285 HYDROGRAPHIC MANUAL Page 184 



and after each is completed, he should, on his own initiative, obtain the implement or 

 material required next and stand by ready to perform his next duty at the required 

 time. The officer on the bridge should watch every detail of the operation, to see 

 that it is correctly executed, and so that he can assist by maneuvering the vessel cor- 

 rectly at the proper time. Shouted instructions between the bridge and the deck, 

 which risk being misunderstood, should be unnecessary. The required maneuvers 

 should be anticipated and tlie officer on the bridge should always have the ship in the 

 proper position to facilitate the operations. 



Twin-screw vessels are generally easier to maneuver into position than single- 

 screw vessels. The heading can be more easily maintained and the direction of the 

 heading may be changed without changing the ship's position appreciably by working 

 the engines against each other. Maneuvers must be made with greater caution and 

 at a slower speed with a single-screw vessel. 



Regardless of the type of vessel, buoys are anchored with the wind or current 

 acting against the side of the ship from which the buoy is to be released. The wind 

 should preferabh^ be about four points on the bow so that the ship will drift away 

 from the buoy when it is placed in the water. The ship should always have a little 

 sternway when the buoy is released; never under any circumstances, headway, if the 

 buoys are handled from the bow. As the ship moves slowly astern the anchor cable 

 is payed out until it is all clear, when the anchor is released. The ship should have 

 sufficient sternway to clear the position, for the buoy is towed toward the anchor as the 

 latter sinks to the bottom. 



The maneuvers required to go alongside a buoy to weigh it or change the buoy 

 structure are more difficult. The ship should be maneuvered to a position on the 

 downstream or lee side of the buoy. This may be determined by the direction between 

 the buoy and its relieving barrel or, if no relieving barrel is used, by the rope hoisting 

 sling which is always located on the opposite side from the anchor cable. When the 

 ship is in the appropriate position it should be headed into the current, directly for the 

 buoy, and the speed reduced. The approach should be painfully slow in order not to 

 overrun the buoy, but steerageway must be maintained. The approximate speed of 

 the ship may be judged by the ripple marks, bubbles, or small pieces of floating matter 

 on the siu-face of the water as they are passed. The last hundred meters should be 

 traversed with the engines stopped, so that they may be reversed momentarily when 

 the buoy is on the bow and the ship will be almost stationary when the buoy is directly 

 beneath the cargo boom, and can be maintained in that position until the buoy is 

 hooked. It should never be necessary to give the ship sternway as this is likely to 

 turn the bow too far away from the buoy. If the buoy can be hooked quickly enough, 

 a very little headway is advantageous to avoid putting a strain on the anchor cable, 

 since the anchor is still ahead of the ship. This requires delicate maneuvering, and 

 considerable experience is necessary before buoys can be regularly weighed expeditiously 

 with a single-screw vessel without damaging them. 



In general, the necessary maneuvers are more easily made in moderate currents 

 and moderate winds, because steerageway can be mamtained with little or no head- 

 way. Surprisingly enough a calm sea with no current nor wind is not a particular 

 advantage in weighing buoys, especially with a single-screw vessel. The following are 



