2 



Boat Hull Design 



This Chapter is devoted to the structural design of the boat hull. No attempt is made to 

 consider the many and serious problems involved in determining the proper shape of the 

 hull, laying out satisfactory arrangements, ensuring adequate stability, providing sufficient 

 buoyancy in small boats, or estimating power required to obtain a predetermined speed. 



Solutions to the above problems, and others are important and complex. When a sub- 

 stantial investment is involved, either in the building of a large boat or the building of a 

 number of similar small boats, the use of a competent naval architect is highly recommended. 



Structural design is one of the most im- 

 portant parts of the complex problem of boat 

 design. Its purpose is to insure that the 

 structural integrity of the boat is maintained 

 for almost every conceivable loading to which 

 it will be subjected in service. This Chapter 

 should enable anyone familiar with the basic 

 principles of strength of materials, to solve 

 most of the small boat structural design 

 problems. Conservative design is stressed 

 again and again in this manual for a very 

 simple reason: structural failure in service 

 usually involves grave risk to human life. 

 This fact places great responsibility on those 

 involved in determining the scantlings of any 

 boat, large or small. 



In the case of special design problems, 

 as illustrated in Fig. 2-1, the services of a 

 competent structural consultant are required. 



Fig. 2-1. Fiberglass reinforced plastic life- 

 boat, loaded with sandbags, being swung 

 against a pier to test for impact resistance 



(Covrtesy Lane Lifeboat Co.) 



A boat hull is essentially an envelope or shell of predetermined shape. The thickness of 

 this shell and the size and location of whatever supports are provided must be selected to pre- 

 vent the boat from breaking up or losing its shape under the action of the various loads placed 

 on it in service. 



Traditionally, especially in wooden frame and plank construction, the sizes or scantlings 

 of the various components of the boat have been chosen on the basis of years of experience 

 with successful and unsuccessful designs. This experience has been reduced to tables of 



2-1 



