jimi
Well-Known Member
Left my almanac on boat, what time is HW Dover on the evening of thursday 29/9, pretty please?
tide 29/9
- Thread starter jimi
- Start date
oldharry
Well-Known Member
10.20 & 22.30 give or take a few minutes (derived from my Portsmouth tables...)
jimi
Well-Known Member
Many thanks sir!
Phoenix of Hamble
Well-Known Member
Or precisely...
0843 and 2119 GMT
(from Almanac)
0843 and 2119 GMT
(from Almanac)
G
Guest
Guest
WX on Palm gives : + Belfield ....
LW 04.13 2.41m
HW 09.33 5.50m
LW 16.51 2.07m
HW 22.02 5.68m
And Belfield gives ....
Dover
Thursday, 29 September 2005
04:01 2.6m
09:45 5.1m
16:31 2.3m
22:13 5.3m
Friday, 30 September 2005
04:57 2.2m
10:28 5.5m
17:20 1.9m
22:49 5.7m
LW 04.13 2.41m
HW 09.33 5.50m
LW 16.51 2.07m
HW 22.02 5.68m
And Belfield gives ....
Dover
Thursday, 29 September 2005
04:01 2.6m
09:45 5.1m
16:31 2.3m
22:13 5.3m
Friday, 30 September 2005
04:57 2.2m
10:28 5.5m
17:20 1.9m
22:49 5.7m
claymore
Well-Known Member
Tha's a liberty - richt in ra middle o brekky in ra mornin - an richt in ra middle o bevvy time at nicht - nae day fer a sail.
DeeGee
Well-Known Member
Amiralty TotalTide...
Interesting but slight disparity in these results; these are from TotalTide...
0408 2.4
0944 5.6
1641 2.0
2221 5.6
Interesting but slight disparity in these results; these are from TotalTide...
0408 2.4
0944 5.6
1641 2.0
2221 5.6
G
Guest
Guest
There has been disparity in all sets ...
Belfiled is UKHO data derived ... so should in fact have similar results - but Adm actually use full harmonics, whereas they licence out reduced harmonics ...
Palm and WXtide are based on another set of internationally recognised harmonics - which are available free of charge ...
Even the UKHO will advise you that timings are NOT guaranteed and based on PREDICTION using available data and also experience / data based on past known observations etc.
My way is to use as many as possible and sit in the middle !! I have Belfield, WXTide, C-Tide, Palmtide etc. plus those included with plotting programs ... but I will not quote all the times here ....
i have not run aground or been in error yet based on my tide predictors ....
Oh by the way .... until I got hold of a set of predictions by PC - I often used the 12th's rule + a local tide table card from a chandlers or the PBO Almanac .... but now I'm showing my age !!!!
Belfiled is UKHO data derived ... so should in fact have similar results - but Adm actually use full harmonics, whereas they licence out reduced harmonics ...
Palm and WXtide are based on another set of internationally recognised harmonics - which are available free of charge ...
Even the UKHO will advise you that timings are NOT guaranteed and based on PREDICTION using available data and also experience / data based on past known observations etc.
My way is to use as many as possible and sit in the middle !! I have Belfield, WXTide, C-Tide, Palmtide etc. plus those included with plotting programs ... but I will not quote all the times here ....
i have not run aground or been in error yet based on my tide predictors ....
Oh by the way .... until I got hold of a set of predictions by PC - I often used the 12th's rule + a local tide table card from a chandlers or the PBO Almanac .... but now I'm showing my age !!!!
oldharry
Well-Known Member
What a fascinating variety of different times!
My tide tables state quite categorically the difference between Portsmouth and Dover - and the tide is usually in when the tables say it should be, here. So whats going on?
Does anybody actually KNOW?
My tide tables state quite categorically the difference between Portsmouth and Dover - and the tide is usually in when the tables say it should be, here. So whats going on?
Does anybody actually KNOW?
B
bob_tyler
Guest
Variations due to Global Warming??
LadyInBed
Well-Known Member
Lets get in on the act:
UKHO ETPS gives (BST)
04:32 2.31
09:35 5.49
16:51 1.93
22:11 5.58
UKHO ETPS gives (BST)
04:32 2.31
09:35 5.49
16:51 1.93
22:11 5.58
Phoenix of Hamble
Well-Known Member
OldHarry,
Aren't the differences between Portsmouth and Dover given in most almancs and tide tables not the 'average' difference rather than explicit difference?... and then if you want an exact time, you need to do a proper secondary port calc.. (or in this case look up the correct standard port)...
PS Nigel, I still do use the 'rule of 12ths'... I find it quicker than booting up and checking..... or starting a program.... or finding my PDA etc etc.... and with practice, as you will well know, you can do them darned quickly in your head....
Aren't the differences between Portsmouth and Dover given in most almancs and tide tables not the 'average' difference rather than explicit difference?... and then if you want an exact time, you need to do a proper secondary port calc.. (or in this case look up the correct standard port)...
PS Nigel, I still do use the 'rule of 12ths'... I find it quicker than booting up and checking..... or starting a program.... or finding my PDA etc etc.... and with practice, as you will well know, you can do them darned quickly in your head....
LadyInBed
Well-Known Member
Quite easy to explain IMO.
As the curve approximates to a sine wave, depending on the number of harmonics used, the wave can peak anywhere within half an hour or so of each other, the height of the peak can also vary for the same reason.
As the curve approximates to a sine wave, depending on the number of harmonics used, the wave can peak anywhere within half an hour or so of each other, the height of the peak can also vary for the same reason.
john_morris_uk
Well-Known Member
Its facile to say, but I will say it anyway, tide predictions are predictions.
More importantly the differences that your tide table state between ports 'categorically' are average differences. The differences between ports depend on a number of variable factors.
Total Tide is pretty good usually but I declare an interest in working with people that supply some of UKHO data!
More importantly the differences that your tide table state between ports 'categorically' are average differences. The differences between ports depend on a number of variable factors.
Total Tide is pretty good usually but I declare an interest in working with people that supply some of UKHO data!
AOWYN
Well-Known Member
G
Guest
Guest
Ladyin bed ...
Pretty close to my Belfiled EH ???
I know some go to extraodinary lengths to gain as accurate as possible time ...
But how many in reality time their departure / arrival to the nearest minute ???? I time to nearest 1/2 hour where possible ... nearest hour elswhere ...
So the differencdes really become less important ...
Pretty close to my Belfiled EH ???
I know some go to extraodinary lengths to gain as accurate as possible time ...
But how many in reality time their departure / arrival to the nearest minute ???? I time to nearest 1/2 hour where possible ... nearest hour elswhere ...
So the differencdes really become less important ...
oldharry
Well-Known Member
Printed on the back of the tide tables - which I have left in the boat so cannot check: Portsmouth HW + x minutes = Dover HW. Never had need to check it. Tide tables supplied by local swindlery, so do not know anything about who or how they were calculated - except they seem as accurate as the weather allows for this locality!
Evidently Dover is not + x minutes against these tables.
Evidently Dover is not + x minutes against these tables.
G
Guest
Guest
Tide time differences ...
The difference of tide times bewteen ports is not constant as most people know ... it varies with the tide cycle of neaps and springs ... and of course the part of day it is in ...
The time quoted on back of tide cards - is usually an average calculated time good enough for practical purps !!
The difference of tide times bewteen ports is not constant as most people know ... it varies with the tide cycle of neaps and springs ... and of course the part of day it is in ...
The time quoted on back of tide cards - is usually an average calculated time good enough for practical purps !!