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198 he i; TTT. L ; Me A ee SE Ose 5.81 5.81 5.81 B B MEE EGC Nr OK cco > 3.0 3.0 230 d Block coefficient ..... 0.814 0.804 0.782 Prismatic coefficient... 0.831 0.821 0.798 Midship section coeffi- CHEE Spee aes 0.980 0.980 0.980 The curves of residwary resistance are shown in Fig. 4. The effect of even a slight modification of form is seen by comparing curves 1 and 2. For a reduction of displacement of 1.25 per cent there is a correspond- ing reduction of about 10 per cent in residuary resistance at speed-length ratios of between 0.60 and 0.70. In the case of a 300-ft. ship this would mean a reduction of about 100 I. H. P. at a speed of nearly 10.5 knots. The effect of a still further reduction is seen by comparing curves 1 and 3, and in this case the saving would amount to nearly 300 I. H. P. at the above speed. In both the above cases it should be remembered that, al- though the displacement is decreased, there is a corresponding decrease in 'weight of machinery land coal, and the balance from a commercial stand- point might sometimes be in favor of the finer vessel. Attention is also called to the fact that, although the residuary resist- ance per ton of displacement shows somewhat small differences, the dis- placement also decreases, and hence the reduction is greater than appears from the curves. The wetted surface also is slightly decreased. ; The next series represent a nar- rower type and.one approaching more nearly the ordinary lake freighter. The body plan and sectional area curves are shown in Figs. 5 and 5a. The particulars of the model are as fol- lows: ao 8; == 2.143; oe fs Ge Block coefficient = 0.855; Prismatic coefficient = 0.869; Midship-section coefficient = 0.984. ihe forms 18.18 and 28.25" are taken from the paper read last year, and call for no further comment. They . tare added for the sake of comparison with further modifications of tthe bet- ter of the two forms, viz. 2B.2S. The modifications in general are shown by the hatched portions on the body plan. First--The lower parts of the bow sections were reduced. Second--The same thing was done with the after sections. Third--The amount cut from below was added The Marine REVIEW Moon A. # Fig t Moore. B Pe " Mooer FS.