UTC / Am I being thick?

[Hamma]

I've been looking at this for an hour now. The more wine that goes down the less likely I am to reach the answer on my own... so I need help.

This (attached image) is the 2012 Imray Almancac Tide Tables entry for St Malo. Under Time Zone it says -0100 (French Standard Time). Then it says in bold Subtract 1 hour for UT

The bold bit makes perfect sense - the times are in French Standard Time which is UTC+1. The bit I can't get a handle on is the -0100. What is it referring to?

Further down the page under Sunrise and Sunset the page refers to European Standard time as UT-1. I thought European Standard time was UTC+1?

All the other French ports are similar so it is not a misprint. Why does it say -0100 and -1 rather than +0100 and +1?

 

[nigel1]

This may be pecurliar to ships/boats.
It was called Zone Time (and not time zone).

If a vessel was a position say 15E, she may be keeping a time of GMT +1 (or UTC+1 as they say nowadays)
The vessel was then said to be keeping Zone Time -1, and the -1 being the interval to apply to Zone Time to get to GMT.
Its all a bit horses for courses really

 

[aluijten]

Simple:
Say you live in UT time and I live in French time zone. When it's 15:00 in my zone, its 14:00 in you zone.
The list was made up in French time. So for same point of the tide you need to look at french time directly in the table or subtract an hour from the times in the table if you want to know the UT time at that same point.

A.

 

[rib]

just work in ut all the time

 

[LadyInBed]

Look up Zone Time definition in your Almanac

 

[Conachair]

The bold bit makes perfect sense - the times are in French Standard Time which is UTC+1. The bit I can't get a handle on is the -0100. What is it referring to?

The time zone is an hour ahead, sun rises an hour earlier, everything happens UTC minus 1.

So the UTC clocks are an hour behind CET clocks, 9am in paris is 8am in london. UTC - 1.


But wikipedia says different so I dunno

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

Hang on, nautical time zones.

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

...with negative numbers from −1 to −12 for time zones to the east and positive numbers from +1 to +12 to the west...

 

[rib]

any wiser ?

 

[Sandy]

Are we talking summer or winter time

 

[Skysail]

For navigation purposes the times are designated Zone -0100, Zone -0200 etc as you travel to the East, because the sun rises earlier. Each Zone is 15 degrees of longitude. To the West of the UT (Greenwich) Time Zone (Zone 0000) , Zones are +0100, +0200 etc. This is because in celestial navigation a ship derives GMT/UT from their current Zone Time, not Zone Time from UT.

I agree it is confusing, but it is the convention.

 

[Windy Tonique]

I read it as stating the times quoted are in French Standard time therefore UT will be minus 0100. I don't understand the bit about the shaded areas being French Summertime and having to add an hour? Is that to work out UT or the French Summertime time for the tides?

 

[Hamma]

So what we are saying is, that the Alamanc is telling me how to get back to UTC from the times quoted?

Well - you must be right - there's no other explanation - but the Tables don't contain any explanatory blurb to help with that.

rib We don't have UTC - we have the time quoted in the tables which is French Standard Time which is identified at being -0100.

Gorf We are talking winter time as it happens, but the problem doesn't go away in the summer - it just gets more involved because we then add an hour as well.

LadyInBed The book is silent on the matter - but I agree that would be the obvious solution.

aluijten You must be right - but I can't see the logic in it. It is a British publication - all the other times in it (Dover for example) are in UTC. When I see -0100 on the table I assume it means UTC -1. I am wrong - I just don't understand why.

I reckon it's nigel1 and Skysail who are on the money - but I can't see how I am supposed to know that without access to a pool of experts!

But what about the second section - Sunrise - how do you account for the UT-1 statement? UT-1 is Iceland - not St Malo.

 

[rib]

didnt say utc,have a ships clock on ut time all the time to nav by.and use your personal watch adjusted to local time to do your shopping with.then bst/dst etc does,nt come in to it

 

[Hamma]

didnt say utc,have a ships clock on ut time all the time to nav by.and use your personal watch adjusted to local time to do your shopping with.then bst/dst etc does,nt come in to it

I must be misunderstanding you. UTC/ UT/ GMT and Zulu are all the same time. What do you mean by UT?

 

[rib]

sorry ut =utc etc,im having problems/mis reading your question.(late and wine)i find that if you work to the ut/utc time then local times(regarding dst/bst zone time/ secondary port dont become a such a challange or am i off track here

 

[Skysail]

Try this:

http://www.btinternet.com/~keith.bater/time_zones_rya.htm

.

 

[Hamma]

Try this:

http://www.btinternet.com/~keith.bater/time_zones_rya.htm

.

You are clearly bang on. I've just never heard of it. I now know.

Thanks for clearing that up.

 

[Nostrodamus]

I have prolems with WTZ (wine time zones). I can glance at a clock when having a social drink and read the time. 30 seconds later I look again and it has gone forward by an hour. This seems to keep happening throughout the night to a point where I have real problems because I then get two clocks, slightly out of focus that start to move. I did look in the almanac but could not find any reference at all.
I know it is linked to gravity in some way as when I also drink more I am able to detect pockets of stronger and lighter gravity that can effect the way I walk. There is also a problem with sideways gravity which seems to pull me or push me from side to side. Again there is nothing in the Almanac.
I wonder if the Hadron Collider has something to do with it?

 

[timbartlett]

So what we are saying is, that the Alamanc is telling me how to get back to UTC from the times quoted?

Well - you must be right - there's no other explanation - but the Tables don't contain any explanatory blurb to help with that.

Correct: they are. And they do contain the explanatory blurb -- they say "subtract one hour for UT"

I reckon it's nigel1 and Skysail who are on the money - but I can't see how I am supposed to know that without access to a pool of experts!

But what about the second section - Sunrise - how do you account for the UT-1 statement? UT-1 is Iceland - not St Malo.

I think perhaps the problem is that you are assuming that the terrestrial convention is "right" and therefore anything else must be "wrong". But the first time I had any practical dealings with time zones was in the nautical context, where I was taught that "the name of the time zone tells you how to get back to GMT", so for years I was convinced that the terrestrial system was "wrong".

But the plus and minus are simply conventions: neither is right or wrong, any more than it is right to drive on the left. So long as you stick to the appropriate convention for your circumstances, it's not a problem.

 

[Hamma]

Correct: they are. And they do contain the explanatory blurb -- they say "subtract one hour for UT"

I think perhaps the problem is that you are assuming that the terrestrial convention is "right" and therefore anything else must be "wrong". But the first time I had any practical dealings with time zones was in the nautical context, where I was taught that "the name of the time zone tells you how to get back to GMT", so for years I was convinced that the terrestrial system was "wrong".

But the plus and minus are simply conventions: neither is right or wrong, any more than it is right to drive on the left. So long as you stick to the appropriate convention for your circumstances, it's not a problem.

You're right. If I look at it from the new perspective it is perfectly understandable. I suppose the UT-1 statement means:

For UT subtract 1

---

I don't come at it from a terrestrial context though - I come from aviation which is derived from aquatic navigation. In everything else the disciplines are similar. In this, in so far as there is a comparison, they are opposed. The sea trumps the air though because it must have been this way long before Sir George Cayley launched the first aircraft.

As for Wine Time - my problem is it's always Wine Time, so it's not possible to derive a conversion to Zulu, GMT or even Calling Time. It does occasionally mutate spontaneously to Whine Time though.

 

[marklucas]

Because ...

I've been looking at this for an hour now. The more wine that goes down the less likely I am to reach the answer on my own... so I need help.

This (attached image) is the 2012 Imray Almancac Tide Tables entry for St Malo. Under Time Zone it says -0100 (French Standard Time). Then it says in bold Subtract 1 hour for UT

The bold bit makes perfect sense - the times are in French Standard Time which is UTC+1. The bit I can't get a handle on is the -0100. What is it referring to?

Further down the page under Sunrise and Sunset the page refers to European Standard time as UT-1. I thought European Standard time was UTC+1?

All the other French ports are similar so it is not a misprint. Why does it say -0100 and -1 rather than +0100 and +1?

UTC -0100 (for France, as an example) is the correct way of defining the time zone - because you add the -0100 to the local time (not corrected for summertime) to GET UTC.

Whilst many uninformed sources will say UTC +0100 for France, they are wrong.

And a little bit of trivia - why is it called UTC - Universal Time Coordinated - because the English wanted Universal Coordinated Time and the French wanted Temps Universal Coordine - so the compromise was UTC which doesn't make sense in either language!

Hope that helps.