Fishfinder transducers through hull mounting

[jonjonc]

Does ne one know how to mount a humminbird 250dx transducer on the inside of a fibreglass hull i keep ripping my transducer bracket off, could someone direct me to a msg board that could tell us?

[Geoff R]

I know they do a lot of through hull transducers, it may be best to look at the site, check out your model and click on the accessories for it. Failing that ring up Rhyss Whittred at Access or someone from Millards and ask them, if your in the Golden State of course.
Regards Geoff

need to be sure your glass hull isn't a cored hull (i.e end grain balsa sandwiched between inner and outer layers of glass.

Some older boats were cored below waterline for strength / cheapness (to save on glass), and transducers don' like shooting thru wood.

Assuming it's solid glass, then the transducer should shoot thru it OK.

There two ways to mount the transducer to the glass.

1. Permanent = epoxy it to the hull
2. Removable = in an oil bath.

Do you think you want a permanent install or are you likely to later want to shif the sounder and transducer to another boat?

Lemme know and I'll detail how to do either method.

Cheers!

[jonjonc]

Yeah the transducer is not going to be moved out of the boat its in at the moment, the hull is the same hull as a haines signature and i rang the people at haines and they said i could do through hull but couldn't tell me how to do it.

cheers Jono (btw i am in the best state of them all being WA, golden if you will)

Permanent method is to epoxy the transducer to the inside of the glass hull.

You need to be very sure - that where you place it, will have "clean" (not aerated) water directly beneath it.

This means, not directly on top of the keel, or on top of planing strakes, and not so far forward that part of the hull is out of the water while on plane.

Best spot seems to be on the planing pad toward the rear 1/3rd of the hull - off to one side of the keel, and with no thru hulls etc directly in front of it to feed a stream of bubbles under the transducer.

Where it's to be installed needs to be clean, free of oil and old fuel etc...if necessary put some acetone on a rag and gove it a good clean first, but wash it cean, and let it dry before trying to set the expoxy.

When you mix up the expoxy - get 24 hr cure, MARINE epoxy (this usually has a 72 hour breakdown halflife in water) as bilges tend to get wet from time to time.

Mix sufficient epoxy to "seat" the transducer into so it has a good even bed. Mix the epoxy VERY slowly so as NOT to introduce any bubbles into the mix..you don't want bubbles in the epoxy trapped between the transducer / glass / water. Stirring the epoxy fast willl aerate it which is what you want to avoid.

Make sure before you start you have enough transducer cable to reach your display screen, from the installaton point you've chosen.

The temp method of installation is to get a short length of PVC 8 inch dia pipe, and cut it onb an angle so it sits up against the bottom of the hull inside and comes up straight (perpendicular) to just below floor height.

Glue it to hull with sikaflex,

Fill the little "well" with enough mineral oil so it is deep enough to cover your transducer, and pop the transduicer into the oil.

It will now read bottom thru the oil / glass / water /

If you want to - you can 'thread the transducer cable" thru a hole drilled in a circle of flat PVC which is the same dia of the pipe and cap the oil bath bye glueing it on, to stop oil spilling into your bilge whenyou come off waves etc..

Either way will work - you can later remove the oil and sikaflexed PVC pipe if shifting the transducer to a new boat whereas once the transducer's epoxied in place it's part of the hull for good.

You may find with both methods you need to boost the gain setting a bit to compensate for the glass / expoxy or oil expoxy that the transducer will now be shooting thru, which it wasn't having to shoot thru when transom mounted.

Cheers & good luck

[Flynut]

I once had a Freedom hull that kept on breaking and had to get my money back on....well most of it :( - long story. Anyway I had my Humminbird transducer epoxied to the hull and it worked fine. The only thing I might add to Trouty's method though, which I was told was important, is to make sure the transducer is installed level ie not just epoxied directly to the hull where the deadrise angle will shoot your sonar out to one side. Use a short piece of pvc pipe cut at one end to the angle of your hull so the other end sits level. Glue 2 paddle pop sticks to the top of the t'ducer to support it when it's placed in the mould. Pour epoxy slowly from one side only and you shouldn't get any bubbles.
The only downside to the epoxy method,as Trouty said, was that now I only have the screen as it was impossible to remove the transducer from the hull when the boat went.:(
good luck
Dave

[jonjonc]

All you guy's info is very useful and i am about do it but last question is how do i get to the bottom most part of the hull or do i have to cut a hole?

Cheers Jonjon