Ship’s Characteristics, Continued

Ship’s Characteristics, Continued Discussion When the rudder is put over in making a turn, the stem is forced away from the direction of the turn. Because of momentum, the ship turns very slowly from her original course for several lengths. She then commences to gain ground in the new direction, moving sideways through the water to a considerable degree. This naturally results in loss of speed and is why, when a column turn is made, a vessel gains rapidly on the ship ahead while that ship is turning, but loses this distance during her own turn when the first ship completes her turn and steadies on the new course. Each ship should have available on the bridge a folder of the ship’s tactical characteristics. It should be carefully studied by all shiphandlers. Pertinent data should also be available at other stations concerned with ship maneuvers, such as the combat information center (CIC). These tables are drawn up with the ship making several turning runs at different speeds and using various rudder angles. Table 11-1 is a sample advance and transfer table for a ship Figure 11-5. Turning circle. making a turn at 15 knots, using standard rudder. Similar tables are compiled for other rudder angles at the same and different speeds. The time required to make the various turns may also be shown. Acceleration At times, allowance must be made for the rate at which a ship increases and and decreases speed. Another part of the tactical data folder, therefore, Deceleration is the acceleration/deceleration table, of which a sample is given in table Tables 11-2. Practical examples of it’s use follow. Example 1: A ship is standing up a channel at 15 knots. The captain desires to maintain speed as long as possible, but must pass an anchored dredge at a maximum speed of 10 knots. Determine how far before reaching the dredge a speed reduction should be commenced. 11-9