The crew reasoned that sufficient buoyancy in the after section could tilt the sub on her nose and extend the stern above the surface. The tilt would cause the water in the motor room to drain forward and increase buoyancy further. However, there was great risk involved because this would allow salt water into the battery room, which would generate deadly chlorine gas. They hoped to have enough time, after the water had entered, to close the watertight door before the gas could reach a dangerous level.