Is there anything more useless than...

[Tomahawk]

Last years almanac?

True the pilotage information should be similar.... (But they do change year on year as new facilities are built.... Or the RSPB wastes 10000 acres of good food producing land to indulge their hobby...)

But the tide data is useless.... Which lead me to a thought? Does it ever comes back? With leap years we get the same day/date every sevn years.. But do tide times coincide with historical sets? And if so how long do you have to wait?

 

[Jassira]

Last years almanac?

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a politician

 

[neil_s]

I make mine last for three years. I use WXtide for the tidal info.

Neil

 

[RupertW]

I make mine last for three years. I use WXtide for the tidal info.

Neil

Same here for three years. I just used the free tide table that was sent out by whatever Marina I based myself at.

 

[NickRobinson]

2007 on boat, WX Tide and Totaltide for tides/currents

1999 at home, 99p plus postage; after ebayer got postage wrong, he'd have made more putting it in the bin....

Nick

 

[tcm]

i agree with others. I can think of loads things more useless than last years almanac.

However, if you are used to picking up the almanac and it being utterly correct.... i can appreciate the frustration in it being - dang!! - last years info..

But there again, tide wise, that's quite a good discipline, innit? Instead of looking in one book for the info, you actually check carefully, praps double check with others too. And loads cheaper.

Also, um, in other areas of the world, last years almanac is about the same as this year if no tide.

Also, lots of Almanacs 95% of the info is for places you ain't gonna visit.

 

[Poignard]

The sellers of the many out of date almanacs on eBay don't seem to think so!

 

[dratsea]

Hi Tomohawk,

Yes I also retain some old Reids for secondary port information, Faversham comes to mind.

But I also keep the old CA almanacs because Dover Harbour publish on their website tides for next year. If you have old tide info including Dover, CA and most others do, just find similar tides at similar time of day (best looking two years ago as lunar year 13 months). Now write in your log "using tides of" say 20th may as doing this as the echo is alarming is not the easy way!. Now go to your port of interest on 20th may 2010 and the info is as accurate as the variation from predicted in this years almanac.

Yours in coral using a leadline as the echo has stopped working.

John

PS for your local sailing in Essex PLA wedsite has all local ports for nest year to 18 months free for download.

 

[ma99ing]

Tides recurring

Hello Tomahawk

Yes the tides would come back eventually I think, as they are comprised of a series of harmonics, or waves due to the gravitational pull of the moon and the sun. They each have a different period, eg the principal lunar harmonic has a period of approx 28 days, - hence your spring tides on new & full moons, other longer period solar harmonics may extend over a year.

Just how long you'd have to wait, I'd have to research a bit further, but by the time it did come around, technology will be able to send the tidal wirelessly to your chart plotter !


"Which lead me to a thought? Does it ever comes back? With leap years we get the same day/date every sevn years.. But do tide times coincide with historical sets? And if so how long do you have to wait?[/QUOTE]

 

[AntarcticPilot]

There are a LOT of harmonics involved, so the exact same tides won't recur in any time short of geological epochs, and continental drift will have thrown things off by then! You have the diurnal components from the rotation of the earth, the monthly component from the orbital period of the moon and the annual component from the Earth's orbit round the Sun. Just for comparison, similar eclipses recur at about 19 year intervals (Metonic Cycle) - but the similarity is off by many hours, as this cycle doesn't include the rotation of the earth. You'd (roughly) need to consider the least common multiple between the earth's rotational period, the moon's orbital period and the Earth's orbital period, so the cycle for tides would be MUCH longer for tides to repeat with a usable accuracy.

Hello Tomahawk

Yes the tides would come back eventually I think, as they are comprised of a series of harmonics, or waves due to the gravitational pull of the moon and the sun. They each have a different period, eg the principal lunar harmonic has a period of approx 28 days, - hence your spring tides on new & full moons, other longer period solar harmonics may extend over a year.

Just how long you'd have to wait, I'd have to research a bit further, but by the time it did come around, technology will be able to send the tidal wirelessly to your chart plotter !


"Which lead me to a thought? Does it ever comes back? With leap years we get the same day/date every sevn years.. But do tide times coincide with historical sets? And if so how long do you have to wait?

[/QUOTE]

 

[Tomahawk]

So ........... a very long time?

I did suspect it would take a very very very long time. I just popped the question in the remote possibility that some very clever chap on the forums had worked it out.. Ho hum

Many thanks anyway for the answers..

 

[Koeketiene]

Last years almanac?

True the pilotage information should be similar.... (But they do change year on year as new facilities are built.... Or the RSPB wastes 10000 acres of good food producing land to indulge their hobby...)

But the tide data is useless.... Which lead me to a thought? Does it ever comes back? With leap years we get the same day/date every sevn years.. But do tide times coincide with historical sets? And if so how long do you have to wait?

Monday comes back once a week.
January comes back once a year.
2011 will come back - it'll just take a bit longer.

 

[sailorgirl]

Also, lots of Almanacs 95% of the info is for places you ain't gonna visit.

I wish you could tell my Skipper that. Last year and this I have purchased the (slightly) cheaper ring bound edition of Reeds based on the fact that our current stint overseas is curtailing our UK sailing which in turn means we won't be reaching 75% of the places listed even in the Channel Edition during the year. Instead of being complimented for saving money he complains like mad every time he has to use it as its not the same!

 

[temptress]

I wish you could tell my Skipper that. Last year and this I have purchased the (slightly) cheaper ring bound edition of Reeds based on the fact that our current stint overseas is curtailing our UK sailing which in turn means we won't be reaching 75% of the places listed even in the Channel Edition during the year. Instead of being complimented for saving money he complains like mad every time he has to use it as its not the same!

AH - got you. This years cruise will take us past the 'cheapo' almanac so we will have to buy anotherone - no saving!!!!!

 

[dratsea]

Yeah,

But have crossed Thames with tides 2m below prediction. Essentially HW = mer pas moon plus a bit, but bit might be up to 6 hours!

 

[ffiill]

The sellers of the many out of date almanacs on eBay don't seem to think so!

Even better the sellers of 10 year old Nautical Almanacs as in Sun and moon;LHAs;GHAs sight reduction etc. which are useable for two years.
Even seen these advertised on Amazon?!

 

[binch]

Tidal harmonics

There are 32 harmonics that affect tides, many of them only marginal.
The hydrographer sells a CD with about 2000 years of tidal data for the whole world on it and it draws pretty graphs too.
It is quite cheap. Try it.
I use it all the time.