A dangerous but often necessary method of testing a compartment for flooding is to slowly slack off on the
hinged side of some of the dogs which hold a hatch or door closed. There is a slight amount of clearance around the
hinge pins, and as the dogs are loosened, any water present will begin to seep between the gasket and the knife edge on
the side. Control is still maintained by means of the hinges and the opposite dogs. This method cannot be used with
quick-acting doors and scuttles.
Crew members must not loosen the dogs on the edge of the door away from the hinges. To do so could result in
having the door buckle or fly open and another compartment would be flooded needlessly. Personnel casualty may
Secure every fitting after testing.
8-8. HOLES IN THE UNDERWATER HULL. As the damage investigation progresses, it may eventually come to a
bulkhead that has holes in it, cracked plates or seams, warped hatches, leaky stuffing tubes, or holes made by blast or by
fragments. By plugging these holes, it is possible to localize flooding and preserve buoyancy, and by the removal of
water from these compartments so made tight, further action can be taken to minimize the damage.
a. Water pressure. Water pressure causes difficulties when it becomes necessary to make repairs to underwater
holes although these difficulties are frequently overestimated. A hole submerged on one side only is subjected to an
inward pressure of 0.444 pounds per square inch for every foot of submerged depth. A hole 7 feet below the waterline
will be subjected to a pressure of 3 pounds per square inch. A circular hole 5 inches in diameter and 9 feet below the
waterline will be subjected to a total pressure of 78-1/2 pounds. These pressures are not excessive and they are reduced
if the hole is submerged on both sides.
b. Accessibility. The greatest difficulty in repairing underwater holes is often the lack of accessibility. If the inboard
compartment is flooded, it may be dangerous to attempt any repairs because to open a hatch or a door may permit
flooding in another compartment. It may be necessary to send a man down into a compartment, wearing shallow water
diving apparatus, so he may repair a submerged hole. This work may be hampered by hidden tangled wreckage in
darkness or water, and it is also difficult to work underwater with wooden shoring and other buoyant repair materials.
8-9. HOLES AT WATERLINE. Holes in the hull at or just above the waterline are dangerous because they may not
appear to be of immediate consequence. They destroy reserve buoyancy and, should the ship roll in a heavy sea or lose
buoyancy, the holes become submerged and admit flooding water above the center of gravity. This is dangerous
because this condition reduces stability and the flooding water invariably presents a large free-surface. As this occurs,
the situation becomes increasingly dangerous. These holes must be plugged at once, therefore, with priority being given
to holes at the waterline on the low side.