(No Through Hull) Transducer

[ButchL]

Is there a transducer available that is not through hull mounted for wood hulls. My hull is 7/8 inch thick cedar, full keel. I haven't been able to find one searching the web. If not, other than the "lead line", is there another way for determining water depth.

Butch

[kc8pql]

There are no depth transducers that will work mounted inside a wood hull. Uncored fiberglass yes, but not wood. There are transom mounted transducers often used on smaller outboards that may or may not work on your boat, depending on what it is. If you decide to go ahead and use a thruhull be sure it's bronze and not plastic. Plastic isn't recomended for wood hulls.

[Bob Adams]

There are no depth transducers that will work mounted inside a wood hull. Uncored fiberglass yes, but not wood. There are transom mounted transducers often used on smaller outboards that may or may not work on your boat, depending on what it is. If you decide to go ahead and use a thruhull be sure it's bronze and not plastic. Plastic isn't recomended for wood hulls.

Not 100% true. If you have a wet bilge, and mount the transducer in the puddle, it will work. Not quite as accurate, and suffers from a reduction in range, but you can shoot thru a wood hull, Been there, done it.

[kc8pql]

I defer to your experience. I'd think that the degree of success would depend on how thick the hull is and maybe what kind of wood. The frequency of the transducer could effect it too, lower being better than high?

[Todd Bradshaw]

I once called Lowrance about shooting through a hull. Their suggestion for testing was to buy a jar of "Dipity-Do" hair gel. You put a goodly blob of it on the floor, set the transducer in it and see what happens. If it works with the gel, it can work with a more conventional method of securing it to the floor (like resin, I presume). If it doesn't work, you can still use the stuff to give your wife a really swell bee-hive.

[Tom Lathrop]

It depends on the thickness of the wood hull and whether the wood is dry or wet. 7/8" is a lot of wood to shoot through. Yes, the low frequency will work better but for shallow water you need the high frequency so there is the rub. All depth sounder makers brag about the max depth capability which most of us don't need but neglect to say what the minimum depth capability is. I recently called a couple of them to find this out but did not get definitive responses.

I cut a hole in the bottom of my boat, beveled the edges on both sides and filled with glass and epoxy. I made a wood block in the shape of the transducer, covered the bottom of the block with plastic tape and set it in epoxy on the inside. After removing the bock, the transducer was set in the formed recess in a thin pad of silicone.

Works as well as any transducer. The transom mount transducers that most manufacturers supply work fine this way so you don't have to pay extra for the through hull type.

[donald branscom]

Thru hull transducers have caused me a lot of trouble.
If i have another one it will be mounted on the transom on a flip down strut. That way i can see it and clean it .

The transducer usually works but the problem is the speed log paddle.
When i put my boat in the water it works and by the second or third day forget it. No matter what anti fouling i have tried nothing works.

[kc8pql]

the problem is the speed log paddle.
When i put my boat in the water it works and by the second or third day forget it. No matter what anti fouling i have tried nothing works.

My speed transducer can be pulled from the inside to clean the paddle. There's a sort of flapper valve in the housing that closes when you pull the innards out that mostly stops the water until you seal it up with a blank plug that came with the unit. Some water gets in but nothing you can't sponge up when you're done.

[Paul Fitzgerald]

I recently put a Navman in a glass hull, with an in-hull transducer. They said to put it in a zip lock bag in water, and move it around the hull to find the right spot.
I did and left it there for a few months, no problems. It is now fixed permanently in Sikaflex.
In the past I have also used a through hull transducer inside a glass hull, no problems.
Why not get your hands on an old sounder and transducer and try it out, there should be a wet bit of wood somewhere.

[Gary Bergman]

Our thru-hull's on Royaliste are outdated, and won't work with the new nav gear,so...we have traveled thousands of nm's on a stem mounted transducer and a cheap fish finder...looks like crap, works great...

[JimJ]

I have had success shooting through 9mm ply on Sea Lark.

I really don't care about the maximum depth. If the specifications for the depth instrument state 0-200 feet and I only get 0-100 feet shooting through a ply hull, who cares.

It is the minimum depth I am interested. Like the last 2-4 feet.
Jim

[ucb4ume]

You can test your transducer to see if it works before permanently installing it. I tested mine by placing it in a pool of water and holding it in pace with a weight of some sort (I used a bean bag filled with lead shot).

I have installed two different transducers inside my wooden boat without any problems. The bottom of the hull was made up of 1/4 inch marine fir plywood with 1/8 inch mahogany veneer and several coats epoxy.

I installed the transducers by placing them in a pool of unthickened epoxy directly on the inside bottom of the hull. Just make sure the transducer is level and that there are no bubbles in the epoxy.

I have had no problems getting depth readings at speeds as high as 35 mph. I don't know how deep it would work since all of my boating takes place in shallow water (less than 50ft).

[Nick C]

There are two solutions:
Mount a transom mount transducer
Cut a hole in your boat where the transducer goes then sand a dip in the bottom around it. Not lay up three or more layers of fiberglass cloth. Now pour resin in the hole and fill to top.

Mount tranducer on top of that. It will shoot thru the solid mass and work fine. I suggest you use some type of glue that you can remove. I used to use shoe goo in my kayak, then I could just pull it loose when I wanted to. You may want something more permanent, though.

[WX]

A good and relevant old thread right now. Thank you gentlemen for having discussed it.

[PeterSibley]

I thought I'd find you here Gary .

[WX]

I thought I'd find you here Gary .

Yeah, I should use the search function there's a lot of good info back here in the storeroom.

[Peter Malcolm Jardine]

In a small boat, I can understand a transom mount transducer. On a boat with a bilge, I don't know what the issue is. Depth sounder transducers need to point straight down, and mounting through the hull is easy, simple, and problemfree.

[WX]

In a small boat, I can understand a transom mount transducer. On a boat with a bilge, I don't know what the issue is. Depth sounder transducers need to point straight down, and mounting through the hull is easy, simple, and problemfree.

My transducer is plastic and mounting these through the hull is frowned upon. I can do it in such a way that apart from the cable it would be isolated from the bilge. Anyway I'll do a couple of the tests suggested here and then make up my mind on my course of action.

[Peter Malcolm Jardine]

I should have been more clear: I use only through hull transducers that are designed to be installed through the hull. My electronics didn't come with transducers, so I chose the through hull type.

[Garret]

My transducer is plastic and mounting these through the hull is frowned upon.

May I ask why? I have a 12 year old plastic transducer through 1.5" AYC with a 1" backing plate. No problems so far.

As far as paddles go - yeah - worthless, I use my GPS. Of course that's SOG, but most of the time that's what counts....

[landlocked sailor]

I did exactly as Tom Lathrop with a transducer meant to be transom mounted. It was a bit nerve racking to cut a hole in a perfectly good bottom but it works fine. Rick

[WX]

May I ask why? I have a 12 year old plastic transducer through 1.5" AYC with a 1" backing plate. No problems so far.

As far as paddles go - yeah - worthless, I use my GPS. Of course that's SOG, but most of the time that's what counts....

I'm just going by comments I have read on the matter.
Regarding paddles, if I am correct the problem is marine growth? Has anyone tried coating the paddle with Lanolin? I ask because mine is the paddle type.

[Garret]

I'm just going by comments I have read on the matter.
Regarding paddles, if I am correct the problem is marine growth? Has anyone tried coating the paddle with Lanolin? I ask because mine is the paddle type.

I haven't

[Breakaway]

Aboard my powerboat, I spray the paddle wheel with aerosol anti-fouling intended for sterndrives and outboards. It works pretty well. Of course I cruise at 23 knots and often run at 30 kts, so that there is a fair degree of "self cleaning" going on. Your mileage may vary.

Additionally, I usually go overboard with a mask and fins once a month, during the warmer seasons, and check the bottom, including the ducers. I make this task part of the day when we anchor to swim, fish, clam or wade in to the beach. If a growth is occurring, I clean it off ( which of course removes some antifouling paint, so its a double edged sword)

Kevin

[Dan McCosh]

The guy next to me has a transducer installed in an internal box, attached to the hull planking, filled with water. He says it works fine. Mine is mounted in a fairly large block screwed to the outside of the planking--a kind of fairing. It adds drag, but works fine, requiring only the wire to go through the planking.