422 



HYDROGRAPHIC MANUAL 



Page 324 



(T) Engineer 



@ Coxswain 



Officer in Charge, 

 left angle and plotting 



@ Right angle man 

 Recorder 

 Fathometer attendant 



O ^ Vor 



Push button for Electric Bell 

 Portable Depth Recorder 



Pivoting fair-lead 

 for sounding wire 



Figure 73. — General plan of a survey launch. 



422. Launch Equipment 



A modern survey launch is equipped with a portable depth recorder, a seuding- 

 and-receiving radiophone, antenna poles, a wire sounding machine, running lights, fire 

 extinguishers, first-aid kit, emergency rations, fresh water breakers, anchors, etc. 

 Other instruments, such as sextants, protractors, compass, clocks, and binoculars, are 

 kept on board the ship when not in use. 



The portable depth recorder is housed in a metal cabinet 21 mches in length by 

 17 inches in width by 10 inches in height, weighing in all 103 pounds. It is operated 

 by electricity supplied by two 6- volt 200-ampere hour storage batteries connected in 

 series. Sound impulses are sent out and the returning echoes are received through 

 units housed in njish submerged over the side of the launch just forward of the mid- 

 ship deck. The fish is usually about 2 feet below the surface of the water. The 

 received echo registers the depth on a facsimile paper with printed scale, producing a 

 continuous profile of the bottom in depths to 160 fathoms while the launch is running 

 at full or reduced speed. Complete details of design and operation are given in 523. 



The radiophone operates from the same batteries as the portable depth recorder. 

 With it the launch party can communicate with the survey ship at distances of at least 

 50 miles and with other launch parties or shore camps at distances up to 20 mUes. 



For vertical casts and bottom samples, soundings are obtained by handlead or wire. 

 The wire sounding machine is power-operated by a jackshaft from the launch engine. 

 The wire is lead aft over a fair-lead attached to the rail. This arrangement is satis- 

 factory when wire soundings are obtained only intermittently and when the launch is 

 completely stopped before the lead is released. However, if soundings are taken regu- 

 larly with wire, a special stanchion is necessary which will ensure keeping the wii'e 

 away from the propeller; or the machine may be installed so that the wire may be led 

 over the side of the launch by the use of a portable boom with fair-lead on the end. 

 (See 4633.) 



