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seacock replacement - looking for backing block material

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bobct

Advanced Contributor
Do any of you guys have any fiberglass laying around? I need to make up some 3/4" backing blocks, I'm replacing my engine seacocks. I would love to use solid fiberglass so I don't have to worry about glassing in marine plywood (unless that's a better option).

A couple of 3/8" thick pieces of solid glass (epoxied together = 3/4") was what I'm thinking.


Bob
 
I have FRP sheet in 1/4", but that is a bit far from 3/4. I would go to a neighborhood machine shop, and buy a 3/4" rectangle of either delrin or maybe polycarbonate. Avoid PVC. Do you really need a backing block? Is the hull cored or wood?
 
it's a solid glass hull. There's a backing block there now so I'm just replicating what Trojan did at the factory. I like the idea of Starboard but I get mixed reviews on whether it should be used. I know nothing really sticks to it (4200 etc.).
 
I was in a similar situation a few years ago and settled on 3/4" exterior grade plywood for backing blocks. I coated the blocks with epoxy paying partilcuar attention to the edges of the plywood to prevent delamination. After two years there is very little evidence of decay or degradation.


As you mentioned, Starboard and other high density polyethylenes are not good choices because they have very low surface energy (nothing sticks to them except a few high priced two part acrylic adhesives).

Best wishes,

Tom
 
Bob, any consideraton for Teak, Ipe, Lapacho......... or another oily exotic hardwood?
Your sealing will be done externally.

.
 
Jeff,

That would be great, I'm happy to pay you, it'll save me some time. I need to get roughly two 5" (assuming it's 3/4") circles out of whatever you have. Can you shoot me an email when you get a minute?

thanks,
Bob

[email protected]
 
You can use regular exterior plywood if you do the epoxy encapsulation thing. Mix up a batch of your favorite resin and thin it 50% with Xylene. Sop that onto the plywood until it won't soak in any more and let it set up over night. Repeat the next day (you won't need nearly as much glop). This will completely seal the wood forever and makes it into a "high tech" composite. I like to round all the edges with a 1/4 rounding bit in the router.
While you're at it make yourself a few extra blocks of various sizes. You can use these for a lot of things....very handy to have.
 
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