-5- 



bridle used for the other models and for one position of tow- 

 point only. For comparative purposes spot tests were made of 

 the TMB design with conventional bridle and of the BuShips design 

 "B" with single cable attachment. A still camera was set up at 

 a fixed position along the basin for taking pictures of the 

 models while under way. 



Part 2 of the program consisted of tests in the model 

 basin to determine the resistance of the targets without cable 

 but with vertical load increments applied to simulate the effect 

 of the weight of various lengths of cable. For this purpose, 

 a special towing bracket was designed which permitted the appli- 

 cation of the simulated cable loads at the towpoint. The model 

 was free to trim and rise and the load increments were applied 

 through counterweights. Several increments were applied at 

 each speed to assure a range that was broad enough to cover 

 any full-scale cable loads anticipated. Resistance, trim, rise, 

 and wetted lengths were determined for each model at a series 

 of initial displacements, initial trims, and positions of tow- 

 point for several speeds ranging up to 35 knots full scale. 

 Additional tests, up to a full-scale speed of 60 knots, with 

 zero cable load, were made with the two boat-type and 

 the TMB design targets. 



Part 3 of the program included tests in the Potomac 

 River off Indian Head, Maryland, to observe the maneuvering 

 characteristics of the models in turns and in waves at various 



