CHAPTER XII 



REVIEW OF SERIES 60 PROJECT 



In the design of any given ship the naval architect has always to meet a number of 

 conflicting demands which, to a greater or lesser extent, limit his choice of dimensions, 

 proportions, fullness, and other features. An increase in length is generally favorable from 

 the points of view of low resistance in smooth water and maintenance of speed in rough 

 weather, but it is expensive structurally, carries penalties in crew numbers, and, in specific 

 cases, may be limited by dimensions of locks, piers, drydocks, etc, which may also restrict 

 beam and draft. The depth of water in the world's harbors today is also a definite limitation 

 on draft, particularly for large tankers and other bulk carriers. On the other hand, beam is 

 limited on the minimum side by the need for adequate stability, and questions of trim and 

 weight distribution, especially in bulk carriers, may exercise some control over the necessary 

 longitudinal distribution of displacement and so on the LCB position. 



In practice, therefore, the naval architect has usually to design a ship within dimen- 

 sions already defined to a large extent by such considerations^, but there is generally some 

 latitude available for adjustment to suit the demands of good resistance and propulsion 

 qualities. 



The results of the Series 60 experiments can be of material help to the designer in 

 any single-screw ship design which in its proportions and other features falls within the 

 area of variables coyered. If the designer adopts the lines of Series 60, the position of LCB 

 as used in the parent forms, and a propeller having the standard ratio of diameter to draft of 

 0.7, he can make a very accurate estimate of both the ehp and shp of a ship for any particu- 

 lar selection of length, beam, draft, and displacement; 



If for trim or other reasons, the LCB has to be placed in some other position, allow- 

 ance for this can be made using the data given in Chapter VII or in Tables 49 through 53, 

 and for departures from the standard propeller diameter the values of w, t, and relative 

 rotative efficiency (e^^) from the contours can be corrected by using the results of the 

 experiments with different diameter propellers detailed in Chapter X. The w and t data can 

 also be used for assessing the propulsive efficiency to be expected for power plant condi- 

 tions "different from those assumed in the propeller designs used with the series models. 



In addition to estimating the required power for a particular ship design having agreed 

 characteristics, the data are also useful in assessing the penalties which must be paid or the 

 advantages to be gained by changing such characteristics. This is a problem which occurs 

 at some time or other in almost every design study, and this use of the data may well be as 

 important as estimates of actual power. 



XII-1 



