BULKHEAD ATTACHMENT 



The bulkhead attachment candidates were analyzed structurally 

 for their ability to withstand the tensile and bending loads indicated 

 in Figures 3 and 4. 



Referring to Figure 3, if the dimensions for the split tube sliding 

 track are the same as for the first boom connector candidate discussed 

 in this Appendix, the assembly can safely carry the full Type II boom 

 tensile tow load appearing in Table A-1. Using a free-body diagram 

 similar to that employed for the boom connector calculations, it can 

 be determined that the point of maximum stress in the assembly of Fig- 

 ure 3 when subjected to bending loads occurs at the outer diameter 

 of the sliding track near the support angle. To maintain the design 

 safety factor of 3.5, this maximum stress must be held to 10^ psi. 

 The maximum allowable bending load, directed perpendicular to the ten- 

 sile load shown in Figure 3, is calculated to be 1,740 pounds, which 

 should be sufficient because the bulkhead attachment will be used in 

 harbor situations where the currents and boom lengths are relatively 

 low. It should be noted that from Table A-1 for 1,000 feet of Type I 

 Class 1 boom (which is the type most likely to be used with the bulkhead 

 attachment) the towline force is 1,250 pounds, or almost 500 pounds less 

 than necessary for a design safety factor of 3.5. 



The design candidate of Figure 4 was studied in the same manner 

 as described above. It was found that under a pure tensile load of 

 13,600 pounds (see Table A-1) a plate thickness of 0.019 inch was 

 required for the roller assembly. As in the design candidate of Figure 

 3, the more strict structural requirements were derived from the bending 

 loads the assembly would experience with fluctuating tidal currents. 

 If the plate thickness of the roller assembly is 0.25 inch, the maximum 

 allowable bending load is calculated to be 1,500 pounds, similar to 

 the allowable design load for the candidate of Figure 3. The roller 

 track is quite rigid, and mil support the full 13,600-pound bending 

 load with a flange 0.25 inch thick by 2 inches wide. 



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