4632 



HYDROGRAPHIC MANUAL 



Page 390 



but this is not used for depth measurements on account of the varying circumferences of 

 different amounts of wu-e on the reel. The registering sheave is usually mounted above 

 the machine. 



Such machines have been used only intermittently in recent years since the adop- 

 tion of echo sounding, but their successful operation is evidenced by 6 weeks of con- 

 tinuous deep-sea sounding by one ship in 1923, in depths to 4,600 fathoms, without 

 loss of any wire or equipment. 



The LL-type of sounding machine is used on practically all survey ships and all 

 auxiliary vessels where a power-driven machine is needed. The reel has a mean 

 circumference of about )2 fathom and will hold about 900 fathoms of stranded wire or 

 about 2,700 fathoms of piano whe. The reel is usually made of bronze. When used 

 on survej^ ships it is almost invariably electric-powered, but it may be powered by a 

 steam motor, like the Dake motor, or by a stationary gasoline engine, or driven from 

 the gasoline engine of a launch (see 4633). The weight of this machine complete, with 

 bronze reel, electric motor, frame, base, etc., is about 975 pounds; without motor and 

 power transmission its weight is about 175 pounds. The L-type of sounding machine 

 is an older model of the LL-type, differing from it only in minor details. 



This same machine is used on launches where a power-driven sounding machine is 

 needed, although many other types have been used in the past. 



An automatic brake sounding machine has also been developed by the Coast and 

 Geodetic Survey. Its prmcipal characteristic is that the brake is automaticall}^ 

 applied by means of a series of triggers and springs the instant the wire slacks when the 

 lead strikes bottom, but it requires a fine adjustment to ensure against the brake being 

 applied at other times. Its cost is much higher than that of the LL-type. 



Figure 81. — Hand sounding machine. 



4632. Hand Sounding Machine 



The hand sounding machine most extensively used by 

 the Coast and Geodetic Survey is similar to those used on 

 commercial vessels and is illustrated in figure 81. It has 

 a bronze reel and brass standards. The brake is a wood- 

 lined clamp, either forced against the reel, or released, by 

 a small handle above the reel. The handles are so hinged 

 that they can be disengaged from the shaft while the 

 wire runs out and engaged for reeling in. The machine 

 is mounted on a wooden base provided with clamps. 

 Its box may be used as a cover for the machine, or as a 

 support for it when in use. 



The machine is used for depths from 10 to 150 fathoms. 

 It is usually mounted on the stern of a ship's launch, with 

 a sheave overhanging far enough to keep the wire well 

 clear of the stern and the propeller. Where many wire 

 soundings are to be taken a power machine should be 

 requisitioned and installed. 



4633. Installation of Sounding Machines 



A ship sounding machine is usually installed on or near the bridge with the wire 

 leading outboard over the side, where the officer-in-charge can supervise the operation 



