Help with Print-through Problem In The Hull

[Ilan Voyager]

Lucas, you're wellcome.

I agree with you. I doubt that under a dutch's summer sun the hull would be likely to soften. The deformation was about a small boat kept under a closed metallic hangar in the south of France. You have not been lucky with your "70 degrees resin" as you took all the needed precautions.

Here in Cancun we have ultraviolets 12+, sometimes 42 degrees in the shade, and I've measured 93 degrees celsius on a dark grey gelcoat of a deck...The sun can give us 6.5 kW/m2/day.That's a hot post curing!!!! Dark colors forbidden.

I have had the worst problems with a white filler made of a copolymer who litterally melted and expanded like pop corn in the French Riviera's sun. I think that the hollow microballoons fillers may be problematic, as they have a gas inside ready to make bubbles, so I use solid fillers.

I know that a lot of clients want dark colors. It's always the same discussion with them. Dark colors, browns and greens don't age well in sea, they become yellowish. It's true that for example ocean blue with gold stripes is very elegant but I think that may be deadly; it's almost impossible to search a blue hull in sea.

My little experience as officer in the navy dictates that bright light colors as whites, yellows and reds are easier to find in a rough sea and grey weather. After the unsuccessful search of a capsized small fishing boat (we passed just very close without seeing it) I decided that all the boats I'll build will have bright orange antifouling and white pearl hull...the fishing boat had a darkish blue antifouling, and black hull. Four dead by hypothermia.

You're also right with the sprayed coat. I've already been said that an even coat of epoxy seems to control the problem of print out. I have always done that (tincted in white) with the other purpose to control the wet sanding and the filling made in another color.

[seamonkey]

....lucas--I am of the same opinion as you-that gelcoat is not a good product to use for it's porosity,weight,etc,,except for it's convenience in mass production,,,,,but if you are making an epoxy product from a mold,what are the options other than post-finishing the product?

[seamonkey]

[quote=lucas adriaanse]Seamonkey, no we never use gelcoat on an epoxy boat ....

.....as far as I am concerned,,the only reason to value gelcoat at all is in it's 'manufacturing efficiency',rather than it's physical properties.So you post finish your products?this certainly would be a very good way to avoid print-through and get a very nice finish,,but of course very expensive.

[lucas adriaanse]

Seamonkey, we build one offs (prototypes) in epoxy, faired with fillers, then painted and polished. The series productions from female moulds are in vinylester with gelcoats, for economical reasons. Indeed, post treatment is far too expensive; you wouldn't make any money trying to sell yachts built like that. There are very good gelcoats, even tougher (scratches) than the best 2C paint systems. As long as you give the bottoms a good osmosis prevention system.

Ilan Voyager, dark hulls should at least have white antifoul. Orange on white hulls would be better, but hey ... the customer .....
You know how it is with most of them.

Lucas