Principles of naval engineering - Historic Naval Ships Association

CHAPTER 2SHIPDESIGN AND CONSTRUCTIONAs ships have increased in size and complexity,plans for building them have becomemore detailed and more numerous. Today onlymeticulously detailed plans and well conceivedorganization, from the designers to the menworking in the shops and on the ways, can producethe ships required for the Navy.After intensive research, many technical advanceshave been adopted in the design and constructionof warships. These changes werebrought about by the development of weldingtechniques, by the rapid development in aircraft,submarines, and weapons, and by developmentsin electronics and in propulsion plants.This chapter presents information concerningbasic ship design considerations, ship flotation,basic ship structure, ship compartmentation,and the geometry of the ship.BASIC DESIGN CONSIDERATIONSCombat efficiency is the prime requisite ofwarships. Some important factors contributingto combat efficiency are sea-keeping capabilities,maneuverability, and ability to remain inaction after sustaining combat damage.Basic considerations involved in the designof naval ships include the following:1. Cost .— The initial cost is important inwarship design, but it is not the only costconsideration. The cost of maintenance andoperation, as well as the cost and availabilityof the required manning, are equally importantconsiderations.2. Life Expectancy .— The life expectancy ofa ship is limited by ordinary deterioration inservice and also by the possibility of obsolescencedue to the design of more efficient ships.3. Service .— The service to be performedsubstantially affects the design of any ship.4. Port Facilities . — The port facilitiesavailable in the normal operating zone of theship affect the design to some extent. Dockyardfacilities available for drydocking and maintenancework must be taken into consideration.5. Prime Mover .— The type of propellingmachinery to be used must be considered fromthe point of view of the required speed of theship, the location in the ship, space and weightrequirements, and the effect of the machineryon the center of gravity of the ship.6. Special Considerations.— Special considerationssuch as the fuel required, the crew tobe carried, and special weapons are factorswhich restrict the designer of a naval ship.Naval ships are designed for maximum simplicitythat is compatible with the requirementsof service. Naval ships are designed as simplyas possible in order to lower building and operatingcosts and in order to ensure greater availabilityof construction facilities.The following operating considerations affectthe size of a naval ship:1. Width and Length of Canal Locks andDock Facilities . These considerations obviouslyhave an effect on the size of ships that mustuse the canals or dock facilities,2. Effect of Speed . — For large ships, speedmay be maintained with a smaller fraction ofdisplacement devoted to propulsion machinerythan is the case for smaller ships. Also, largeships lose proportionately less speed throughadverse sea conditions.3. Effect of Radius of Action . — An increasingcruising radius may be obtained by increasingdisplacement without increasing thefraction of displacement allotted to fuel andstores. If the fraction of displacement setaside for fuel and stores is increased, someother weight must be decreased. Since the hull15