Can you mount a Fishfinder transducer inside a hull?

[Rivers & creeks]

We've got an Eagle Cuda 168 fishfinder but don't want to mount the transducer on the hull as it will create turbulence and I don't want anymore holes in the bottom! The manual says it can be mounted in hull but no matter where I try it, I can't get a good signal, it comes up with random figures, all way over the depth. I tested the unit with the transducer over the side and it was spot on. The hull is sold GRP and is a very very sharp V angle with a flat section on the inside of the V (HT27 Cat). Any suggestions? What should I try connecting it with ( I tried rubber sealant but that was a complete no-go). I also tried putting some water in the bilge and immersing it in that to test it, still random figures.

Thanks for any suggestions

 

[lydiamight]

Try using a large "blob" of bluetack between the transducer and the inside of the hull. Try a number of different places, if there are any voids in the fibreglass containing air bubbles you will get an incorrect reading. When you have found a place where you get a good reading use you blue tack to make up a small dam around the transducer and then fill with slow curing araldite--important that you do not use the quick setting version--place the transducer in the pool od araldite and wait until it sets. Job done.

 

[oldharry]

Also works fine in bilge water as long as the transducer face is parallel to the hull.

 

[Relax]

Done this several times on different boats.

Cut a length of ABS drain pipe slightly bigger diameter than the transducer so its vertical taking the hull deadrise into account and silicon seal this to the inside of the hull in a suitable place - i.e not near the keel, bilgeplates etc.

Put a little vegetable oil in the bottom - 3 or 4 cms. Put the transducer in this - it should work - mine does!

 

[Rivers & creeks]

Nice idea about the drainpipe - all the best places to use the other helpful suggestions are above the (shallow) keel - would it work through 18 inches of keel? Maybe that explains the false readings???

 

[Bodach na mara]

Lots of posts about this previously, but the search syatem makes finding them difficult. A variant of the above ideas is to use KY jelly or similar to find a good spot on the hull (I used walpaper paste actually) then clean and dry off the area before sticking the sensor down. If you do not like the permanance of epoxy (I didn't) then you can use silicon sealant (which I did.) Just use it without the screw-on nozzle to make sure there are no air bubbles.

 

[Relax]

I would doubt it would work through the keel but the turbulence there would give you false readings anyway I would suspect.

Mine is mounted just forward of the keel on the centre line.

I assume if its a through hull type its the short black cylinder on a threaded plastic neck (100mm long?) with the cable out the top? A 50mm pipe should fit.

 

[Relax]

I'm alway's a bit chary about doing this where the hull is'nt horizontal and the transducer ends up pointing off at an angle.

The 'beam' (?) of pings I understands varies in width depending on the frequency ( I think there are two different ones in use) so it may work but I would always have thought it better to have it vertical.

 

[ShipsWoofy]

I have mine mounted to the nacelle, it works pretty well. It is meant to be a transom mount, but I have suspended it under the water on two longish m6 bolts. I know you have the 27, but I don't think that your water clearance is much greater than ours. Advantage, obvious, no holes under waterline, water thermometer still works (handy).

Pic below.

 

[Rivers & creeks]

Thanks DW - how did you get access to that part of the nacelle?

 

[ShipsWoofy]

It is where, before the engines were fitted, the outboard well was. Now I have a lifting hatch which is where the whale gusher pump is located. There are a couple of holes to allow water out from pumping etc.

As you have an outboard (I seem to remember), I don't see why you could not mount the txducer in front of the engine leg?

The hole that our txducer is in front of on ours is just big enough to get fingers through, this is useful as the only downside of this location is that it occasionally picks up floating debris. It also allows me to wipe barnacles off. Though, this is not a massive problem, and cleaning it once a season is sufficient, i.e. you could mount it without immediate access if you needed to.

You could also mount it much further aft before the nacelle starts to rise, this would give access by dinghy. You could put the wire through a deck gland above the water line at a high point of the bridge deck, it only needs to be splash proof at that point, in fact, you could double up, put a gland inside and out.

 

[cid]

I installed a humingbird in the last few weeks. I used vaseling between the hull and the transducer and it works fine. Give it a go.

 

[Rivers & creeks]

Thanks DW - didn't twig where you meant at first. Yes I have the o/b version so it's readily accesible from there. Thanks for the suggestion cid but how do I explain the huge pot of vaseline to the the chemist?
me: "no really, I need it for my transducer..."
chemist: "is that what you call it?"