Ch. 20] 



ACCESSORY EQUIPMENT 



355 



a well in the center through which the sound-wave projector operates. 

 Three outboard motors are used, two of 16 horsepower each and one of 

 10 horsepower. 



The echo-sounding equipment includes the sounding recorder, pro- 

 jector, storage batteries, and depth-checking bar. The projector is of 

 the outboard type which is designed to be operated by being swung over 



Sounding boat on reservoir survey. The man in the bow maintains shore 



contact with a hand radio, the man with the flag operates the echo-sounding 

 recorder, the man standing operates a device that measures distance from shore 

 by a taut piano wire, and the man in the stern operates the outboard motor that 



powers the boat. 



the side of the boat and positioned below the water line for observa- 

 tions. However, with a boat of the size used for purposes of mobility, 

 it has been found desirable, from the standpoint of the most satisfac- 

 tory and safest loading of the boat, to operate the projector from a well 

 centered in the hull. A simple lowering device positions the projector 

 at the operating depth of 1 foot below the water surface. The heavy 

 storage batteries, weighing about 165 pounds, are charged in place on 

 the boat by a small motor generator. 



One of the chief pieces of equipment is the circumferential-type dis- 

 tance-measuring wheel devised by TVA's Chief Hydrographer, E. H. 

 McCain. The distance-measuring apparatus consists of the drum of a 

 Ford automobile wheel on which is wound 2,500 feet of piano wire 0.039 

 inch in diameter. The wire leads from the drum over two sheaves to a 



