How to mount depth transducer on steel hull

[Orchidius]

Hey guys,

A while back I installed the depthmeter on our steel-hulled boat. I didn't bother with the transducer at the time since it wasn't to be used for another little while. I'm looking into it atm, but most info I can find is targeted at GRP boats. Using car bodyfiller to mount the transducer to the hull and then glass it in.

How would one go about this on a steel-hulled boat? It's the kind that doesn't need a hole drilled in the hull.

Thanks!

[Cheechako]

Will a transducer shoot thru steel? I don't think so...?

[a64pilot]

I don't think one will shoot thru the hull either, I'd look into transom mounting or similar if you don't want to or can't cut a hole in the boat.
Of course call the manufacturer of your device to be sure

[RaymondR]

Internal installation of the transducer will not work on a steel boat; the density of steel is many times that of fibreglass and the steel absorbs all the signal energy.

[Mishiwa]

My transducer is mounted through hull aprox 1/3 of hull length from bow and 1m below water line (I draw 1.8m) with a wedge shaped fibreglass block facing forwards. Works well.

[Island Time O25]

Originally Posted by a64pilot

I don't think one will shoot thru the hull either, I'd look into transom mounting or similar if you don't want to or can't cut a hole in the boat.
Of course call the manufacturer of your device to be sure

If the hull is solid f/b and not a sandwich it'll work fine. Just needs to be epoxied without any bubbles and fully below the waterline of course. On my previous boat I installed it like that and it worked flawlessly.

Would also be interested to find out how it is installed on a steel hull.

[GordMay]

Airmar says:
“Can I install an in-hull transducer in a steel or wood hull?
No, the signal from an in-hull transducer cannot penetrate dense steel, and will not transmit through wood because it has too many air spaces.”
➥ Airmar FAQ - C...

[a64pilot]

Originally Posted by Island Time O25

If the hull is solid f/b and not a sandwich it'll work fine. Just needs to be epoxied without any bubbles and fully below the waterline of course. On my previous boat I installed it like that and it worked flawlessly.

Would also be interested to find out how it is installed on a steel hull.

Yeah I know, last boat I siliconed the mount , filled it with car antifreeze and it worked great, you don't need epoxy, but this guy has a steel hull

[NSboatman]

You can do this relatively easily on Steel - but it does involve cutting and welding. Can't avoid that I'm afraid - unless you go transom mount.

If you can cut and weld (or get it done), then:

Get a suitable diameter piece of steel pipe (probably ~4" dia or so for most round 1.5" dia transducer heads - you need to leave room for the nut flange on the inside and weld on the outside). Depending on the curvature of the hull you might only need 4" of it, or you might need 10"... Pick compatible steel to your hull steel... you need to know what this is first. Make sure your welder knows what it is so that the right welding procedures and consumables can be used.

Weld (properly - this is going to be your hull skin now) a cap on one end, and drill the 1.5" hole for the transducer, then test fit it. The cap thickness should be the same or more than your hull plate thickness. 1/4" min.

Offer the pipe up to the hull where you want the penetration to be, holding the pipe vertical to the axis of the boat (parallel to the line of your mast). A plumb bob helps here. blocking the boat level is a good idea too!

Scribe/transfer the round shape of the pipe OD up onto the hull (it will be a weird distorted ellipse due to hull curvature). This is the hole you need to cut in the hull plate. Once it's cut, cleaned up and ready for welds (grind back paint and coatings form the edges both inside and out), slide the pipe up inside the hole and align vertically again. hold in place with magnets or blocking while you level/line it up.

Scribe the shape of the hull on the pipe inside - leave 1/2" or so sticking up past the plate. Remove the pipe, cut it to shape on this scribed line, then re-insert and align. Alternately you can leave it long and trim it with a zip disk later too. Presuming you can access it well.

Fillet weld inside and out, inspect for weld integrity (no holes, no cold spots, no cracks, no undercuts etc etc), blast/brush/clean, and then paint. If you want to get really fancy, fill rough surface of the welds with a nice thick epoxy fillet paste before painting and blend it with hand sanding to make it look super smooth. THEN paint.

Then fit your transducer in it's newly minted housing, sika/3m the crap out of it and you're good to go.

see.... easy!

bg

[doocruiser]

Originally Posted by a64pilot

Yeah I know, last boat I siliconed the mount , filled it with car antifreeze and it worked great, you don't need epoxy, but this guy has a steel hull

hello can you give me some advice please. i have a lowrance depth/fish finder which has a skimmer transducer for mounting on the rear of a speed boat. its shaped like a partially flattened egg. i have a wooden hull which i have cut a hole in, then inserted a 5 mm glass plate and then glassed the under side to the hull so it will be shooting straight through glass only. lowrance support say expoxy it in only for it to work. i want to avoid this, i may want to take it out in the future. i have heard people submerge them in olive oil as well.your installation sounds ideal.can you explain it better for me please. i was thinking of splonking it down with 3m 5200 or sica. do you have a small box around it with a lid or something similar to hold the antifreeze in ?
reguards
scottie