Cracking Hull

cracking
Originally uploaded by Phil_Parker.

If you are going to sail a cardboard hulled boat, you better make sure it is waterproof.

The instructions say everything should be painted with urethane. Fine, except that I don't know where you buy it. On the other hand many varnishes are marketed as polyurethane so I assume this will do.

First step was to spray the hull with Plasticote varnish. It went on well and seemed to make the hull slightly glossy which I think ought to keep the water out. Unfortunatly it didn't cover the areas where the surface of the card had been damaged when I peeled off the tape used to hold it together for the first fixing.

Filler is the cure for this and on the garage shelf was some high-build primer. This is a primer with filler in and it's in a spray can, Just the job. I think I bought it for working on my camper because I couldn't get any normal stuff at the time.

Anyway, I spray away. Remembering previous tangles with this, I dried each coat with a hair dryer. It all looked OK except for a couple of areas where the paint went on too thick. These were a bit rough but I decided to let it all harden and sand the problems away.

To my suprise when it had dried some areas were cracked. Sanding took the worst of this away but another think coat and some more drying brought the cracks back. Presumably the filler is too think and shrinks on drying.

I'm going to sand again and if it looks OK shoot another coat of varnish over the hull to finish the job. Before doing this I've attached the deck so the hull has reached its final shape just in case flexing it makes things worse. At least the tape marks have gone...