Thread: trunnels (tree nails)

Trunnels work well, but haven't the holding power of screws and no match at all for a through bolt. I use trunnels on occasion, mostly for alingment, but if ther's a strength requirement, perticularly in tension, then screws or bolts are the only consideration for me. Mast partners would be an area I wouldn't consider trunnels, again because of the types of loading. If the loading is in shear then trunnels can be employed safely.

Thanks Par,
Another thought I had is that small boats spend at least 90% of their time on trailers only getting wet occasionally. This could lead to shrinkage and loosening of the trunnell so, best used for larger "wet berthed" boats.

Trunnels were all that once were available to builders, so they got used. We now have evolved, even us old guys, into wonder materials and products, like screws, which is a relatively new invention, which is up from nails, which is also a moderately new contrivance. Trunnels were quite a step up from lashings, so they developed a fine reputation, but I know of no place on a boat where a screw or modern adhesive (read epoxy) can't do the job better in every regard.

I think the term is "Ludite" but, I still hand sew (with a "Palm") my own canvas sails and cook the boltropes in a pine tar mixture. I just love the ingenuity of the old builders who didn't have access to the materials we have now....
I have a plan for "Salle Rover", an extremely heavily built clipper bowed sloop.
The planking is 1.5" over 2" square ribs (the keel comes out of a 12"x12" 16' "log"). If I ever get around to building her, I will probably use trunnels for the planking....

What would happen to the preformance envelop of that boat if the massive planks and ribs where replaced with considerably thinner strips and no ribs? The weight savings could be placed in the ballast and this ratio would make a huge jump, permitting more sail area for the same wind strengths and angle of heel. You wouldn't need screws or trunnels.

I completely agree with you - the current rig is quite short and there is, on top of the weight of the keel, planking and ribs, 600 pounds of lead ballast under the cabin sole in way of the (Masive) center board.
However, for me, it comes down to the art of traditional carvel planking.
I know if Herreschoff were alive today, he would make use of modern methods - strip planking, double planking with epoxy and probably even plastic but, I just cannot bring myself to do it. I bought a router recently but, after using it once, came to the conclusion that the noise and mess it made simply did not make up for the speed. I am selling it and will continue using spokeshaves and beading tools for shaping. The only machinery I have is a thicknesser (I used to flatten boards by hand but, arthritis put and end to that), Table saw and Bandsaw.
I do use modern sealants and include a kind of gasket on the lands of clinker planks (a thin bead, you still get wood to wood contact but considering that these smaller boats spend over 90% of their time on trailors, they never spend enough time in the water for the seams to "take up") I also use epoxy to put the keel timbers together and attach the stem but thats it - I hate epoxy....

cheers

Warren

Originally Posted by PAR

What would happen to the preformance envelop of that boat if the massive planks and ribs where replaced with considerably thinner strips and no ribs? The weight savings could be placed in the ballast and this ratio would make a huge jump, permitting more sail area for the same wind strengths and angle of heel. You wouldn't need screws or trunnels.