3. Sufficient rigidity to resist the bending and buckling loads 

 and yet be able to maintain vertical attitude, 



4. Provision for proper towing load distribution over the vertical 

 boom end . 



Because boom-bulkhead attachments would be used primarily in 

 confined harbor situations, the attachments were to have the following 

 operational characteristics: 



1. Easy adjustment to variations in water depth caused by tides. 



2. Rotational flexibility about the track axis to minimize loads 

 caused by bidirectional currents. 



3. Bulkhead fitting to provide an oil-tight seal. 



DESIGNS STUDIED 



The structural requirements of the proposed designs, relating the 

 size of components to the given materials, are analyzed in Appendix B. 

 The design finally selected for development evolved from the information 

 found in Appendix A and B and the findings from the study of the various 

 hardware designs, as discussed below. 



Boom Connector 



Those designs considered in the CEL study for a universal boom 

 connector to couple booms of different types and sizes* are shown in 

 cross section in Figure 1. In each case, the boom end is clamped to the 

 connector by means of a metal plate and bolts. All candidates have 

 mounting holes for attachment of the primary tension member of a par- 

 ticular boom vendor. The boom end has a rod (flexible or rigid) running 

 the full height of the boom to assist in keeping the connector attached 

 to the boom under tensile loads. Each of the candidate designs shown 

 have certain advantages and disadvantages which are tabulated in Table 1. 



Towing Assembly 



The two primary objectives of a separate towing assembly are the 

 control of the towing load distribution over the boom height (depending 

 upon the location of the primary tension member) and maintenance of the 



* 12-inch (Type I, Class 1), 24-inch (Type I, Class 2), and 36-inch 

 (Type II). 



