PRINCIPLES OF NAVAL ENGINEERING 



weight and has the effect of so many tons placed 

 exactly at the center of gravity of the flooding 

 water. It is more likely to occur below the 

 waterline, where it has the effect of any added 

 low weight. Inasmuch as G is usually a little 

 above the waterline in warships, the net effect 

 of solid flooding below the waterline is most 

 frequently a gain in stability, unless a sizeable 

 list or a serious loss of freeboard results in a 

 net reduction of stability. The reserve buoyancy 

 consumed is the weight of flooding water in tons, 

 and the new GM and stability characteristics 

 are found as previously explained. 



Partial Flooding with Boundaries Intact 



The term partial flooding refers to a condi- 

 tion in which the surface of the flooding water 

 lies somewhere between the deck and the over- 

 head of a compartment. The boundaries of the 

 compartment remain watertight and the com- 

 partment remains partially but not completely 

 filled. Partial flooding can be brought about by 

 leakage from other damaged compartments or 

 through defective fittings, seepage, shipping 

 water on the roll, downward drainage of water, 

 loose water from firefighting, sprinklers, rup- 

 tured piping, and other damage. 



Partial flooding of a compartment that has 

 intact flooding boundaries affects the stability 

 of the ship because of (1) the effect of added 

 weight, and (2) the effect of free surface. The 

 effect of the added weight will depend upon 



whether the weight is high in the ship or low, 

 and whether it is symmetrical about the center- 

 line or is off-center. The effect of free surface 

 will depend primarily upon the athwartship 

 breadth of the free surface. Unless the free 

 surface is relatively narrow and the weight is 

 added low in the ship, the net effect of partial 

 flooding in a compartment with intact boundaries 

 is likely to be a very definite loss in overall 

 stability. 



Partial Flooding in Free Communication 

 with the Sea 



Free communication can exist only in par- 

 tially flooded compartments in which it is 

 possible for the sea to flow in and out as the 

 ship rolls. Partial flooding with free communi- 

 cation is most likely to occur when there is a 

 large hole that extends above and below the 

 waterline. It may also occur in a waterline 

 compartment when there is a large hole in the 

 shell below the waterline, if the compartment 

 is vented as the ship rolls. Where free com- 

 munication does exist, the water level in the 

 compartment remains at sea level as the ship 

 rolls. 



When a compartment is partially flooded and 

 in free communication with the sea, the ship's 

 stability is affected by (1) added weight, (2) free 

 surface effect, and (3) free communication ef- 

 fect. In general, net effect of partial flooding 

 with free communication is a decided loss in 

 stability. 



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