96 AN ANALYSIS OF TESTS OF WATFR-TIGHT BULKHEADS. 



additional 4-feet depth or ji inch for each additional 5 -feet depth. For 

 plating above this water-line the weight should be decreased at the same 

 rate. The thicknesses determined by this rule should be considered as 

 minimum thicknesses, and must in many cases be increased to provide 

 for corrosion, for general or local structural strength, or for the forces to 

 which the plating may be exposed by the stowage of cargo. 



Below the normal load water-line both butts and seams should be 

 double riveted. 



3. The stiff eners should be single, i. e., each individual stiff ener should 

 be placed on one side of the bulkhead only. On all stiffeners of any impor- 

 tance a face bar or a reversed bar should be fitted on the free flange so 

 as to balance as nearly as possible the strip of the bulkhead plating, which 

 may be assumed to work with the stiffener. 



A more efficient solution could be obtained with bars of sections as 

 indicated on Fig. 5, where one flange is heavier than the other. 



FI&. 5. 



T T 



BUUKHCAD PuATlKia- 



This would obviate the necessity for face plates or reversed bai'S, but 

 it is a question whether such bars could be rolled without too great extra 

 cost. 



With the thicknesses of plating recommended above, the spacing of the 

 stiffeners should not exceed 4 feet. The stiffeners should all be placed on 

 tlie same side of the bulkhead. 



4. The stiffeners should be provided with efficient brackets both at top 

 and bottom, constructed as indicated on Fig. i , c by splitting the main bar 

 of the stiffeners, whether I , D , X bars or bulbs. The face plate, if any, 

 should be continued the whole length of the bracket and should have a 

 good end connection. The height and width of the lower bracket should 

 be about three times the depth of the stiffener, but in no case should the 

 height fall below one-tenth of the length of the stiffener. The sides of 

 the upper bracket may be about ten per cent, shorter than those of the 

 lower bracket. 



The brackets should be attached to a rigid part of the ship's structure, 



