Plug a transducer hole through hull

Ship Tzu

Member
Nov 29, 2008
89
London
Boat Info
Sundancer 250DA 1995
Engines
5.7L V8
Hi Guys, what what you advise?
I believe the hole is 75mm through 25mm ply hull, would you plug it with ply first, and how?
Or, would you fibre glass it throughout the hole?
I have to do this job before he goes back in the water, very soon!

Advise appreciated, I can't make up my mind.
Cheers,
Tony.
 
The hull should be solid fiberglass. There is plywood in the transom, but the hull bottom has no wood. However, if this is the original ducer, it's quite possible that there is a piece of plywood glassed to the inside of the hull (a "mounting pad"). If you're eliminating the ducer, you can eliminate the plywood mounting pad, as well.

Fixing it... honestly, the easiest thing to do is leave the old transducer in place. If that's not a possiblity you could use plywood to fill the majority of the hole, but can also (ideally) be done with glass and thickened epoxy. However, either way, you're going to grind both sides (outside and, ideally, the inside too)) of the hole to create an hourglass-type shape when looking at the hole from a cross-section viewpoint. The distance to grind it is about a 12:1 ratio. This is not simply a "glue a plug in the hole and go boating" type of thing. It will take good amount of time and effort to do it right.
 
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Thanks Lazy Daze, yes I think at least or this season I'll replace the transducer, I'm aware it's not just "plugnplay" lol.
Good advise, thanks again.
 
Or your other option is to install a seacock and plug it.
Good idea, but the problem is that the transducer is much larger in diameter than the thru-hull for the seacock. It would still require the same amount of glass work.
 

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