Seacock backing pads, WBP plywood?

I have a plastic thruhull log transducer in my plywood hull with ply backing pad. The hole is a clearance diameter, edges sealed with epoxy and plenty of sealant. Been there for 15 years at least with no problems.
 
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I've seen at least one, but I do have a bad habit of looking at fairly sordid boats!
Well that's one from an admitted sordid source (not the poster!) - but in reality I suspect that the problem is close to the square root of diddly squat.

might I suggest that in the real world of boats that go sailing plywood backing pads are perfectly acceptable - but its always a good idea to use some common sense and epoxy coat them and/or paint them!
 
Well that's one from an admitted sordid source (not the poster!) - but in reality I suspect that the problem is close to the square root of diddly squat.

might I suggest that in the real world of boats that go sailing plywood backing pads are perfectly acceptable - but its always a good idea to use some common sense and epoxy coat them and/or paint them!

I wouldn't describe my boat as sordid :)

Thanks for all your replies, I taken on everyones points of view. I reckon a layer of epoxy and a layer of bilge paint will probably be my course of action
 
I have lost count of how many backing plates I have installed for clients over years but one thing I always do is avoid using ply or timber.

Cutting board plastic is fine but it should be tapered around the outer edges and fully classed in.

The alternative is to use only fibreglass, placing the smallest patch first and then each additional patch is slightly larger, use a straight edge to get a perfect pad.

Remember, the object is to provide a flat seal for the thru-hull fitting that flexible enough to not damage the hull in the event it gets hit or snagged.

If God wanted us to use timber in wet situations he would have created a waterproof wood.

Good luck and fair winds. :)
 
If God wanted us to use timber in wet situations he would have created a waterproof wood.

I thought He had: Lagarostrobos franklinii or the Huon Pine. It grows well in Tasmania, it's just a pity the trees take 1000 years to reach maturity, so there's a problem with sustainability ....
 
So does this mean that wood is an unsuitable material for making boats of then? ;)

Yes in sea water it gets eaten by worm and in fresh water it rots.

The boat I had when I lived in the UK was wood so this time its steel.

IMHO the in the long term cupro nickel is the absolute best material to built a boat from except for the cost.
 
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