This doesn't surprise me at all, and it shouldn't surprise anyone who knows anything about the construction of wooden ships. Look up the history of the Eddystone Light, the first lighthouse built in open sea. The first wooden tower failed immediately, but the second (Rudyard's Tower) was built of wood in 1709 by a shipbuilder who knew how wood should flex and how to make solid joints that could take the ocean's pounding. It was perhaps eight or nine stories high and took everything the Atlantic could throw at it for fifty years until it burned down, something the designer couldn't have done much about. It was replaced in 1759 by a granite tower (Smeaton's Tower), which lasted until 1877, when the rock underneath it began to crumble away. The current Eddystone Light is basically a scaled-up duplicate of it. (The top 3/4 of Smeaton's Tower was disassembled block by block and reassembled on Plymouth Hoe, where it is a tourist attraction. The stub is still on the original site beside the new one, and it still hasn't fallen over.)