the latter types, the effect of shallow water on performance would also be a matter of special 

 interest. The availability of such systematic information would provide the naval architect 

 with much basic and background information and greatly reduce the need for routine model 

 testing. 



The results presented in this report are for models tested for resistance and propul- 

 sion in smooth water only. They co\er the major features of single-screw merchant ships 

 such as proportions, fullness, LCB position, and variation in propeller diameter. They ,, 



enable a designer to obtain very quickly from contours a lines plan having the correct dimen- li 

 sions, displacement and LCB. Moreover, because of the graphical relationship between the 

 models, he can also associate with these lines a close estimate of resistance and shaft 

 horsepower. As pointed out earlier, although no claim can be made that such a design is an 

 optimum one, the comparisons made between Series 60 and new successful ships indicates 

 that it will be of a reasonably high standard. j 



When the series was begun, the hope was expressed that it would provide an accept- 

 able starting point for additional series planned to in\estigate many other facets of the hull 

 design problem. This hope has been realized to a very considerable extent— models of Series 

 60 have been used for a number of comparisons of models in waves, sponsored by the ATTC 

 and the ITTC, for a methodical investigation into launching, and for calculations of the forces 

 on ships in a seaway and their responses to such forces. They have also been used in 

 studies of wavemaking resistance and of the effects of adding different sizes of bulb at the 

 bow upon resistance and ship motions. As described in this report, the Series 60 parent 

 models have also been used for the measurement of wake patterns and the resultant propeller 

 forces, and for the median model of 0.70 Cg , the effects on these and upon resistance and 

 propulsion of changes in shape of stern sections from U to V have also been evaluated. 



Probably the most urgent need for extension of this methodical series work lies in 

 the realm of seagoing qualities. It by no means follows that the hull form chosen for good 

 performance in smooth water will be equally successful in waves, either as regards mainten- 

 ance of speed or minimum ship motions. This applies particularly to the fuller, slower ships, 

 where the absence of any significant wavemaking calls for full bows and slender sterns to 

 achieve good smooth-water performance. A methodical program should be carried out first, 

 to test key models of the series in waves, and "this should include experiments to find the 

 effect of LCB position upon maintenance of sea speed. The next step would be to evaluate 

 the effects of changes in section and waterline shapes, both below and above water. These 

 would include, for example, an examination of the relative merits of U- and V-sections, and 

 the best type of above-water form at the bow to ensure a clean, dry ship by the provision of 

 adequate freeboard and flare. An extensive program of experiments of this kind, based on 

 Series 60 models as parents, has been designed at the NSMB. The results of some tests 

 have already been published, but much yet remains to be done. 



XIII-2 



