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<br />24 <br /> <br />TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS <br /> <br /> <br />ijw. ,~ <br />.J <br />~ <br /> <br />Figure 40.-Sitdown cable car with Canr.eld reel damped <br />to side of car. <br /> <br />are powered by a 430-ampere-hour, 450-pound, <br />12-,'olt battery. <br /> <br />Boot equipment <br />Measurements made from boats require <br />special equipment not used for other types of <br />measurements. <br />Extra large tag-line reels are used on wide <br />streams. Three different tag-line reels are <br />available for boat measurements: <br /> <br />I. A heavy-duty, horizontal-axis reel without <br />a brake and with a capacity of 2,000 feet <br />of %-inch diameter cable. (See fig. 45.) <br />2. A heavy-duty, horizontal-axis reel with a <br />brake and with a capacity of 3,000 feet <br />of %-inch diameter cable. (See fig. 46.) <br />:1. A ,-ertical-axis reel without a brake and with <br />,t capacity of 800 feet of %-inch diameter <br />cable. (See fig. 47.) <br /> <br />A utility line consisting of 30 feet of %.-inch <br />diameter cable with a harness snap at one end <br />and a pelican hook at the other is connected to <br />the free end of the boat tag line and fastened <br />around a tree or post, thereby preventing <br />damage to the tag line. After the tag line is <br />strung across the stream, the reel is usually <br />bolted to a plank and chained to a tree. The tag <br />line is stationed at appropriate intervals. <br />Special equipment is necessary to suspend <br />the meter from the boat when the depths are <br />such that rod suspension cannot be used. <br />A crosspiece reaching across the boat is clamped <br />to the sides of the boat and a boom attached to <br />the center of the crosspiece extends out over <br />the bow. (See fig. 48.) The crosspiece is equippe~ <br />with a guide sheave and clamp arrangement at <br />each end to attach the boat to the tag line and <br />make it possible to slide the boat along the tag <br />line from one station to the next. A small rope <br />can be attached to these clamps so that in an <br />emergency a tug on the rope will release the <br />boat from the tag line. The crosspiece also has <br />a clamp that prevents lateral movement of the <br />boat along the tag line when readings are being <br />made. The boom consists of two structural <br />aluminum channels, one telescoped within the <br />other to permit adjustments in length. The <br />boom is equipped with a reel plate on one end <br />and a sheave over which the meter cable passes <br />on the other. The sheave end of the boom is <br />designed so that by adding a cable clip to the <br />sounding cable, a short distance above the <br />connector, the sheave end of the boom can be <br />retracted when the meter is to be raised out of <br />the water. The raised meter is easy to clean and <br />is in a convenient position when not being <br />operated. <br />All sounding reels fit the boat boom except <br />the A-pack and the Oanfield, which can be <br />made to fit by drilling additional holes in the <br />reel plate on the boom. <br />In addition to the equipment already men- <br />tioned, the following items are needed when <br />making boat measurements: <br />1. A stable boat big enough to support the <br />hydrographers and equipment. <br />2. A motor that can move the boat with ease <br />against the maximum current in the <br />stream. <br />3. A pair of oars for standby use. <br />