Thru-hulls, seacocks 1st timer....ping Maine Sail

Maine Sail · Mar 19, 2011

sailmakered said:
First I want to thank you for the GREAT tutorials!!! I was a sailmaker years ago but never got much experience in the maintenance of keel boats. 4/1/11 is the first haul out for my new to me 78 Cat 27 and I'm trying to get my ducks all lined up.

I am going to install flanged seacocks on the 4 existing thru-hulls. I want to use the alternative method of bolting just through the backing plate. I plan to use 5/8" FRP and wonder if thru-bolting the backing plate versus tapping would work? I could countersink the hull side of the backing plate for the bronze flat head bolt and epoxy the bolt in the hole to keep it from spinning. Any thoughts?

You noted you use 3M filler to fair the outside of thru-hull installation. This seems to be a thickened vinyl ester system and is pretty high priced. What would be the problem with using a thickened epoxy filler instead? The epoxy route seems to be more cost effective and less water permeable.

Thanks
Steve
S/V Judy K II

The reason I don't prefer bolts in the backer is if they spin or corrode or strip. If they do it's a big job to fix. I have alternatively used a forstner bit and sunk and epoxied a bronze nut into the back side of the backing plate then epoxied it in place. This still allows for removable studs and a captive epoxied in place nut. It works well but is a little more work than just taping or countersinking machine screws.

The 3M vinylester is a great product and many "blister specialists" use and prefer vinylester over epoxy for barrier coating. vinylester is very, very moisture resistant. I like the 3M because it kicks fast and is sandable in about 30 minutes making for a quick job. Yes it's pricey but you're not using much. Epoxy works too just don't use Bondo..