""Used both at sea and in the air, a knot is nothing more than a mile per hour. Eight knots means 8 miles per hour. Except they are nautical miles, not statute miles. The nautical kind are slightly longer, at 6,082 feet versus the statute mile’s 5,280. Thus, 8 knots in an airplane is slightly faster than 8 miles per hour in a car. To be precise, multiply by 1.15. (Incidentally, the homonymic between “knot” and “nautical” is, well, not the right idea. The original definition of “knot” goes back to when lengths of knotted rope were tossed from a ship to figure distances. Eventually these literal knots were equated with nautical miles.)"”

Is this true? Sounds kind of improbable…

CV

It’s true, as a check of the American Heritage Dictionary will reveal.

Here’s an explanation of the Logline.

Welcome to Wordorigins!

edit to add welcome.

Also note that for a lot of English speakers (like me), the syllable ‘naut’ is not homophonous with ‘knot’.

Clear explanation in your link, happydog.
But why 47 feet 3 inches between knots on the line? And why 28 seconds on the timer? When (and to what extent) were these measurements standardized?

From Happydog’s link:

The distance of 47 feet 3 inches as a fraction of 1 nautical mile (i.e. 6,080 feet) is directly relative to 28 seconds as a fraction of 1 hour in seconds (3,600 seconds).

Both have a ratio of 0.0077.

Other ratios and measures could have been chosen, but I suppose these were about right for practical purposes and were decided by trial and error. 47.3 feet was short enough to give a result in a short period of time, but long enough that the count did not happen too quickly. 28 seconds was short enough to allow for the quick taking of the measurement when needed, but long enough to get a meaningful result.

As for standardization, I suspect that in the early days of sailing there was little standardization. But by the 19th century, it would have been pretty well standardized. Navigational references would have been produced with these measurements in mind.

Perhaps the odd number of seconds is a relic of standardisation of the nautical mile - was there an older nautical mile that was longer?

The nautical mile is the distance spanned by one minute of the arc of latitude at the Earths surface.  The Britsh define this as 1853.18 meters (6082 feet), while international standards define it as 1852 meters.  So no really significantly different older version!

However with all this global warming the sea water will expand and the Nautical mile will have to be longer… ;-)

Should have checked under “knot” in the OED, not “nautical mile”.  For “knot” we get these references:

1669 STURMY Mariner’s Mag. IV. 146 The distance between every one of the Knots must be 50 Foot; as many of these as run out in half a Minute, so many Miles or Minutes the Ship saileth in an Hour. 1760-72 tr. Juan & Ulloa’s Voy. (ed. 3) I. 9 The distance between the knots on the log-line should contain 1/120 of a mile, supposing the glass to run exactly half a minute.

The correct distance apart for the knots for a thirty-second hour glass is 50ft 8ins (1/120 mile) as per the second quote. None of this, however, explains the change to 47ft 3ins and 28 seconds.

It was surprising to see the technically incorrect expression “knots per hour” dating as far back as the mid C18th and by people “who should know better” like Captain Cook.  I have in my possession an letter describing of the escape of HMS Calliope from Apia harbour written shortly after the event in 1889, where the writer, the Navigating Officer, uses the expression “knots per hour”, too.

Incidentally, if you’re traveling at 8 knots in an airplane, you’re either on the ground or soon to be headed that way.