51
I saw this man in his leisure moments, examining and testing
everything that a vessel needs when at sea.
—Xenophon, Greek historian, 427–355 BCCan you estimate your speed within half a knot at any RPM setting? What three
factors must you know when estimating fuel and provisioning for a cruise? How
do you adjust vital navigation gear to produce top-notch performance?
In Th is Chapter, You’ll Learn How To:
D Solve important navigation calculations in seconds
D Make a super-accurate speed graph for any boat
D Choose, test, and calibrate three vital navigation tools
D Adjust your radar like a pro in fi ve easy steps
Lightning Fast Arrival Time Estimates
How long does it take you to travel 1 nautical mile? Know this and you’ll be able
to quickly estimate your arrival time at waypoints and your favorite anchorages,
even without GPS.
To get the answer, just divide your speed into 60. If your speed is 4 knots,
you’ll travel a mile every 15 minutes. A speed of 5 knots gives a time of 12 minutes
per mile. Averaging 6 knots means you’ll travel a mile in 10 minutes.
Now try these examples:
You are on a powerboat at a speed of 12 knots. How long will it take you to
travel 1 mile?
60 ÷ 12 = 5 minutes
How long will it take you to travel 2 miles?
5 minutes × 2 = 10 minutes
How long will it take you to travel 30 miles?
5 minutes × 30 = 150 minutes, or 2 hours 30 minutes
EASY
CALCULATIONS
AND ADJUSTMENTS
3