try this. I did think about the hot melt glue and I apologise in advance if this is a numpty question but isn't there a chance that the "hot" glue could damage the Yak? Or does it not get hot enough?

cheers

karl

[fishfingers]

Karl, there is no way you can put enough energy quickly into the hull of your kayak to melt it with a hot glue gun. If you have ever seen any plastic welding it will take a lot to reach the glass transition temperature ( a fancy way of saying melting) of the plastic, and its thermal conduction is so poor that only local melting occurs or else you wouldn’t be able to weld it. In other words heat over a few seconds will not effect the kayak, just don’t use a blow torch.

[darnsarf]

Hey Fishfingers great tip. Just so happens my transducer is in need of as bit of attention so will give it a go.

[finn17]

Good tip. Thanks!

[Starvinmarvin]

This is quite interesting as I tested many Epoxies, Silicon Sealant Adhesives and glues before I mounted my first transducer in the Caper Project, hot glue was amongst them. I still stand by the Devcon 2 Ton Epoxy which is still stuck fast inside the Caper. Mind you haven't had a problem with the Vaseline method either.

 

But I have another project that I'm working on at the moment and I may well give the glue gun method another look.

 

How long has your transducer been stuck in place? I'm interested because as you are probably aware the main problem with Polyethylene and most if not all plastics is that they leach an oil from their surface, this is probably the main cause of all these transducers popping off here an there.

 

SM

 

Hey Darnsarf,

 

Told you that old Araldite wasn't up to it

 

SM

[fishfingers]

Marvin, as you rightly pointed out this method is not permanent. The hot melt adhesive does not chemically fuse to the components, it kind of acts like millions of tiny bungs in the pores of the plastics which holds the two together. I would imagine that over a period of a couple of months the bond my well come off. You just stick it back down again.

 

Interestingly if you have a large area to cover and no glue gun, just heat some sticks in an old tin can on a low oven. Trowel it on, and mount your transducer.

(Jamie Oliver eat your heart out !)

 

If you note in the topic starter I recommended that you did not sand paper the transceiver. In doing this the glue puck should just peel off totally cleanly, a bit like the glue they use to stick freebies to the front of fishing mag’s.

 

Because of the low adhesion properties of the rotomolded plastics, I recommended that you roughed the surface of the hull. This in effect will increase the mechanical ‘bung’ grip on this component. It should however still peel away totally cleanly if needs be.

 

If the glue puck is still fairly clean you can reheat it in the oven again and reuse.

 

Try this simple experiment at home first before you try it on your fishfinder.

Use the melted glue to stick the plastic bottle top off a plastic milk bottle to the side of the same milk bottle. Now peel the bottle top off. This will give you a feel for the bond that will be achieved in your kayak.

 

Hope this clarifies, us engineers can be a bit woolly sometimes.

 

Regards, Fishfingers

[darnsarf]

SM fair point but in fairness I did drop the yak right on the transducer spot over a deck chair arm. Might also have contributed.

 

SM fair point but in fairness I did drop the yak right on the transducer spot over a deck chair arm. Might also have contributed.

 

Does anybody else hear an echo!

 

Also want to investigate using a water bath in the hull. Any ideas welcome.

Edited July 26, 2006 by darnsarf

[Starvinmarvin]

That is the other area that I'm investigating for the Malibu II XL Project, Nifty has used this method and I believe Speciman has too. Nifty has used a soap dish which appears to work quite well.

 

Easiest thing for us to all do is buy a Prowler Elite 4.5 then there would be no fixing issues... oh unless you don't have a Humminbird transducer

 

SM

[fishfingers]

It would initially seem like a good idea to have your Transceiver exposed in an Elile 4.5 style, but if you dropped your kayak on a chair leg you would be looking for a new transceiver instead of fixing the old one back on.

 

I don’t think the transducer will hold up to an emergency 'seal' landing on rocks. But then I suppose if things get to this, you won't care about your fishfinder.

 

I like the potential of the Elite 4.5, but from a technical perspective the recessed under mount transceiver will cause drag, just how much is in question, but when your supplying the motive force you could seriously effect the top end speed of the kayak negating a bit/lot of the benefits of going to a long hull shape?

 

Time will tell on this one.