Page 183 control and signal building 285 



ventioDal barrel buoys, permitting the use of lighter anchor gear. Stainless steel 

 wire rope, %& inch in diameter, composed of 7 strands of 7 wires, has been used satis- 

 factorily for anchor cable. 



The actual buoy has been towed at 10 knots, remaining steady and seaworthy. 

 Anchored by the swivel yoke, with no relieving buoy nor counterweight, in 62 fathoms 

 it has streamed safely m a 4-knot current; it was anchored by a 190-poimd stockless 

 anchor and a 185-fathom anchor cable. Model tests indicate that in a lO-loiot current 

 the anchor cable must be long enough so that it will lead not more than 30° below the 

 horizontal, and in a 6-knot current not more than 45° below the horizontal. 



Cross braces are provided in the buoy to which to secure the radio equipment and 

 batteries. The buoy must be loaded well aft, using ballast if necessray to maintain a 

 trim about 15° down by the stern, and for deep anchorages in strong currents a suf- 

 ficiently long anchor cable must be used. Unless a fixed counterweight is used, the 

 buoy must be anchored by means of the swivel yoke, otherwise the height and weight 

 of the antenna may capsize the buoy. 



Moored by a cable leading horizontally, as to a relieving buoy, the streamlined 

 buoy with fixed counterweight may be used safely in any current likely to be encountered. 



285. Handling Buoys From the Ship 



Buoys are anchored and weighed from the deck of a survey vessel equipped with 

 suitable tackle, booms, and winches to handle the required weights. The essential 

 equipment is: A strong cargo boom that may be rigged so that its end extends beyond 

 the ship's side, a heavy-duty capstan or an anchor winch with drum (niggerhead) 

 powerful enough to hoist the required weight, adequate taclde so arranged that the 

 running faU will pass freely between boom and hoisting equipment, and sufficient 

 deck space under the boom in which to rig and handle buoys. The tackle should be 

 rigged in as simple a manner as possible and arrangement made for changing falls by 

 the use of snatch blocks. This is of special importance in weighing buoys if only one 

 winch is available for hoisting. If a survey ship is not equipped with a cargo boom, 

 buoys may be handled with a boat davit amidships, although generally not with the 

 same facility. On a single-screw vessel a davit on the port side should always be used. 



Buoys are handled best from the port side of a single-screw vessel, because it 

 generally backs to port, turning the bow away from the buoy when it is released. 

 Buoys may be handled from either side of a twin-screw vessel, the engme opposite 

 from the buoy being used in backing away in order to swing the bow away from the 

 buoy. The side of the vessel from which buoys are to be handled must be free from 

 other outboard riggmg which might foul them while they are in the water alongside. 

 The locations of the wire sounding machine and the electric submerged log must be 

 considered. The submerged log should always be drawn inboard when weighing 

 buoys, but this is not necessary when anchoring them provided the log is on the opposite 

 side. Interfering awnings and wind breakers should be removed, in order that the 

 oflacer on the bridge may have an unobstructed view of all operations and be able to 

 maneuver the vessel to the best advantage at all times. The rail and side of the ship 

 under the cargo boom should be protected from possible damage by boards or other 

 fender material, especially when buoys are handled in rough weather. 



In handling buoys, an efficient and experienced deck force is required, so that 

 each member has his several duties to perform, and performs them rapidly and effi- 

 ciently in a cooperative manner to the end that the job will be completed in the least 

 possible time. Each member of the crew should be assigned a succession of duties; 



