rehab question

[Christensen]

A friend gave me his Sunfish (actually, a Scorpion, built by the Columbia Car Corp., in Charlotte, NC) a few days ago. The hull had been sitting in his backyard for approx 20 years but appears to be in very good condition structurally. The sail was stored indoors and looks fine.

While scrubbing it down yesterday, I noticed several fingernail-tip size cracks or blisters in what appears to be an outer skin on the hull. Am I correct that there is an outer skin on the hull? If so, is there any way to fix these cracks/blisters? Do they matter?

Thanks for your help.

 

[Christensen]

Am I correct that there is an outer skin on the hull? If so, is there any way to fix these cracks/blisters? Do they matter?

Thanks for your help.

Sorry about the double post but I couldn't figure our how to edit the prior post. (There was no edit button). On the bottom of the hull, I now see that the cracks/blisters are in the shell that covers the actual fiberglass. If I pick at one, it shows the fiberglass underneath.

 

[DanB]

Assuming the Scorpion is of fiberglass construction then its makeup consists of a gelcoat layer over layers of glass fibers incased in polyester resin. It helps to understand gelcoat is actually a type of polyester resin too only it usually carries no glass fibers and instead is pigmented for cosmetics. Fiberglass boats are built in a mold where the gelcoat is sprayed in first. After a partial curing the glass fabric and resin gets hand laid on the gelcoat so it forms one amorphous resin mass with reinforcing fibers running throughout the non-cosmetic portion. One trouble that could be a source of your problem is when air bubbles get trapped during the lay-up process. Later in the life of the boat these show up as gelcoat blisters. ( http://www.fiberglass-repair.com/rshop3.html )

Another source of blisters is water. Fiberglass resists water penetration well, but isn’t absolutely waterproof. With time moisture can seep through the gelcoat and cause separation. On the surface this is expressed as blisters. Deeper penetration and you get soft spots marking delamination in the glass fabric layers. These beach craft are thin for light weight so they don’t react well to continuous immersion as in mooring. That doesn’t stop some sailors from tying up all season and your boat may have this treatment as part of its history. Sitting where water is allowed to collect in a footwell or condensation is trapped under a tarp can have a similar affect. Worst, I think, is when there’s a leak and the boat sits for ages with water inside the hollow of the hull.

Discerning Sunfish owners check their hulls for leaks ( http://www.windline.net/proj4.htm ) and take steps to keep the interior dry ( http://www.windline.net/project1.htm ) to avoid blisters and other wet boat related problems. These steps may help your Scorpion too.