Best method for filling hole from thru hull?

[CarlF]

I just finished pulling all the old lowrance equipment off of my bass boat, and Im left with a hole in the hull where the old flush mount transducer use to be. I know that I could just fiberglass the hole and permanently fill it, but I'm wondering if anyone has come up with another way to do it? A plug of some sort would be nice, in case I ever sell the boat or decide to get the flush mount Humminbird transducer.

Any ideas?

[fishnkamp]

I doubt a plug could stand up to the pressure while running. I would have it fiberglassed or have left the transducer in place.l

[CarlF]

I pulled the transducer. Selling the whole setup to a fishing buddy.

[S Hovanec]

another vote for leaving it in place.  Drop the price of the unit so he can buy a new transducer.

[Fishing Rhino]

How thick is the hull at the site of the transducer?

 

Here's a simple solution that can easily be undone to install a transducer.

 

Get one of these through hull fittings.  They are available in several sizes.  To install it, put a 1/4" bead of silicone on the flange.  Then snug the fitting against the hull until the silicone starts to ooze around the edges, and let it sit for a day or so until it is thoroughly set.  Use a finger to remove, and smooth the excess silicone.

 

Then, once set, you can tighten it down without the silicone oozing out.  Once installed, you can cap the threaded end.  Those are not pipe threads, but for what you are doing, it will work.  Get the appropriate size cap, wrap the threads with Teflon tape, and screw the cap on tightly.  Put the boat in the water, and check for leaks.

 

It will be a clean, simple, install, and uninstall.

[CarlF]

15 minutes ago, Fishing Rhino said:

How thick is the hull at the site of the transducer?

Ill have to measure when I get home, but if I remember correctly, its a circular hole with a 2" diameter. The fiberglass is about an inch thick. Again this is a rough approximation.

[WRB]

You could have a machine shop make you a dummy TD from aluminum or brass using 2 -16UN OD thread, washer and jam nut, about 1 1/2" long. I did this decades ago and it works. I used a O-ring design but 3M 5200 sealant would work and easier to make the plug.

Tom

[Angry John]

You should be able to replicate the transducer face out of polycarbonate and just use some 100% silicone.  I would go with some material about 1/4 thick or even 3/8ths.  The materail works well with wood tools like a router.  

[Deleted account]

On 1/11/2018 at 11:00 AM, fishnkamp said:

I doubt a plug could stand up to the pressure while running. I would have it fiberglassed or have left the transducer in place.l

This^.

[CarlF]

 

 

Get one of these through hull fittings.  They are available in several sizes.  To install it, put a 1/4" bead of silicone on the flange.  Then snug the fitting against the hull until the silicone starts to ooze around the edges, and let it sit for a day or so until it is thoroughly set.  Use a finger to remove, and smooth the excess silicone.

 

Then, once set, you can tighten it down without the silicone oozing out.  Once installed, you can cap the threaded end.  Those are not pipe threads, but for what you are doing, it will work.  Get the appropriate size cap, wrap the threads with Teflon tape, and screw the cap on tightly.  Put the boat in the water, and check for leaks.

 

It will be a clean, simple, install, and uninstall.

This is perfect. Im going to give this a shot and let you know how it goes.

[Fishing Rhino]

Just for clarification.  Remove the extra ooze out before it sets.  You should end up with a 1/16th to a 1/8th inch thickness of silicone.  If you tighten it too much before it sets, it might end up leaking.  What you are doing is making a silicone washer.  Once it sets, you can compress it for a watertight assembly.