Tips on installing thru hull transducer?

[River Rat]

Just ordered a Furuno Fish Finder & a thru hull transducer. Ordered a fairing block as well. I'm installing it this weekend... any tips???

There is a old thru hull transducer that will be removed to install the new one.

Figured I would use 4200 to seal up the hole in the hull.

[Gerry Zagorski]

Jimmy - 4200 should be good to seal up the hole in the hull and it might be the best place to mount the new ducer. The reason I say this is 2 fold:

1) If your old ducer was working fine and reading the bottom while at speed then it's in a good area of the hull. You don't want any cavication bubbles under the particular area of the hull when you are under way because your machine will loose the bottom.

2) It is not reccomended to use shoot through hull ducers with anything but a solid fiberglass hull. There are a lot of boats out there that have cored hulls and the shoot through ducers don't like that.

So, if you fill in that old ducer hole with a solid material, chances are the ducer will work there.

[River Rat]

Yep, I plan on removing the old transducer and using that hole for the new one.

[mboy]

Look to see if airmar makes a tilted element for your FF. Then you won't need a fairing block.

Younggull and I (mostly Younggull) installed mine last year in about an hour or so.
Pretty straight forward.


Make sure the hole is even (may have to file down so the ducer sits flush in the hole.

Then run the cable thru and do a dry run of the install.

Once you are happy with the way it is sitting, slap some 4200 on the lip, mount it and tighten the nut hand tight.

Next day go back with a BIG ass wrench and tighten the nut all the way.

That's it.

If you go fairing block, I imagine it is a lot more work and a lot is involved.


The tilted element is pretty flush with hull, so none needed and mine works GREAT!

Toughest part was drilling a 3" hole in bottom of boat, but beyond that, it was fairly easy.

This is prob what you need:

http://airmartechnology.com/airmar20...runo&PageNo=67

[Gerry Zagorski]

Never mind..... I see you are using a through hull ducer and not a shoot through hull ducer.

[CaptBob]

If your present Tranducer location is working fine, use that hole.

Clean area inside and out before mounting

Use 5200 to seal

Put on the High Speed Plastic Faring Block (use one with my Furuno and get good reads to 22 knts)

Make sure you get the angle on the Faring block correct before cutting, Measure Twice-Cut once

[Capt. Debbie]

The biggest problem with transducres is where to install them.

Air is your mortal enemy. So location is really the MOST important factor of all. Why transducers stop working at higher speeds is air between the transducer face and the water.

I assume you were happy with the old location and the performance it gave you? If it started to lose the bottom at a certain speed, this one likely be very close if not the same speed where it can't see the bottom too.

If you're not happy with the speed it lost the bottom at, consider a new location. Away from the chines that bring in air to lift the hull. And as deep in the bottom in areas that stay in the water as possible. Like near the keel forward of the transom.

Admittedly if you relocate it's more work as you still have the old hole to fill. Or just disconnect it electrically and physically abandon theold transducer in place to avoid having to fill that old hole.

My two cents. )

Capt. Frank