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what are nautical miles? i thought we were talking about knots.

Nautical miles are distance
Knots are speed

Oh, okay, thanks for clearing that up for me! I feel smarter already!

Catigale wrote:When you gently correct pretentious sailors who insist that sailers only use nautical miles, remind them that Chapmans states differently.

Nautical miles offshore
Statute miles inland, lakes, coastal waters

Well then ... call me a pretentious sailor - because (as a CYA certified advanced coastal navigator, and celestial navigator) I think that when on the water, one should refer to; distance in "nautical miles", and speed in "knots".

FYI: A nautical mile is based on the circumference of the earth, and is equal to one minute of latitude arc, or 1/60 of a degree, which is why this particular system of measurement is used for charting and navigating. also see: http://www.onlineconversion.com/faq_07.htm

I have Chapmans, I think their goal in saying to use statute miles when on inland lakes and coastal waters is probably:
a) because the small difference between nautical and statute (1 nautical = 1.15 statute) matters less for shorter distances than it would on longer offshore distance.
b) as a safety precaution directed more at small lake skippers in go-fast runabouts, so they have a better perception of speed using a land measurement system they are familiar with.

To me, the reasons to use nautical terms on the water are simple:

1) nautical chart distances are in nautical miles, so calculating distance/speed/time can easily be calculated using knots as speed and nautical miles as distance. Calculation formula of; (60xD=SxT). (where; D=distance, S=speed, and T=time)
Example:
Q: your chart says you have 15 nautical miles left to get to the marina, how long will it will take you if you are going 10 "knots" per/hour?
A: easy, one hour and 30 minutes.
- How long will it take if you are going 10 "miles" per/hour ??
(yes, I realize you can set "digital" chart plotters to statute or metric as well)

2) some people may have a better "feel" for how fast they are going, or how far a distance is by using more familiar land measurement system, but I think it is more practical as a sailor/boater to learn and understand the nautical terms and systems and their benefits.

3) mixing measurement & speed systems (nautical distance against statute or metric speed) is asking for data errors and complicating calculations.

4) common language. Nautical speed and distance is the same around the world to all boaters. (verses: Metric/Statute) So if a metric Canadian sailor is on the dock talking to a statute American sailor, they can both speak the same nautical language

... but that's just me

Okay, I don't feel so smart anymore.

I think Chapmans is being informative as to what is common practice, and don't get into the " best practice" fight.

They are correct ( or at least fit my experience) that statute miles are used extensively inland and coastal, at least where I sail.

My paper charts are scaled in both units, obviously electronic charts are too.

I think Mariners should understand both systems and where they might run into them, especially if you sail coastal where you are likely to hear both.

One is not more "sophisticated" than the other although I think people try that game out a lot in yacht clubs.

BOAT wrote:what are nautical miles? i thought we were talking about knots.

I think u got Ur Knots in a Binder !!


J

Another piece of trivia: the "knot" denomination comes from the good old days when sailors measured the speed of the boat by way of a "log" (a contraption made of weighed wooden structure meant to stay put in the ship's wake, at the end of a rope). The first mate would throw the log overboard. The rope was marked with knots--literally--every 8 fathoms (a fathom is about an average guy's height) Then he would flip an hourglass over and measure half a minute--how many knots passed through his fingers? Well, that was the ship's speed. Knots per hour.
It so happens that the marine mile also corresponds roughly to one minute of a meridian arch (60'th part) which made map measuring even more convenient.
The word "mile" actually comes from Latin--stands for "millia passum" (one thousand paces) cuz the Romans used a double step (left and right) for one "pace". That woulld make a land mile about 1.6 or 1.7 hundred meters. Shorter than the marine mile.
Go figure

Well, my boat has been in the shop for five weeks and the shop owner called me today. He said that he has put 20 + hours into the repair of the hatch and he just can't get it to fit up properly.

Bill at Boats 4 Sail, do you still have that 26X sliding hatch?

Anyone else out there have one for sale? If you don't have it Bill, and no one else does either, is there anyone in Colorado who would loan their hatch to a shop for a couple of days so a mold or copy can be made?
Thanks! Jon Allen