Submarine Appliances And Their Uses
Deep Sea Diving, &c., &c.

TRANSVERSE SECTION OF SUBMARINE BOAT. Showing what happens when a vessel is holed high up, and when holed low down. Copyright. Fig. No. 46. BOAT HOLED LOW DOWN. Here the water entering compresses the air upwards until the pressure is equal to that of the water. It is obvious from our earlier remarks that the flooding of the boat in the above circumstances would have to be completed, as shown in first drawing on this page, before the hatch could be opened. This would be done by allowing the compressed air to escape through a valve provided. BOAT HOLED AT THE TOP. In this case the water would gradually replace the whole of the air in the vessel, hence the provision of watertight bulkheads to trap a supply of air at a pressure equal to that of the water at the depth at which the boat has foundered. In the case of a boat unable to rise through any other causes than those explained above, the vessel would, of course, have to be deliberately flooded to bring about the conditions necessary to enable the crew to escape to the surface.