To glass or not to glass entire bottom? Want opinions

[despotic931]

does the graphite layer of epoxy protect the lower layers at all? so if I did have any uv damage it would only extend to through the top layers with graphite, or would it damage all the layers right down to the wood? I hate to steal a thread, and if you want, Jaques, I can start a different thread on this subject.

[Laszlo]

...it does not protect from the UV's in theory but for some strange reasons, the epoxy does not break down on a graphite bottom.

Since the graphite is made up of discrete black particles, the area under each particle is shaded. With trillions of small black UV-absorbing particles suspended in the epoxy, there is probably very little resin that is actually exposed to the UV. I would expect that anything below the first few thousandths of an inch would receive no UV at all

Laszlo

[despotic931]

anyone have any pictures of a graphite bottom?

[MadRus]

I believe Uncle Ralphs HM18 has graphite on the bottom. See the gallery for pics.

-Dave

[UncleRalph]

anyone have any pictures of a graphite bottom?

Ralph

[despotic931]

Thanks uncle Ralph!

[ks8]

What about applying the epoxy Graphite mix over S3 primer? The primer would be protecting the underlying layers of epoxy/glass, so even if the UV got past the graphite layer, the primer would be the sacrificial layer and flake the whole thing off making priming and reapplication a little easier? Maybe?

sincerely,
ks

Hope you got your answer McPapa!

[Glewellyn]

The only possible problem I can see with priming and then applying the graphite/epoxy layer would be the primer compromizing the bond between bottom and top layers...

[ks8]

The only possible problem I can see with priming and then applying the graphite/epoxy layer would be the primer compromizing the bond between bottom and top layers...

That is sort of the intention. Since it was stated that once its on, its on. If there is a possibility that the graphite layer may suffer UV damage over time, and one would want to replace it, then the primer layer would become, as stated, sacrificial, so that over time, it would be easier and perhaps necessary to pull off the graphite/primer, but the idea was that, hopefully, the underlying structural epoxy/fairing would be unharmed.

Just a thought.

Sincerely,
ks[/quote]

[Oarelse]

I didn't glass the bottom when I built the boat. This spring I noticed that the boat bottom had develped deep checking in the plywood despite a generous epoxy coating. I sanded all the paint off and covered it with 0.5 oz cloth and have had no more checking. I imagine that 4 oz cloth would give a lot more protection, but I have had it on some rocky/gravely beaches and haven't had a hole poked in this light cloth yet.


Good luck,

Dave Hahn