Dark Hull Color Question

[Aaron_G]

Hi Everybody,

I've read a lot of discussion here about how a hull painted with a dark color can heat up to the point that the epoxy begins to break down. Yet I see a lot of pictures of CS 17/20s with dark hulls--anyone know how are they holding up? Has anyone actually seen a boat with a dark hull have problems?

I intend to fiberglass the outer hull of the boat and would like to paint it dark blue. I figure that here in Oregon, it seldom gets hot enough to worry about the Tg of epoxy. However, I also have visions of trailering my boat down to baja someday and don't want to look in the rear view mirror to see my hull peel off in big goopy mess.

[Aaron_G]

I asked the dark hull question to the tech-sales guys at System Three. Here was their response:

"You won't degrade the epoxy. However, Lopez Blue is dark enough so that the decks are going to get up to 170-180F on a hot July day at noon.This is above the Tg of the Epoxy. So the epoxy will be rubbery. The wood will try to lose moisture and shrink. The weave pattern of the fiberglass will print through along with the grain pattern of the wood. The deck will be too hot to touch. After a few weeks of this your boat will look very ratty. If you can live with the snickers of those who see it in this condition then paint the exposed deck and horizontal surfaces Lopez Blue..."

Of course, I only want to paint the hull sides and bottom dark, not the deck. Maybe I will just go for it and paint it blue anyway. If it looks bad...well, then I guess I will be doing a lot of sanding...

[Guest]

I have small hulls in the Florida sun and heat that has no delamination on them. In the tropics there are some problems, but in your case I would not worry about it.

There are some issues with dark colors and print through, meaning the webbing of fiberglass showing under the dark colors. Just don't use the 410 fairing compound under dark colors. Yes it works fine, but there are so many variables in homebuilding that itse best to stay away from using it. The 410 west system has some issues but its an exception and not the rule in way too many cases.

For fairing compounds from System Three, try :

http://www.jamestowndistributors.com/eserv/eclipse.ecl?PROCID=WEBDISP.WOEB.MAIN&SEARCH=quick%20fair&CLEV=5&PLEV=1&QLEV=1&PN=32515&ITEM.NO=1&PN.CT=4&TRACKNO=J1993076118&BANNERID=

This is the best going right now. It comes in larger containers.

[Charles Neuman]

I recently asked that question on the Woodenboat forum. Here's the thread:

Topic: dark paint colors over epoxy

"Post curing" is the process of raising the temperature of the cured epoxy near its point of softening. That is supposed to increase its ability to handle hot temperatures in the future.

I have also asked Joel Mill of Devlinboat (see his website at boatbuilder.org). He said that in the Pacific Northwest it's not a problem for the boats they build. In Florida he probably wouldn't paint a boat blue.

I plan to paint my topsides dark and the deck white, and I will keep the boat covered when it's not in the water. That should help.

Charles

[ZendoDeb]

If your boat has a cabin or any belowdecks accomidation a dark hull will be HOT HOT HOT. If you are going to be in warm weather - I am in Florida - you will be happy with white.

When I repaint my decks I am going with white, and an off-white for the non-skid. The PO painted the non-skid a light grey and it will take the skin off your feet in the summer.

The reason all the GRP hulls are white is that it just makes sense in warm weather.