EXPERIMENTS ON SIMPLIFIED SHIP FORMS. 



By Professor H. C. Sadler, Member of Council, and T. Yamamoto, Esq. 



[Read at the twenty-sixth general meeting of the Society of Naval Architects and Marine Engineers, held in 



Philadelphia, November 14 and IS, 1918.] 



The question of the simplification of ship forms is one that has received a good 

 deal of attention during the past year. In their anxiety to produce a simple form 

 from a structural standpoint, a good many designers, not familiar with ships, have 

 ignored entirely the question of economical propulsion. 



During the past year some experiments upon "straight frame" forms have 

 been conducted in the tank at the University of Michigan, and the results are thought 

 to be of sufficient interest to place the same on record. 



The main object of the experiments was to determine what difference in resist- 

 ance existed between an ordinary shipshape form and one in which the curved 

 form of the frames was replaced by straight lines. No particular attempt was 

 made to develop the best possible form, but the main features of the two types 

 were kept constant. 



The diagonal line representing the corner was in all cases made a straight line, 

 with the view that, if the bilge corner were cut off, this would facilitate construction. 



MODELS. 



The body plans shown in Figs, i, 2, 3, la, Plate 86, represent the various forms 

 used. The models were 10 feet long and 16 inches wide. For each particular type 

 the following characteristics were kept constant, viz., length, breadth, draught, dis- 

 placement (at load draught, with the corner cut off) ; the curve of sectional areas 

 (and hence prismatic coefficient), and the shape of the waterline. 



The models were tested at three different draughts covering the usual range. 



In each case the model was first tried with the sharp corner, and latterly this was 

 removed. 



Two different slopes were given to the bilge diagonal to determine the effect of 

 this feature. 



In one case also the lower knuckle was given a small enough slope to keep it 

 within the double bottom, the top knuckle in this case remaining the same as in form 

 (Fig. I, Plate 86). 



The following table gives the characteristics of all the forms tried: — 



