Failure of a bulkhead may occur, however, from one of the following causes:
a. If the structure is old, it may have been subjected to considerable corrosion and so be weakened.
b. The damage itself may cause some local weakening of the structure; this is particularly liable to occur for those
structures close to an explosion.
c. The static pressure due to flooding may be increased by a dynamic pressure due to the ship's movement, either
by ship speed or behavior in a seaway.
Unless one or more of the above conditions exist, there should be no necessity for shoring bulkheads or decks.
Shoring is not required as a matter of routine.
The third factor has to do with the effectiveness of the shoring itself. In cases where it is necessary, the extent of
shoring sufficient to be of any value will be such that the operation will be a major one. Shoring cannot be effectively
provided in a period of a few minutes or even in an hour. Two or three shores placed at random will be of no value
whatever. Effective shoring will consist of a reasonable complete network of reinforcement.
It is apparent that no hard and fast rules can be given as to when shoring is necessary, nor can any set methods of
shoring be established in advance.
Whether or not shoring is required is a matter of judgment, with consideration being given to the known state or
preservation of the bulkhead before the damage, the probability of its having been weakened by the explosion, the load
on the bulkhead as evidenced by its appearance and action, and existing or probable dynamic forces working on the
critical area. For riveted bulkheads, it should be safe to assume that until considerable leakage occurs around rivets or
through seams, the bulkhead needs no shoring.
Section III. METHODS OF SHORING
7-3. METHODS. The methods and extent of shoring are likewise matters of judgment. The following principles,
however, should be followed:
a. Bulkheads should be shored to decks either through obstructions on the decks, such as stanchions, hatch
coamings, etc., or through the beams overhead.
b. Pressures should be distributed over as wide an area as possible to avoid local failure.
c. Every effort should be made to avoid damaging the caulking around bulkheads.