Nautical Miles and Knots on a Cruise
The units on every chart and every captain’s announcement.
Get a Free Cruise QuoteNautical Miles on a Cruise, Explained
Captains, charts and itinerary distances all speak in nautical miles, so a little fluency helps. Here is what a nautical mile is, where the knot came from, and how to turn the nautical miles in a cruise announcement into something you can picture.
The Nautical Mile in One Paragraph
According to NOAA Ocean Service, a nautical mile is based on the globe’s grid of latitude and longitude: one nautical mile equals one minute of latitude. It is slightly longer than a land mile, at about 1.1508 statute miles. The international nautical mile was fixed at exactly 1.852 kilometers in 1929 by the body now called the International Hydrographic Organization; the United States adopted that standard in 1954 and the United Kingdom in 1970.
| Unit | Equals |
|---|---|
| 1 nautical mile | 1.852 km (exact), about 1.1508 statute miles, about 6,076 feet |
| 1 statute mile | About 0.869 nautical miles, about 1.609 km |
| 1 knot | 1 nautical mile per hour, about 1.15 mph, 1.852 km/h |
| 1 degree of latitude | 60 nautical miles |
Where the Knot Came From
In the 17th century, sailors measured speed with a “common log”: a wooden float on a line knotted at regular intervals. They let it drift astern for a set time, often measured with a sandglass, and counted how many knots ran out. The count became the ship’s speed, and the name stuck. Modern ships use satellite positioning and speed logs, but the unit is the same.
Reading the Captain’s Noon Report
Many ships give a midday update from the bridge with the position, the speed and the distance to the next port. Now you can decode it. If the ship is 240 nautical miles from the next port at 12 knots, that is 20 hours of sailing — which is why arrival is set for the next morning. At 20 knots, the same distance would take 12 hours. Our ocean miles calculator does these sums for you.
Why Sea Distances Look Short
A distance in nautical miles sounds smaller than the same distance in land miles, because each nautical mile is about 15 percent longer. Multiply by 1.15 for statute miles or by 1.852 for kilometers. And remember that a ship follows a planned route around headlands and through channels, so the sailing distance is often longer than a straight line on a map.
Nautical Mile Questions
How long is a nautical mile?
Exactly 1,852 meters, about 1.15 statute miles or 6,076 feet. It was originally based on one minute of latitude.
Is a knot the same as a nautical mile?
No. A nautical mile is a distance; a knot is a speed of one nautical mile per hour. Saying “knots per hour” is a common mistake.
Let Us Read the Miles for You
Our cruise advisors at Mister Cruise check the distances and timings on every itinerary they quote, so you know which days are long at sea. Free.
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