You can't dismantle any of the sailing vessels or the carts. You have to break them with your axe. To make sure that you recover all the materials make sure you have both the weight and inventory spaces to recover the materials, make sure taht auto gather is turned on, stand on the mast, chop with your axe. When the boat breaks you will drop into the water but all the materials will go into your inventory. (Your nails won't sink.)