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 TM 55-1905-223-SDC
No compartments are provided with sounding tubes. This is no bar to investigation, however.
Tapping on a bulkhead with a hammer will often disclose the presence of water on the other side; the exact
height of the water may be judged by variation in the tones produced when the bulkhead is struck at different
levels. Repair team members occasionally should tap various bulkheads for practice to train their ears to the
sound of bulkheads around undamaged areas. The tones will vary appreciably with the thicknessoftheplate.
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 result.
Secure every fitting after testing.
8-7. 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.
8-8. 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
8-4
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