Each faired weight was first carefully calibrated by towing it at 

 the end of a line which was adjusted during the test to maintain a constant 

 length from the towpoint on the weight to the water surface throughout the 

 speed range. Towlines of the same length and size were subsequently used in 

 the float tests. Each weight was towed from its two towpoints to obtain a 

 series of loading curves for the float tests. The method of calibrating the 

 weights is illustrated in Figure 6. The towline was led through a pulley at 



Towing Carriage Dynamometer- 



I o o o o o I 



Direction of Motion 



^Faired Weigtit 



Figure 6 - Test Method for Calibration of Faired Weights 



the center of a protractor and secured to the drag dynamometer on the towing 

 carriage. The drag of the weight with its towline and the angle of the tow- 

 line at the surface were measured over a range of speeds for each towpoint. 

 From these measurements, the lift Lq of the weight was computed from the 

 equation 



Lo = D, cot0 [4] 



where D^ is the drag of the weight and its towline and is the angle of the 

 towline with the vertical at the water surface. The results of the calibra- 

 tions are shown in Figures 7 afi<i 8. The drag curves obtained for the faired 



