Number 6-32NC round-head bolts should be substituted for 

 number 5-44NF bolts. The coarser threads of this bolt will 

 decrease the probability of stripping aluminum screw 

 threads. 



The towing hole of the towing assembly should be lowered 

 2 inches vertically to keep the front of the assembly 

 from submerging when it is towed. 



Polyurethane foam should be placed inside the float of 

 the towing assembly to prevent the assembly from sinking 

 if damage should occur to the float section. 



The female connector of the bulkhead -attachment assembly 

 should be attached to the angle section with 3-inch- 

 length filet welds spaced on 6-inch centers and staggered 

 on opposite sides. This method will prevent the assembly 

 from warping during welding. 



A 3/4-inch shackle should be substituted for the 5/8-inch 

 shackle used in the tests. The larger shackle will give 

 sufficient clearance between a towing cable and the 

 towing assembly. The thickness of the bosses that are 

 welded to the tow hole should be increased from 1/4 inch 

 to 5/16 inch to maintain proper clearance between the 

 shackle and the bosses. 



ACKNOWLEDGMENTS 



Mr. D. J. Graham for developing the overall conceptual designs and 

 sizing the prototype bulkhead attachment and towing assembly. 



Dr. J. J. Der for performing the analysis of boom towing forces 

 (Appendix A) . 



Mr. E. P. Skillman for assisting in the structural analysis of 

 connectors . 



Mr. Kit L. Mack for developing the drawings of Figures 5, 8 and 10. 



Mr. R. C. Towne and Mr. R. A. Bliss for the execution of the 

 laboratory and field tests. 



Mr. C. Quigley and G. S. Duffy for the instrumentation required in 

 the laboratory and field tests. 



Mrs. V. N. Spafford for compiling much of the material in this 

 note and putting it in a readable form. 



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