Victor,
Thanks for the suggestion. I think the stuff I plan to use is similar to Line-X, but I'm not sure. I bought "Coat-It" from Goop, a waterproof epoxy sealer and protector. Supposedly you can use it for boat bottoms, truck beds, hatches and skylights, animal troughs, etc. The tree is a beech, and I've read that it preserves very well underwater (the early settlers used it for water wheels). My friends who have ponds said that the water line rots first since it goes through wet/dry/wet/dry cycles as the water level changes. So I'm most concerned about the water line and the part of the tree not in the water.
