Wood and metal gave shipbuilders different buoyancy problems

Wood retained natural buoyancy even after seasoning, giving a wooden hull a useful material advantage. Iron and steel were denser than water, so the complete ship had to enclose enough volume to keep its overall density below that of the surrounding sea. Additional equipment and protection increased the weight that the hull needed to support, making that balance difficult even with modern calculations. Reported problems with Spanish submarine designs provide a modern comparison. Wood also gave builders options for reshaping, steaming, and replacing parts as they sought a larger, more stable hull that could still move efficiently through the sea.