4 ms·
Not mentioning that the nautical mile is essentially 1 minute of arc on any meridian, which is the key fact. Once you have the distance of nautical mile, then
by rdl 13y ago
Not mentioning that the nautical mile is essentially 1 minute of arc on any meridian, which is the key fact. Once you have the distance of nautical mile, then it's reasonable to measure your speed with respect to something fixed relative to the water around you.
("Why is a nautical mile 1 MOA and a statute mile something else" is the more interesting question, IMO)
- Patrick_Devine 13y agoOR stated another way... "the average length of one minute of one degree of arc on a great circle".
- mjlee 13y agoThis article seems to answer "Why is it called a knot?" instead. You're correct that the nautical mile is one minute of arc across a great circle and as such is a meaningful unit to a navigator.
- mikeash 13y agoI can't read the article, so forgive anything that's off base here.... Omitting that seems ludicrous. Without that, you're really answering the question, "why are they called 'knots'". Which is interesting, but completely different from the question of why you use knots.
- dfc 13y agohttp://web.archive.org/web/20140409162921/https://alum.mit.edu/pages/sliceofmit/2014/04/09/why-is-speed-at-sea-measured-in-knots/ http://web.archive.org/web/20140409162921/https://alum.mit.e...
- kephra 13y ago> Why is a nautical mile 1 MOA and a statute mile something else" is the more interesting question, IMO Lets handwave a conspiracy theory: The Sumerian Ku was 518.5mm. A SAR-kus (60*60 kus) 1866meter is nearly same as a sea mile by 0.7%. One ku per second equals one sea mile per hour, equals one knot. So ancients did already know the size of earth by one and a half digits in 60er system (1/120). This required a mathemagical wisdom, like knowing how to compute square roots and pi to several 60system digits behind the comma, that was lost after 333bc. Weights and measurements got mostly smaller and seldom bigger over time. The Sumerian mine lost 10% to become the lbs. Kings did declare the weights and length measurements at their time. Make the rod a bit shorter, if you have to hand out parcels after an invasion, and you have a good loot left for yourself. Use the bigger weights, after asking for ransom of a city, and even throw your sword into the balance, with the words VAE VICTIS! But making the weights bigger was a seldom exception. More common was the gain in declaring them smaller.