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 TM 55-1915-200-SDC
from general neglect. Other causes that will impair stability are deck icing in cold weather, excessive deck load,
overloading any area in general, improper removal of ballast, and free surface effect in tanks or bilges.
Section II. BELOW WATERLINE DAMAGE
2-3.
BELOW WATERLINE DAMAGE - GENERAL. Underwater damage may be from battle damage or from
collision damage caused by contact with another ship or by underwater obstacles, fixed or floating.
Below waterline damage to a hull resulting from collision, explosive device, or grounding might not cause a ship
to immediately sink or require abandonment but the following can occur:
a.
List.
b.
Flooding with sea water and/or fuel oil.
c.
Impairment of vital operating systems in damaged area.
d.
Fire.
The list of the ship can be presumed to be due to off-center weight. If the ship is underway when damaged and
the probability of receiving further underwater damage is possible, prompt removal of list is the prime consideration. List
has many undesirable effects:
a.
Impaired speed due to increased propulsion resistance, increased difficulty in operating the main
propulsion plant, and possible improper immersion of screws.
b.
Impaired maneuverability.
c.
Impaired overall stability due to list and improper trim.
d.
Increased difficulty in servicing and operating deck equipment.
e.
Ultimate swamping or sinking.
A combat hit which strikes the ship's side below the waterline can cause all the effects outlined above and, in
addition, may seriously decrease hull strength. A hit near the stern may damage or carry away one or both propellers
and can render inoperative or destroy the rudders and steering gear.
Damage causing total flooding of tanks or void spaces below the waterline, although reducing the reserve
buoyancy, may have a beneficial effect on stability if there is no list and sufficient freeboard exists. The amount of such
flooding that the ship can withstand depends upon the ballast and cargo distribution before the damage occurs. New
ballasting figures must be calculated using the methods
2-2
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