Sheathing timber hull

Poida, epoxy will stick best, vinyl isn't bad, but generally is restricted to incorporating wooden members into 'glass structures (stringers, bulkheads, etc.)

There are other sealers as well. If using epoxy, entomb the individual piece with unthinckened goo. Use as many coats (I recommend three) as necessary to insure all the pores are sealed, with special attention to end grain and particularly porous areas. Many folks will use a specially formulated epoxy (penetrating epoxy, likes Smiths CPES) to seal the wood, which works very well and provides a good base for additional gluing, bonding, etc. with a laminating epoxy (regular epoxy). CPES (Clear Penetrating Epoxy Solution) type products are also a great primer for some types of paints. If I CPES an area that will eventually get paint, I typically use a compatible paint and skip the under coat of primer.

So, a raw wood part gets sealed with epoxy or CPES, then is assembled into the structure, regardless of fastening or attachment method.

This is when working with epoxy. For epoxy (or any hard plastic coating) to work as a sealer, it must encapsulate, embalm, entomb, completely cover every sq. inch of surface area, joints, cutouts, screw holes, the whole lot. If it doesn't, then moisture will get in and the wood will no longer be stabilized at a specific moisture content, which will permit gain or lose (swelling and shrinking).

Other sealers use different formulas and may require different techniques. The whole key is to stabilize the wood at a specific moisture content and lock out further ingress or drying. Any breaches in this coating will permit changes in the substrate under the coating. This movement (literally) will "sheer" the coating eventually and the coating will fail to perform its job.

A tip: avoid "porch and deck sealers" as a cost cutting measure. Most of these formulas are wax based, don't last very long and don't belong on a boat, though can shed rain off your back porch, down on the farm.

Brands01, an old trick to deal with worms is to lightly tack a healthy chunk of balsa to your transom, right on the water line, partly submerged. A 4" x 4" x 12" piece is easy enough to find (try the local hobby store). Do not paint it, just leave it for the worms, who will eat it up like a wooden buffet. When it's half gone, replace it with a new piece. Worms are like most things and will take the easiest, tastiest way to a full belly. If they have a choice between fresh clean balsa or anti fouling paint incrusted bottom planks, they'll generally eat the tender, select piece, before moving on to the gristle. Just keep an eye on it and insure they always have top sirloin and keep your anti fouling bottom paint in good shape, renewing with regular haul outs.

 

Great advice Par!

We've covered the sheathing on wooden boats topic - what are your thoughts about epoxy/copper antifoul paint - will this adhere properly to a wooden boat, or will the epoxy not bond properly with the damp timber?

 

Thanks Par

 

Epoxy (modified)/copper anti fouling paint is what is know as a "hard" paint or "contact leaching" paint. They are best used on boats stored in the water (moored or docked). It works by leaching biocides after contact with water. Pettit Trinidad is one of these types of paint and I've have good results with it. The Trinidad version has 70% Cuprous Oxide (the main killing agent) and Irgarol added to help prevent slime build up, especially along the water line. It's not cheap, but it does a good job on boats here in the semi tropic waters of central Florida and tropical waters of south Florida. You buy "hard" paints by their killing agent content, so the more the better.

Paint is more tolerant of moisture content then epoxy adhesives. I'm not sure of the exact moisture content recommended by the manufactures, but they have to formulate products for vessels that may not be out of the water very long. I suspect, if the planking is dry to the touch, clean and has a good scuffing (light sanding to provide some tooth) it will stick just fine. All brands will recommend a well applied primmer on raw or bare wood (of course) and this should be a few coats (I like 3 and 4 is better) of compatible primer, like an epoxy under coater.

 

Thanks again Par.

OK, if we can go back to the original question in this thread, I have more information to add, as I have now been and seen the boat in question.

Just to recap, 1953 timber sloop, 30 feet LOA, 8 feet beam, lovely lines. She is strip planked with 1" x 1" jarrah planking (Jarrah is a very very dense and heavy Australian hardwood).

The current owner believes that the planking has been edge-nailed and glued, ie, no caulking. It has about four broken frames/ribs (transverse) about 1/3 length of the boat from the stern. She is also leaking like a sieve through a gap where the seal is broken between two planks.

The owner bought her with the ribs broken, but it wasn't leaking back then. He has slipped her a few times to repaint the hull, and it seems to me that the planking probably opened up during slipping as the broken ribs didn't provide the necessary support.

Any suggestions on how to fix this?

 

I've moved this to a new thread "repairing strip planking" as the subject's changed.