Looking at this fascinating plan you will discover why the damage to Titanic’s hull led to the ship sinking. Bulkheads are steel walls in a ship that divided the hull into watertight compartments. Both Olympic and Titanic were built with fifteen bulkheads each but these did not reach the top of the hull. If more than two compartments flooded, water could flow over the top of one bulkhead and flood the next compartment.