Time, Speed, and Distance, Continued
Speed x Time
Distance x 60
Example 2. How many minutes (m) are required for a vessel to steam a
distance of 7 nautical miles at a speed of 7.5 knots?
D x 60
7 x 60
T = 56 minutes
The following is an aid to help you
remember these formulas.
Simply place the letters in a triangle, as
shown in figure 8-1. For distance (D),
place your finger over the D and you
have S x T. For speed (S), cover the S
and you have D ÷ T. For time (T), cover
the T and you have
D ÷ S
T, S, and D
Another way of solving problems of distance, speed, and time is by
using the 3-minute rule. The 3-minute rule will help solve mathemat-
ical computations without a nomogram or calculator. The rule states:
The distance traveled in yards over 3 minutes divided by 100 equals the
speed in knots. To simplify, just drop two zeros from any distance
traveled in yard in any 3 minute period.
Example 1: Ship travels 1,600 yd. in 3 min. 1,600/100 = 16 (Speed is 16
Example 2: Ships speed is 16 kn for 3 min. 16 x 100 = 1,600 yd.