Ship’s Characteristics, Continued

Ship’s Characteristics, Continued Acceleration and Deceleration Tables From the deceleration table, it is determined that 1 minute is required to decelerate from 15 knots to 10 knots. Because the rate of deceleration is always constant between any two speeds, the average of these two speeds is the average speed of the ship during this time period. By computation, 15 knots plus 10 knots gives an average speed, during 1 minute of deceleration, of 12 l/2 knots. Determination of average speed is the crux of this problem. To compute the distance the ship will travel in 1 minute at 12 l/2 knots, multiply 2,000 (yards) by 12.5 (knots) and divide by 60 (minutes). The result is approximately 417 (yards). Measure back 417 yards along the DR track from a point abeam the dredge. This latter point is where it is recommended that turns for 10 knots be rung up on the engines. Example 2: A ship is proceeding through Ambrose channel at 10 knots. The navigator is informed that 25 knots is L be ordered when the ship clears the channel. One computation is requested by the OOD: How far along the DR track will the ship travel from the time 25 knots is rung up until she is making that speed? Because the ship is proceeding at only 10 knots, a running tabulation of speeds and times must be considered. Going to the acceleration part of the table, compute the distance traveled in three steps: 10 to 15, 15 to 20, and Table 11-2. Sample Acceleration 20 to 25. and Deceleration Table 11-10