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gondwanalon's avatar

Are you an expert boat painter? Can you solve with my Gel Coat problem?

Asked by gondwanalon (22146points) October 3rd, 2021
7 responses
“Great Question” (2points)

Last year I prepared a severely abused Hobie Cat 16 sailboat. One had 3 very large holes in the bottom. The other hull had a huge de-lamination area with manny holes. I spent 4 months sanding, and a lot of fiberglass and resin work. I sprayed 4 layers of wax-less gel coat followed by 3 layers of wax gel coat.

Sailed this newly repaired Hobie 16 several times last year. Stored it disassembled in my garage last fall, winter and spring I took the Hobie 16 out of the water after each sailing and stored it in my driveway. No gel coat bubbles noted at that time.This spring I moored the Hobie 16 at a freshwater lake and kept it there in the water for 3 straight months and sailed it several times this summer.

On October 1st I removed the Hobie 16 and took it apart to reveal the many gel coat bubbles many of witch contain water. Note that there were no gel coat bubbles in the areas above the water line,

After 3 months of sailing and sitting in the water one hull had about 1 cup of water and the other hull was dry. Yet both hull have the same amount of bubbling.

What do you think that I did wrong?
Did I not let the fiberglass hulls dry out completely before spraying?

See here

My plan now is to re-sand the hulls, open up the port holes, store them in the garage all fall, winter and spring and then re gel coat next spring.

What do you think?

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kritiper's avatar

You didn’t allow the hulls to fully cure/dry before applying the finish coats.

snowberry's avatar

What if you store them in a heated garage? that way there should be minimal humidity in the wood when you begin to paint.

canidmajor's avatar

I didn’t work much with gel coat back in the day, I did more with wood, but as part of that life I remember some of the basics. @kritiper is right. It needs to be stripped down again, then what my friend in the business called the “slow heat cure”. The more humid the climate, the more difficult, as that’s where the moisture builds up. If you have a dry basement, (better than a garage) have it heated to about 80–85° consistently for many months before re-coating them.

This info is over 30 years old (and worked well with some wood fittings and spars I had) so take it with a grain of salt.

Better yet, find some sites devoted to restoring old hulls, check with local marinas to see who might know of such a thing. The restoration nerds would love love love to help you out! I wish I’d had the internet when I was one such.

Good luck!

gondwanalon's avatar

Thanks a guys. But I may be kicking a dead horse.

I imagine that the fiberglass hulls could have many many cracks and pockets where water has been for many years. Could be very hard to completely dry it out. Previous owner let it sit outside for many years where rodents resided. There was lots of rodent nesting material and it was gross.

I’ve grown attached to this 1972 Hobie 16. Such is my love for this boat that give it another try.
Sand the old gel coat off, open the hulls up, put heating pads on them and a fan inside them for a few hours each day in my garage until spring. Then re gel coat.

snowberry's avatar

I vote for doing that in a climate (humidity) controlled facility rather than in a garage.

gondwanalon's avatar

@snowberry That’s the probably the best way to proceed. The cheapest local climate control facility is $78 per month for an 8’ x 23’ room. I wonder if they let you paint in the climate control rooms?

Last year I saw two Hobie Cat 16 on Craigslist for free (just come and haul them away) and there have been several for nearly free (I only initially paid $130 for my Hobie 16). You know what they say, “There’s nothing more expensive than a free boat.”. HA!

snowberry's avatar

You could try putting it in your garage, sealing all the holes to keep out humidity, and run a dehumidifier in there, along with a heater and air conditioner according to need. That would come pretty close to duplicating the climate controlled storage conditions.

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