Does this site mislead?

[phein]

I went to the weather and tides page here for the first time today, and thought it looked rather good.
I selected Aldeburgh and I was presented with a box headed 'Tide and Weather Data for Aldeburgh'. However, the tide data shown in for Walton ( nearest standard port). The box does indeed tell you that the nearest standard port is Walton, but the impression given is that the data presented is for the port you have selected.
Someone is going to have a nasty suprise one day if they fail to appreciate this.
So, shoudn't this site make it clear what it's telling you, or provide a difference from which a proper calculation can be made?
It spoils what seems otherwise a useful site

 

[DoctorD]

I don't think anyone represents tidal data uniquely for all ports. Even the UK Hydrographic Office only presents standard port data on their website (it's called Easytide - very good by the way - at www.ukho.gov.uk). Maybe an opportunity for someone?

 

[incognito]

Try Autotide at www.linden-software.com, hides all the secondary port stuff... I have been using it for about 2 years now, and it's fine for me.

 

[incognito]

YES, YES, YES !!!!! (Kim pls note)

Checked it out a bit further...
Autotide and Easytide agree to within about 3 minutes, and about .2m HT, .1mLT.
EasyTide tells you that you are using GMT+0000 and no adjustments, AutoTide I have set up to use BST.

The YBW tide calculation suffers VERY badly....

1) It is inaccurate on time by 20 minutes on the spot check I did (so this may or may not be the worst) for low tide, Walton on the Naze for 18-May.

2) It does not state the time as GMT, unadjusted.

3) It IS very misleading, in that it states that the reference port for Burnham on Crouch is Walton on the Naze, but does not say that the data given is NOT for BOC but is for WOTN

4) Having given the misleading info for WOTN instead of BOC, it doesn't provide the secondary port data for you to adjust manually the misinformation given!!

I highly recommend avoiding this tidal info source like the plague, and YBW might do us all a favour by putting in a different link... read the following...

-------------------------------------------------------------------------
UKHO WEB LINKS POLICY
Requests for inward and outward links to the UKHO Website should be made to:

Web Team
Email: webadmin@ukho.gov.uk

Organisations wishing to set up links to our website should contact us before doing so. We welcome links to or from other sites, providing they meet the criteria outlined below

 

[davel]

Re: YES, YES, YES !!!!! (Kim pls note)

Link you kindly provided takes you (via a further link) to a page saying that the product is no longer on the market due to pressure from UK Hydro Office. This is a situation I've seen repeated on all sites I've come across that offer access to UK tidal predictions.

Looks like UK Hydro have effectively created a monopoly situation.

Dave L.

 

[incognito]

and I forgot to mention...

Making a mistake between the reference info given (for WOTN) thinking it is BOC, adds a further 50mins inaccuracy - as that is the difference on that day (just think of the consequences!!!) many people have a bit of trouble with SP's and so take the RP, thinking along the lines "oh, we don't have to worry about a few minutes difference" - BAD habit, could be dangerous on the East Coast, sliding through the Spitway thinking it's still an hour to low tide, so there's plenty underneath......

 

[incognito]

Bloody Appalled !!!

I was gobsmacked when I checked your posting and found AutoTide has been withdrawn due to UKHO pressure. I suggested to Linden Software that they go offshore and do their business (think about freedom of info in the US, and how far UKHO would get in suppressing them there!!).

How Droggy will stop someone like me, who has a copy which expires in 2006, from giving bootleg copies to my pals, is beyond me. Not that I would do such a thing of course - and anyone who alleges that I would will be vigorously SUED!!.

Sadly, my comments on the YBW tide link remains... they should either tighten it up, do it properly (I'd do it for the dosh) or link to Droggy.

 

[davel]

Re: Bloody Appalled !!!

I understand your sentiments. I was similarly indignant when I first came across the practice. I wrote to the Hydro office to complain about their stance. Got a reply back saying that they owned the IPR involved in the calculations used to make the predictions and it was in the interests of the British Tax payer to licence these and prevent unauthorsed use.

Sadly the "offshore" approach doesn't seem to work as they've also closed down UK service from a number of US based sites/programs that offered UK predictions. Of course these guys have simply said "OK, sod you" and continued offering pedictions for everywhere else in the world other than the UK. Nett result, no income for the British Tax Payer, no alternative service for the British Tax Payer, no decent service to the British Tax Payer and a general impression presented to the rest of the world that the UK Hydro Office (and UK Government since it's a a gov't agency) has it's head stuck up it's own a*se !

Dave L.

 

[hlb]

Funny you mentioned that. I looked for the first time today. Didn't get around to finding miss imformation cos the bloody thing didn't fit on my screen, so couldn't scroll down it and find next weeks tides in Plymouth. Weather info also a bit duff. IMHO.

No one can force me to come here-----------
----- I'm a Volunteer!!!

Haydn

 

[mharvey]

Re: Bloody Appalled !!!

I thought we had tried to make it clear that the data was from the standard port (name of standard port given for each location), however point taken onboard and I will have this made clearer. With regard to the pressure from UKHO, they insist on charging for the data.............................

Matt Harvey
ybw.com
matthew_harvey@ipcmedia.com

 

[kimhollamby]

TIDES - IMPORTANT ANSWERS

I've quickly skimmed through all of the posts here, having just logged on. I'm going to bash through some salient points and then if I've missed anything, please let me know.

Firstly, in our ideal world we would have 365 days-worth of tides for the year ahead, perhaps even on a rolling basis, for every harbour listed in the 'nowcast' section of weather and tides. And we would expand that outside of the UK. However, the facts are these:

a) as has been pointed out, official tide info is tightly controlled on copyright. There are some sources to buy from; we use Proudman Labs, who charge us for each port listed. Because of the costs involved we have limited ourselves to a set of useful ports for tidal information up to two weeks ahead. In a recent web survey we were the only site offering official tide times up to two weeks ahead (hit the tides button to view the full two weeks).

b) you will see differences between the times of high water on our site and on others you look at because it depends on how the info is sourced. I have seen differences of as much as 90 minutes when cross-comparing Proudman with other sources, particularly simple harmonic calculations, but Proudman is widely used in local printed tide tables and (I think without checking) the Macmillan almanac. The data comes straight from them and is untouched by us so I would consider it as reliable as you can get (given that all tidal information is never going to be minute perfect anyway).

c) we do have text that says that times are GMT and the tide secton is headed Tide times at [standard port]. If there is a feeling these pieces of info are not prominent enough we are more than happy to look at that. I will also explore with Proudman whether we can buy an accurate set of differences for each secondary harbour, even if we have to display these rather than calculate them on the fly.

d) sites that offer 'any place' type calculations use one version or another of simple harmonic calculations. They produce estimates I would personally be happy to work with, because I always allow a generous degree of scepticism in the calculations I run, but the Proudman figures we provide you with are likely to be more accurate as they are based on much more complex historical data. We've often thought about using some kind of simple harmonic software on ybw.com but at its core that would involve us with copyright issues with the Admiralty and that, in our experience, tends to be a very expensive conversation. This paragraph also probably goes some way to explaining why sites that provide this kind of info (and shareware/commercial software houses) often withdraw it after a period.



In light of the above I don't personally believe we are setting out to mislead; far from it you have data you can trust on this site and as budget allows we will expand the service. Perhaps in fact there should be a simple FAQ there to explain exactly what is on offer? Ditto the weather service.

If it is judged not to be valuable we can in fact make a cost saving by not showing it at all...further comments welcome.

kim_hollamby@ipcmedia.com

 

[hlb]

Re: TIDES - IMPORTANT ANSWERS

All of which is no help to me Kim. Cos the scroll bar is off the side of my screen (If it has one). So cant see tide for Monday.

No one can force me to come here-----------
----- I'm a Volunteer!!!

Haydn

 

[kimhollamby]

Re: TIDES - IMPORTANT ANSWERS

Haydn, is that happening on all bits of the site or just weather?

kim_hollamby@ipcmedia.com

 

[paulrossall]

Re:KIM DUMP TIDE INFO

I reckon I am quite intelligent (Accountant /Yachmaster Theory) and was caught out some 6 months ago by data referring to standard port rather than port brought up on screen (and was suprised that you offer a heading indicating port information will follow and then leave it blank), so I ceased to use the information.
Today I wanted to check out Boston and puzzled over the data until I remembered it referred to the standard port. The information is missleading and I suggest you dump it.

 

[hlb]

Re: TIDES - IMPORTANT ANSWERS

Its just the weather kim. Well not even the weather, just the tide tables. There off to the right hand side of screen, so cant get at the scroll bar. I suppose there is one? All the rest is in the right place or eerr, I wouldn't / couldn't be here!!

No one can force me to come here-----------
----- I'm a Volunteer!!!

Haydn

 

[kimhollamby]

Re: TIDES - IMPORTANT ANSWERS

Thanks for the feedback...we'll take a look.

kim_hollamby@ipcmedia.com

 

[hlb]

Re: Ah But.

I've just checked again. Still not right, but if I go to the top left and click it to maximize. It sort of works better. Still no scroll bar, but I get to see more dates.

No one can force me to come here-----------
----- I'm a Volunteer!!!

Haydn

 

[NigeCh]

Tidal constants (+/- 20 minutes)

Online tide tables are all very nice for passage planning ... but unless you have a computer onboard connected to an aerial linking you to the internet then they are about as much use as a fart in thunderstorm.

Secondary port calculations to 2 decimal places are equally as useless.

If you take any set of tide tables and lets assume everything based on Dover ... then at full and new moon HW is always about 1045 GMT. All you need for the UK is a chartlet showing the co-tidal times relative for Dover to show you the +/- average HW times in hours. The constants on Dover +/- a few minutes are Harwich, Wick and Liverpool.

Of course there are anomolies - South Coast around the Solent and the Menai Strait - there are probably others too.

I've got a pre-UKHO-scuppered WxTide32 which gives me about the same time as Proudman Labs times as it does UKHO EasyTide - But I only use them for approximate passage planning. When I'm sailing it's the moon that counts and it's good enough - As for tide heights and secondary port calculations, I just work on the nearest standard port MHWS's heights ... and sofar that's been good enough.

 

[paul_lomax]

Re: TIDES - IMPORTANT ANSWERS

Hi,

Are you talking about the pop-up window which displays the tide data, or the list of ports on the main weather page after you've selected 'Tides' from the menu on the left?

Paul

 

[incognito]

Re: Tidal constants (+/- 20 minutes)

Nigel,

You are clearly a West Coast sailor, spoiled by all that lurvely deep water.

Over here on the East Coast, we have to get it a lot righter. Going through a swatchway where you know you are cutting it a bit fine, but not to worry, tide'll turn soon and we'll get floated back off --- turns into bumping for an extra hour since the tide turns about an hour earlier up coast at Walton - our nearest Standard Port.

Agreed these things are only forecasts, not taking into account things like non-NTP, but otherwise they are actually remarkably accurate - expectation of time within 5 minutes and depth within 0.2m - due to the length of historical data put into extracting the harmonic constants. As I understand it, the time, heights and range are pretty easy, but the ebb curve is pretty difficult to get spot-on and is screwed up by quite a modest rainfall.

Try just four days at random in a month, preferably during those rare highs: sit on the wall at a Standard Port and watch the time the boats swing and check the depth at the same point each day at the same states of the tide - this will enable you to remove the CD from the equation and see how right they are.