waterline is only subjected to a water pressure of about
underwater holes tends to be more difficult. Therefore,
3 pounds per square inch.
any Damage Controlman who can repair underwater
damage must certainly be able to repair similar damage
Figure 8-1 shows the flooding effect of unplugged
above the waterline. For this reason, most of the
holes and of the same holes after inserting simple plugs.
discussion in this chapter will deal with the repair of
The volumes of flooding water are given in gallons per
underwater damage.
minute. The number of electric submersible pumps
required to handle the flooding is also shown. It should
FACTORS AFFECTING UNDERWATER
be obvious that prompt plugging of holes is desirable. It
REPAIRS
can save the ship, it releases pumps for use elsewhere,
and it saves wear and tear on the pumps that are in use.
The primary factors that make it difficult to repair
Note that the pump capacities used are considerably
underwater holes are as follows:
under the rated capacity, usually 200 gpm. However, if
1.
The pressure exerted by the water
the pump strainers get clogged with debris, the actual
2.
The relative inaccessibility of the damage
capacities may be much less than the rated capacity.
The difficulties caused by water pressure are often
The greatest difficulty in repairing underwater
exaggerated. Actually, a hole 7 feet below the
damage is usually the inaccessibility of the damage. If
FOR COMPUTING THE AMOUNT OF WATER THAT
COULD ENTER A SHIP THROUGH A HOLE IN THE
HULL AT ANY ONE INSTANT IN TIME, YOU MAY USE
THE FOLLOWING FORMULA.
Q= 0.6A
2 GH
WHERE Q = CUBIC FEET OF WATER/SEC
A = AREA OF HOLE IN SQ FT
2
G = GRAVITATIONAL CONSTANT 32 FT/SEC
H = HEIGHT OF WATER IN FEET (DEPTH OF HOLE)
.6 = COEFFICIENT OF DISCHARGE FOR SHARP EDGED HOLES
"PUMPS" ARE THE NUMBER OF ELECTRIC SUBMERSIBLE
PUMPS REQUIRED TO HANDLE THE FLOODING
UNPLUGGED HOLES
SAME HOLES PARTLY UNPLUGGED
DEPTH GALLONS
DEPTH GALLONS
PUMPS
PUMPS
IN
IN
PER
PER
FEET
FEET
MINUTE
MINUTE
301
1
1
114
1
3
160
425
2
2
4
5"
192
512
3
3
2
227
603
4
4
5
676
5
5
254
6
277
739
6
6
286
794
7
7
3
7
320
853
8
8
904
9
339
9
AREA OF HOLES = 19.65 SQUARE INCHES
AREA OF PLUG = 12.25 SQUARE INCHES
DEPTH GALLONS
DEPTH GALLONS
AREA OF LEAK = 7.40 SQUARE INCHES
IN
PER
IN
PER
PUMPS
PUMPS
FEET MINUTE
FEET MINUTE
3
1
1
319
91
1
451
129
2
2
4
158
3
3
552
5
638
182
4
4
713
204
5
5
2
6
782
224
6
6
241
7
7
844
7
258
8
8
902
273
9
9
957
3
8
2. THESE FIGURES SHOW HOW IMPORTANT
1. NOTE:
3. AREA OF HOLES = 21.0 SQUARE INCHES
AVERAGE EFFECTIVE FLOODING
IT IS TO PUT SOME KIND OF PLUG INTO
AREA OF PLUGS = 15.0 SQUARE INCHES
AREAS SHOWN WITHIN WHITE
ANY HOLE RIGHT AWAY. ALL QUANTITIES
AREA OF LEAK = 6.0 SQUARE INCHES
LINES.
ARE APPROXIMATE.
DCf0801
Figure 8-1. Flooding effect comparison; unplugged holes vs. partially plugged holes.
8-4