The Rot Doctor


Subject: Leaking Hull Problem
Date: Sun, 10 Oct 2004

Hello Professionals,

I have a huge project ahead. 38ft x 11 ft. wide 1941 Chris Craft (Cyprus hull) in the water now (leaking), but I plan to pull it straight up on 2 slings. This will give me about a foot or two clearance from the water. I plan to let it dry out for a week or two before trying to cover the bottom with something. Would you have detailed instructions for me for preparation and to apply polyurethane or epoxy or fiberglass or any other product. I will be working under the boat on my back on something that floats. Also please let me know how much of each material I will need. This will be a one man project in small sections at a time using about 2ft x 2ft. How much overlay do you recommend, etc. What about your Elastuff 120 100% Solids Polyurethane Coating and a topcoating?

Note : I will have to let it down in to the water when I move the slings to finish the area under them. Will this cause me any major problems?

PS if this is a bad idea to fiberglass over a wood hull in small sections please let me know.

Thank you,

Joe C.

Fort Worth, TX


You've got a big job ahead of you. First, I would not fiberglass over the hull given the method you are proposing. Fiberglass would not last over time without letting the hull get bone dry first. That is not going to happen in 1-2 weeks.

A flexible polyurethane would be much more advisable. You could get the hull dry enough to prime and paint in the time you are talking about. CPES as a primer, and Elastuff 120 as a waterproof membrane over top. You could paint the Elastuff 120 with any type of paint you like, including bottom paint.

CPES covers as a primer at 250 square feet per gallon. So you would need about two gallons to do the bottom. More if you intend to coat the sides of the hull as well. Elastuff 120 covers at about 100 sq. ft. per gallon, so you would need about 2 of our 2-gallon units to cover the bottom with one coat. Two coats is recommended, so you would need 4 2-gallon units to do the whole job.

I don't know why you are planning to leave the boat in the slings while working on it, but the job would be much, much easier if the boat was on dry land. Working on your back on a floating platform will be a very difficult way to work. Assuming that you go ahead with the sling method, when you go to lift the boat the second time in order to work on the sling areas, the slings will have to lift the boat in the green bottom paint/Elastuff 120/CPES. The slings will really stick to the fresh coatings, so I would not do this without covering the inside of the sling straps with wax paper, fastening them to the outside of the sling so they don't move, and then unfastening them when you are ready to put the boat back in. The wax paper will almost certainly stick to the hull, but this would be much better than the straps sticking to the Elastuff 120 and pulling it off the hull.

Come back if you have further questions.