time zones

[Poly]

Originally Posted by neilda

Never heard of UTC before,

UTC = GMT same thing, different name.

I thought the PC version would pick up the time change from the internal clock.

yeah but mariners are funny folk who like to work in GMT rather than local time, except when it suits them!

[PeterM]

I was 24 hours out ! Whats 'Zulu' time then - whats DST , GMT & BST compared to UTC ?

Can I have whole new thread for this ?

[willk]

Originally Posted by Blackroady

Can I have whole new thread for this ?

It seems that you can (I get them all the time!)

We use ADT in the club - Adjusted Divers Time.....

Which is about 25% later than would be generally acceptable under the given circumstances

[PeterM]

So I reckon ;

GMT - Greenwich mean time
BST - British summer time ( GMT + 1)
ZULU - same as GMT ?
UTC - SAME AS GMT/ZULU ?

Any others out there for UK time ?

Europe is CET ( BST + 1 ) ?

[Poly]

Originally Posted by Blackroady

I was 24 hours out ! Whats 'Zulu' time then - whats DST , GMT & BST compared to UTC ?

UTC = Coordinated Universal Time
GMT = Greenwich Mean Time
Z = Zulu time

all are the same thing in terms of "time zone". I think there are some very subtle distinctions relating to how we "measure" time, but to you and me - its the time in London during "winter".

DST = Daylight Saving Time
BST = British Summer Time

DST is the concept that during some months of the year we manually shift the time zone to better suit our "working lifes" and supposedly to reduce the number of road accidents.

BST is local time in London during the "summer", it is used in the UK as the convention for DST. Different time zones use different DST's - most add an hour, but the start and end dates are different in different countries.

BST = UTC+1 e.g. 0900 BST = 0800 UTC

the military abbreviated time zones to single letters - and defined UTC/GMT as Z.

Can I have whole new thread for this ?

done

[Poly]

Originally Posted by Blackroady

Europe is CET ( BST + 1 ) ?

CET = GMT+1

But at the same time as we switch to BST the rest of the EU switches to CEST which is GMT+2

[SPR]

For people trouble sleeping!

http://en.wikipedia.org/wiki/Coordinated_Universal_Time

S.

[Avocet]

I'm not entirely sure what you want from this thread.

But bear with me on this one....

Rightly or wrongly we (ie British Isles) run a system whereby we use UCT (Temps Universel Coordonné) which is GMT (Greenwich Mean Time) (apart from fractions of a second not exceeding 0.9 of one) but we change (rightly or wrongly) to BST (British Summer Time) for the summer months. The dates on which the times change vary slightly from year to year. This year our (British) clocks went forward (one SPRINGS forward) in spring on eve of 28 March. GMT (UCT) (if you are following this) starts again on 25 October (when one FALLS back: Fall being our American cousins' word for Autumn).

Most computers recognise this but when reading tide times you need to know which time is being shown: BST (as we currently are) needs an hour added to UCT (in which most tide times are given).

Oh. And by the way you may need to know that: the Earth's rotational speed is very slowly decreasing due to tidal deceleration, causing the mean solar day to increase in length.

This may or may not be a good thing but it messes all the above about.

And if anyone is still reading this: 'Zulu time' = UTC = CET = Central European Time.

I think I'm heading to the bilges: and I've got my bets on which moderator is going to put me there....

[Nos4r2]

Won't be me...This is all very relevant IMO.

[Avocet]

I wasn't anticipating you, and Louise has been very quiet recently.

Scurvey Crew and I are going to watch the rag and stick people go round that lump of chalk tomorrow. With a late night like this, I don't suppose you'll be joining us?

David

[Avocet]

oh ..... and JK very kindly wished me a Happy Birthday some nine months or so ago!

[Nos4r2]

Originally Posted by Avocet

I wasn't anticipating you, and Louise has been very quiet recently.

Scurvey Crew and I are going to watch the rag and stick people go round that lump of chalk tomorrow. With a late night like this, I don't suppose you'll be joining us?

David

Unfortunately not. I've got a leak into my blocked off flooding hull to find. Food dye and a couple of gallons of fresh water will be my lot for this weekennd

[Limey Linda]

I am retired, so it is my MFT ( my fnnn time) Loosely based on GMT -7, depending on how bad my hangover is. Go stuff all the rest [including the Brussels idiots] of the jerks that want their own stupid time. Bilges are next.

[Poly]

Originally Posted by Avocet

And if anyone is still reading this: 'Zulu time' = UTC = CET = Central European Time.

? but UTC is not = CET ???

[Avocet]

Quite right: CET = UCT+1.

Apart from in the summer, when CEST (Central European Summer Time) is UCT+2.

[Nick Thompson]

There is also:

UT (Universal Time)

A system of time measurement which conforms to the mean motion of the Sun, and which forms the basis for "civil" timekeeping. UT is defined by a mathematical formula which related it to sidereal time; ie UT is determined from measurements of the positions of the stars as the Earth rotates.

Sidereal day

The period of the Earth's rotation relative to the stars, ie the interval between two successive transits of the same star. Equal to approximately 23h 56m 4s.

Sidereal time

A measurement of time defined by the apparent motion of the stars as the earth rotates. The sidereal time is zero when the equinox crosses the observer's meridian. An object is on the observer's meridian (ie due south or due north) when the local sidereal time is equal to the object's right ascension.

[neilda]

There's Hammer Time, but that was only used in the 80's for a very short while.