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Time, Speed, and Distance, Continued
Distance =
Speed x Time
( minutes)
60
Speed =
Distance x 60
Speed
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?
T(m) =
D x 60
S
T(m) =
7 x 60
7.5
T(m) =
420
T = 56 minutes
7.5
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
Figure 8-1.
D ÷ S
T, S, and D
triangle.
3-Minute Rule
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
knots).
Example 2: Ship’s speed is 16 kn for 3 min. 16 x 100 = 1,600 yd.
8-6
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