Below waterline stopping compound

[andrewbodenham]

Time to get 'Valkyrie' ready for the season. 20' clinker hull. Recommendations please for the best stopping & filling compound to use over rivet and screw heads, and various minor cracks etc. below the waterline. She's been out of the water for a year, so it'll need to be something elastic to cope with the movement as the planks swell.
I'd prefer to use something out of a tin / tube rather than have to start mixing up my own potion.

 

[nmiller]

Try a one part alkyd filler, (e.g. International 100) or white lead paste mixed with putty to a soft cheese consistency for the nails and screws above the water line, and 3M 4200 below the waterline. Do not put anything in the cracks with a powder content. If she is going into SEA water, knife household soap into the cracks. It will not dissolve in salt water, and will squeeze out as the planks take up, if in fresh use tallow, but you will have to degrease the next time you paint her.

 

[cliffordpope]

Surely white lead has a powder content?
The traditional stopper is Stockholm tar thickened as necessary with lime, or hot pitch well brushed in. Both remain semi-soft and squeeze out as the planks expand. The first one can even be applied under water - if you find a significant leak, and can reach it from the water side, just squidge in a dollop.

 

[nmiller]

I specifically said do not use the paste in the cracks. Use soap in salt water or tallow in fresh. Mixing lime with the tar will also hold the crack open as it tries to close, making it worse.