57 



the best positions of towpoint and elevators. The tests were made under loads 

 imposed by the 100-pound weight towed from the forward towpoint. The combina- 

 tion finally selected as giving the best performance is that shown in Figures 

 28 and 29. 



Following the selection of the best elevator and towpoint positions, 

 systematic towing tests under four loading conditions were carried out. The 

 results of these tests are plotted in Figure 30. Photographs of the float 

 taken during the model-basin tests are shown in Figures 31 through 3^. The 

 action of the float throughout the range of speeds at which tests were made 

 is shown by these photographs. At low speeds, the float operated partly above 

 the water surface under all imposed loads. As the speed was increased, the 

 development of negative pressures produced a downward component of force on 

 the float with ultimate complete submergence. With an increase in the angle 

 of attack due to the increased lift on the elevators at the higher speeds, 

 the float again approached the surface. 



Towing Speed, 2.0 Knots 



Towing Speed, 6.0 Knots 



Figure 31 - Photographs of the TMB 

 48.6-Inch Displacement 

 Float Being Towed 



These tests were made under loads Imposed by 

 the 25-poiind weight towed from the forward 

 towpoint. The float did not become submerged 

 under this set of conditions. 



Towing Speed, 8.0 Knots 



