end of the boom- towing assembly and formed a catenary with the first 

 tow boat (see Figure 20). A 300-foot interval was maintained between 

 the two boats and tow speeds of 0.2, 0.6, 0.8, 1.0 and 1.1 knots were 

 established. Swells were 3 to 4 feet in height, and winds were 5 knots 

 from the starboard quarter. 



Measurements were taken of the tensile force developed in the 

 center connector and in both towing cables. A calibrated tension unit 

 (Figure 21) was mounted between the center boom connectors to measure 

 the load at this location. The skirt tended to overturn and plane at 

 a speed over 0.8 knot. At a speed of 1.1 knots the skirt tended to 

 plane at the center of the catenary, and water spilled over the boom. 

 At times the towing assembly tended to submerge during tow. A post-test 

 inspection of the nuts and bolts used to hold the boom to the connectors 

 showed they were galling and had siezed together. 



RESULTS 

 Laboratory Tests 



Figure 22 contains results of the load tests that were conducted 

 on the 6-, 12-, and 18-inch lengths of boom connectors. The load 

 required to separate the connectors is predicted to be 13,500 pounds 

 for the Type I Class 1 connector, 29,000 pounds for the Type I Class 2 

 connector, and 43,000 pounds for the Type II connector. 



In the oil-leakage tests, approximately 0.04 pint per hour leaked 

 through the boom-connector joint when a 0.25-knot current applied tension 

 on the joint. As the tension on the boom connector was reduced to 

 0.01 knot, the leakage through the joint increased to an estimated 

 0.5 pint per hour. 



Field Tests 



The measured straight -line towing loads for different lengths 

 of booms and towing speeds and the theoretical towing loads predicted 

 in Appendix A are shown in Figure 23. The largest load measured was 

 1,450 pounds which was recorded when 1,000 feet of boom was towed at 

 5 knots. 



The average tensile loads in the one towing cable (recorded when 

 1,000 feet of boom was being towed in a catenary configuration at dif- 

 ferent speeds) is shown in Figure 24. The largest tow load, 1922 pounds, 

 was measured when the boom was being towed at 1 knot. Beyond this speed 

 the boom used in the tests turned on its side. Booms that do not turn 

 on their sides at these and higher speeds would place a greater load on 

 the towing cables and connectors. Loads recorded at the center of the 



