GHA
Well-Known Member
50N & 50S are very different places apparently........
Length of day at high latitudes?
- Thread starter Ladybirdgaffcutter
- Start date
50N & 50S are very different places apparently........
Frank Holden
Well-Known Member
Yes, that's what I was thinking. Sailing on the West Coast, I never really thought of myself being a rufty-tuffty High Latitude sailor.
Ah... but you have the Gulf Stream...... the best we can manage is the Humbolt..
NormanS
Well-Known Member
Yes, and Heaven help us if the Gulf Stream stops or slows.
Skylark
Well-Known Member
That’s really interesting, especially to a novice/recreational ocean sailor.
Other than keeping MP closer to ships 12h00, are there any other practical advantages in changing every 7.5 deg Long / half an hour?
I’d “assumed” that on an average yacht winter Atlantic crossing ships time would be changed by 1 hour increments, say approx every 800M / 5 days / 15 deg Long.
Frank Holden
Well-Known Member
Correcto....faster the ship and higher the latitude more likely you are to shift in one hour steps.... standard issue ship doing 15 knots on a NE/SE/SW/NW course in equatorial waters will probably only flog the clocks 30 minutes once every few days...
On my wee ship in this modern age we don't worry about mer pass... we shift the clocks so that sunset is about 2000.... lets the evening meal be taken in daylight just before change of watch..... cook serves up-eats-goes on watch, 4 to 8 eats - cleans up - goes to bed....
Uricanejack
Well-Known Member
Chronometer always GMT or UTC as official now.
Ship ussualy on standard time for longitude. Or summer time for Port.
Ships time was up to the 2nd Mate.
Most 2nd Mate would ensure noon was in the early afternoon rather than in the morning so he didn’t have to get up to early.
This way, The 3rd Mate would have to stay late or come back for noon.
Any form of rank comes with some privilege
AntarcticPilot
Well-Known Member
Yes, that's what I was thinking. Sailing on the West Coast, I never really thought of myself being a rufty-tuffty High Latitude sailor.
Most places north of 50N or south of 50S are frozen solid - western Europe is an anomaly on a world-wide basis. Most of Canada is SOUTH of the UK, and they have winters that make ours look like summer, and the same goes for Siberia! South Georgia is a glaciated wilderness - and it is at about the same latitude south as Manchester is north. The Falklands, nearer the equator than Cornwall, are a desiccated, chilly desert. Permafrost is normal in most places N or S of 50.
Moving further N and S, MOST places north and south of 60 are permanently covered in glaciers, or at the very least in deep permafrost.
Neil_Y
Well-Known Member
The day length must be the same (although you will be travelling slower as you get close to the poles) but your local noon changes as your longitude changes, nothing to do with latitude.
So the statement is wrong, noon to noon in the same place is 24hrs
Or have I missed something?
So the statement is wrong, noon to noon in the same place is 24hrs
Or have I missed something?
RichardS
N/A
capnsensible
Well-Known Member
That makes sense for me on a yacht. Quite understand the differences necessary for crew and self loading freight on ships though. On an upcoming trip E/W from the Canaries, at this time of year, a 1900 sunset works best for me.
Those were my initial thoughts, before being shown the right path by the more enlightened ones..a very educational thread, thanks for the responses; as often on here, I'm glad I asked the question..
Neil_Y
Well-Known Member
Thanks Richard,
What I meant was the statement (a day noon to noon in these high latitudes is only about 23 1/2 hours)
as it stands is wrong as it suggests it is the latitude which shortens the day and not the movement.
What I meant was the statement (a day noon to noon in these high latitudes is only about 23 1/2 hours)
as it stands is wrong as it suggests it is the latitude which shortens the day and not the movement.
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Mark-1
Well-Known Member
I'm glad you asked the question too. Great question Ladybirdgaffcutter & great answer (within an hour!) anoccasionalyachtsman. Thanks to both.
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Mark-1
Well-Known Member
Thanks Richard,
What I meant was the statement (a day noon to noon in these high latitudes is only about 23 1/2 hours)
as it stands is wrong as it suggests it is the latitude which shortens the day and not the movement.
Yes, but context.
There's an implied "from our perspective sailing west on our ship, a day noon to noon in these high latitudes is only about 23 1/2 hours". It wasn't immediately clear to me either, but once I read post two I find it impossible to read the sentence any other way.
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RichardS
N/A
Thanks Richard,
What I meant was the statement (a day noon to noon in these high latitudes is only about 23 1/2 hours)
as it stands is wrong as it suggests it is the latitude which shortens the day and not the movement.
At the equator 1 degree of longitude is about 70 miles so a slow moving yacht is struggling to make any noticeable difference to the length of the day, whereas at the Poles 1 degree of longitude is around 70 inches so even a slow moving ice yacht is able to turn night into day. Perhaps latitude is, indeed, the main factor .... after movement.
Richard