PART 4 



Hydrodynamics Applied to the Design of a Ship 



CHAPTER 63 



Basic Factors in Ship Design 



63.1 Definition of Ship Design 442 



63 . 2 Application and Scope of Part 4 442 63 . 5 



63 . 3 General Assumptions as to Propelling Machin- 63 . 6 



ery 443 63.7 



63.4 The Fundamental Requirements for Every 63.8 



Ship 443 



Design as a Compromise 444 



The Essence of Design 444 



The Design Schedule for a Ship 444 



The Field for Future Improvements in Design 444 



63.1 Definition of Ship Design. One who 

 fashions a ship in this modern age of specialization 

 can not be satisfied simply that it floats, moves 

 itself through the water, and carries passengers 

 or cargo over the water from one place to another. 

 It must meet certain definite requirements; 

 indeed, it must almost certainly do some things 

 better than any other ship which can be built to 

 meet those requirements. This superiority can be 

 developed in the evolution of the design, in the 

 use of the most suitable materials, or in the 

 application of the best workmanship throughout. 

 It can be developed by a combination of all three, 

 but it is in the evolution of the design in general, 

 and the hydrodynamic design in particular, that 

 we are concerned here. 



Design, for the naval architect and marine 

 engineer, may be defined as the art of fashioning 

 a ship by an intelligent and logical selection of 

 those features of form, size, proportions, and 

 arrangement which are open to his choice, in 

 combination with those features which are 

 imposed upon him by circumstances beyond his 

 control. 



Design is largely a matter of thinking and 

 planning. This requires, above all, knowledge, 

 intelligence, and understanding. One can have 

 any one or two of these quaUties, but without the 

 third his ship-designing ability lacks that some- 

 thing which will make his designs uniformly 

 successful. Knowledge can be gained from books 

 and many other sources of engineering informa- 



tion. Intelligence may be brought out by a process 

 of uncovering that which is innate in any architect 

 and engineer. Understanding must be learned, 

 and often the hard way. 



Understanding, in general, means a compre- 

 hension of all problems and relationships and 

 phenomena. Specifically, to the one deahng with 

 problems of hydrodynamics, it means compre- 

 hension in its fullest sense of the elements and 

 the intricacies of liquid flow, and of the means of 

 dealing with and predicting the characteristics of 

 this flow. 



63.2 Application and Scope of Part 4. It is 

 hoped that a study as well as a reading of the 

 first three parts of the book has given the ship 

 designer a generous share of the knowledge, 

 intelligence, and understanding needed to fashion 

 the form and features of a complicated modern 

 ship. As his knowledge increases, so will his 

 intelligence and his understanding. He will 

 realize that he can grasp the meaning of those 

 manifestations of nature that may long have 

 remained a mystery to him, and that he can 

 comprehend the whys and wherefores of so many 

 kinds of flow and action phenomena that were 

 formerly bewildering and meaningless. 



This fourth part of the book therefore under- 

 takes to outhne the procedure whereby the in- 

 formation set down in Parts 1, 2, and 3 may be 

 utihzed in the hydrodynamic aspects of ship 

 design. After taking up various phases of the 

 procedure, in a manner paralleling those followed 



442 



