463 HYDROGRAPHIC MANUAL PaGE 388 



forward hoisting bolt. The platform is fastened to both gunwales and extends out- 

 board on one side just enough so that vertical leadline soundings can be taken from it. 

 A framework of 2- by 4-inch lumber is usually built at the outer end of the platform and 

 well braced inboard to the platform itself. Canvas can be placed around the framework 

 to protect the leadsman from spray. 



Should it be inconvenient or impracticable to install a regular sounding chair on a 

 launch or small boat, a canvas belt may serve temporarily to support the leadsman while 

 sounding. A small hinged platform is built and secured to the deck of the launch. A 

 6-inch belt made of canvas is passed around the waist of the leadsman and secured to 

 the launch where convenient, as to pipe frames, stanchions, or handrails. This belt will 

 not only support the leadsman but will also give him enough freedom of action to heave 

 the lead without fear of falling overboard. It does not furnish protection against spray. 



463. Sounding Machines 



A sounding machine is a mechanical device, operated either manually or by power, 

 used to measure, with wire, depths of water too great for the handlead. The apparatus 

 consists of a reel mounted on a stand, with a means for applying power and a brake for 

 stopping the reel. It is used for taking vertical wire soundings, for comparisons with 

 echo soundings, and for obtaining oceanographic data such as bottom specimens, water 

 samples, and temperatures. 



The sounding wire which is wound around the reel, the registering sheave to measure 

 the amount of wire run out and over which the wire passes, and the weight attached 

 to the end of the wire, constitute the depth-measuring equipment. The wire is led over 

 the side or stern of the vessel through a system of sheaves or pulleys, one of which is the 

 registering sheave. 



The operation of taking wire soundings and the speed of operation are described 

 in 3422, and the operation of observing water temperatures is described in 6321. 



4631. Ship Sounding Machines 



The Coast and Geodetic Survey has developed and adopted as standard two types 

 of sounding machines, although many different types, such as the Lucas, Sigsbee, Lietz, 

 Tanner, and Kelvin have been used in the past. The two types are known as the deep- 

 sea machine and the LL-type machine; they are basically the same in construction and 

 operation, differing principally in size of reel. Their speed, smoothness, and ease of 

 operation are believed to be superior to those of other types. Piano wire is usually used 

 on the deep-sea machine and stranded wire on the LL-type machine, although either 

 kind of wire can be used on either machine. Drawings and specifications of the 

 machines can be obtained from the Washington Office when needed. 



The basic description of both types of machines is as follows: A reel is mounted so 

 as to turn freely on a control shaft which has a collar by means of which the reel can be 

 slid from one side to the other by a handle. On one side of the reel a brake disk is 

 secured to the frame of the machine and on the other side of the reel a clutch disk is 

 attached to a shaft to which is also attached the power pulley or gear. The brake and 

 clutch disks are beveled and covered with a preformed Raybestos brake lining. The 

 control shaft has a worm screw cut in one end which causes it to shift in and out longi- 

 tudinally when the end of the operating handle is moved from side to side. 



When the machines are electric-driven a 3 horsepower, watertight Diehl electric 

 motor is used; the motor is ball-bearing, compound-wound, interpole, variable speed 



