TEST PROCEDURE 



To measure the resistance, the buoy to be tested was fastened to 

 the end of a towing strut which was submerged to a depth of 34 5/8 inches. 

 The other end of the strut was clamped to the towing beam of the drag dyna- 

 mometer of the towing carriage, as is shown in Figure 11. The strut was a 

 standard towing strut for submerged bodies (2) of ogival section with a chord 

 length of 4 inches and a thickness of 1 inch. 



The l/3-scale model of Buoy 1 was tested at speeds between 0.20 and 

 13 knots for various positions of the pin simulating the mooring line. 



The l/3-scale models of Buoys 2 and 3 were tested with and without 

 the towing bails at speeds from 1 to 9 knots. The towing bails were mounted 

 on the models 45 degrees below the horizontal axis of the buoy. 



The full-scale model of Buoy 1 was tested for drag at speeds from 

 0.50 to 3.50 knots. The model was also tested for towing stability by towing 

 a 200-pound weight from the towing carriage 18 feet below the water surface, 

 with the mooring line from the buoy fastened to the weight. The mooring line 

 was short enough so that the buoy would tow submerged. A sketch of this ar- 

 rangement is shown in Figure 12. 



To obtain the net drag of the buoys it was necessary to determine 

 the tare drag of the supporting strut. This was done in two ways. The drag 

 of the strut was first measured alone and then in the wake of the buoy in 

 question. On both tests the strut was clamped to the towing beam of the drag 

 dynamometer of the towing carriage, but in the latter test the buoy, support- 

 ed independently of the towing strut by means of a U-frame, was maintained as 

 close as possible to its original position relative to the strut without ac- 

 tually touching it; see Figure 13. 



The tests of the l/3-scale models of Buoys 1 and 2 were limited to 

 a maximum speed of 13 knots. The towing speed of Buoy 3 was limited to 9 

 knots because of excessive vibrations above that speed. 



