Caulking
No silicon or synthetic caulk should be used on the batteau. Cotton or oakum is packed into the cracks and when the wood swells this fills any gaps which would have remained. It is remarkably effective and works better than any of the silicons which have been tried by individuals in the past. Since wood swells across the grain and not lengthwise, the caulking is even more important on end butt joints than it is on edge joints which will hopefully swell tight on their own. Experience has shown that butt joints along with joints where the nose cone meets the body of the boat are the primary culprits to be examined when the boat is leaking.