AN ANALYSIS OF TESTS OF WATER-TIGHT BULKHEADS. 97 



such as a floor plate, a longitudinal or a deck beam, or else reinforcements 

 must be introduced. 



5. The bounding angles in all important bulkheads should be double 

 up to a height of about 5 feet below the load water-line. 



BXPLANATION OP BULKHEAD TABLES I AND II. 



The use of these tables is recommended only in case the bulkheads 

 are constructed in accordance with the above rules. 



As basic arguments of the tables are chosen the length of the stiffener, 

 /, and the head of water above or belov/ the top of the stiffener, h, both 

 measured in feet. 



With the construction of brackets here proposed I may be taken equal 

 to the entire height of the bulkhead except where, as may occur in a longi- 

 tudinal bulkhead, the stiffeners are bracketed to deck beams, in which case 

 I should be measiired from the underside of the beams. In any case l + h 

 is the total head at the foot of the stiffener, and it is assumed that the 

 stiffener is unsupported except at the ends. 



The value of h should be chosen so as to correspond to the deepest 

 draught to which the ship may presumably be immersed when in damaged 

 condition. This draught should be chosen with due regard to type and 

 size of ship, and to the longitudinal and transverse location of the bulkhead, 

 for if placed near the ends or near the sides it may become subject to greater 

 heads than when placed near half length or at the center-line of the ship. 

 Regard should also be had to the fact that the water in a flooded compart- 

 ment may be put in violent motion when the ship is pitching and rolling. 



Assuming the bulkheads to be constructed in accordance with the 

 above rules, the section modulus required for stiffeners with different given 

 values of /, h and s (span) has been calculated as follows: — 



Let the total load on one stiffener be denoted by P, then — 



P = jLC/j + IV tons, 

 35 V 2/ 



PI 



where h, I and 5- are in feet. The bending moment is taken equal to — , 



24 



which is very approximately the maximum near the middle of a stiffener 



fixed at both ends and under all conditions of loading. With brackets of 



the height required by above rules this maximum will be the absolute 



maximum everywhere in the free portion of the stiffener between the 



brackets. (See Fig. 3.) We obtain thus : — 



