Rebuilding a Clinker Speedboat

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Chyandra

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I am completing a major repair of a 40+year old clinker speedboat. It has not been afloat for about 14 years. It used to float at a mooring in the Clyde.

I only intend to launch it for day use, and I know it will leak like a sieve. So is it OK to use thickened epoxy resin between the planks and keep the mahogany timber dry, or is it best to launch it, let it fill and take up over a few days, then see if it is watertight.

At present it is bone dry after all these years and I am wondering if turning it over and sealing the bottom is an OK approach?

Any advice will be welcome. Chyandra
 
Chyandra said:
I am completing a major repair of a 40+year old clinker speedboat. It has not been afloat for about 14 years. It used to float at a mooring in the Clyde.

I only intend to launch it for day use, and I know it will leak like a sieve. So is it OK to use thickened epoxy resin between the planks and keep the mahogany timber dry, or is it best to launch it, let it fill and take up over a few days, then see if it is watertight.

At present it is bone dry after all these years and I am wondering if turning it over and sealing the bottom is an OK approach?

Any advice will be welcome. Chyandra
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I would not use epoxy. As it is a solid it it will pack out the planks as they take up. This will pull the nails and roves in and lead to a leakier boat in later years.

I would use a setting polyurethene sealant. Clean back the corner of the land about 6mm each face (outside!), PRIME with the CORRECT primer. mask up and apply a bead of sealant, smooth over and remove the tape. Paint over.

This will keep the boat dry, but won't damage it either if it stays in permenantly.
 
That's what I did with my clinker tender, which has worked very well.

Your "outside!" comment posses an interesting question though. Why not inside (assuming you can get a bead under the ribs)? A couple of advantages as I see it. The planks could then seal normally when exposed to the water, and critically for a clinker boat, rain water lying in the bottom would be kept out of the joint and therefore be less liable to assist rot. Comments?
 
Good point that. I haven't used my clinker sailing dinghy much this year and the last time I launched it took in a huge amount of water. (We'd had a long dry and hot spell)
In my case I would go for doing the outside joints as if on the inside joints you would see the sealant, it being on the top, exposed surface. As my boat is varnished a sealant bead would be obvious on the inside. It would also be easier to do the outside without all those annoying ribs to get behind. I cover the boat when out of the water.
 
Rebuilding clinker speedboat

Thank you both for your reply. I had not thought of polyurethane sealant but I do see the advantage. i intend to strip all the old varnish and antifouling off the outside and re varnish it from keel up. I guess there will be a transparent sealant.
Seanick your point about the correct primer is over my head, can you enlighten me please?

Chyandra
 
I found this whilst looking at sealants for clinker boat use.
If neither component is plastic and if you want to preserve your ability to disassemble the joint, use polysulfide.

Polysulfide is the most versatile of marine sealants. It is a synthetic rubber with excellent adhesive characteristics, and you can use it for almost everything. As a bedding compound it allows for movements associated with stress and temperature change, yet maintains the integrity of the seal by gripping tenaciously to both surfaces. It is also an excellent caulking compound since it can be sanded after it cures and it takes paint well.


However, the solvents in polysulfide sealant attack some plastics, causing them to harden and split. Specifically, you must not use polysulfide to bed plastic windshields or plastic portlights--either acrylic (Plexiglas) or polycarbonate (Lexan). Don't use it to bed plastic deck fittings either, including plastic portlight frames. Plastic marine fittings are typically ABS or PVC, and polysulfide will attack both. If you know that the plastic fitting is made of epoxy, nylon, or Delrin, you can safely bed it with polysulfide. Below-the waterline through-hull fittings are in this group, but when there is any doubt, select an

alternative sealant.


Polysulfide adheres well to teak (a special primer improves adhesion), and is unaffected by harsh teak cleaners, making it the best choice for bedding teak rails and trim. The black caulking between the planks of a teak deck is invariably polysulfide. For this application, a two-part polysulfide gives the best results. Polysulfide is the slowest curing of the three sealant types, often taking a week or more to reach full cure. Because it will adhere to almost anything, polysulfide has a maddening propensity to get on everything, so neatness is called for in using this sealant. Polysulfide sealants will have polysulfide printed on the package, or sometimes Thiokol--the trademark for the polymer that is the main ingredient of all polysulfide sealants regardless of manufacturer.
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From here http://www.boatus.com/boattech/casey/35.htm
 
Rebuilding a clinker speedboat

Thanks for that Lakesailor. It has given me sufficient info to know where to look next. I'll post a photo of the boat :)when I find out how to do it!
 
Hi and sorry to hijack this thread,

I've a 14ft clinker, Gaff rig I'm restoring. Its going well but I'm not confident to change the three planks that need replacing. Can anyone point me in the direction of a boat repairer specilialising in clinker in the south of England, (ideally Hampshire.

Thanks
 
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