You are the Canadian version of Mark Twain! He happens to be my favorite author, so take it as a high compliment. My middle name happens to be Mark. I grew up in the Mississippi Delta where my grandfather built and raced boats on the Mississippi River. I wish he were alive to hear both your story and Etienne's poem.

Well it sounds quite far-fetched, but there is some truth here. The sap does rise and fall in trees and it has long been said you should fell trees on a waning moon. In Caricou they build wood boats by hand and they fell the trees just after full moon. http://www.tradition-sailing.com/carriacou-sloops.html I have seen these boats and they sail amazingly and are very seaworthy. If he built his boat using lapstrake construction, lapped each strake appropriately, and clenched it tightly, he could build a boat without glue. Not all lapstrake boats are glued. Also if he used carvel planking he could achieve the same goal but I am sure the caulking required in carvel planking would be considered sealing the hull and would negate the man's story. With either construction, however, what really seals the boat is when the hull is wetted the wood swells. Any would-be leaks are basically self-sealing as the wood swells up when wet and fills the leak. I think actually what the man's father did was fell the trees when they had LESS sap. Trees with less sap are lighter, and they also have more absorption and thus will swell more when wet. However the downside is they are less rot resistant and bug resistant so who knows- it could go either way!

That said, I have a friend who is quite a gardener and she swears that you should plant at full moon. She will be out at midnight planting her garden. I have to say, you can't argue with the results she gets. Finest garden around!