Public domain tide data ?

[Boo2]

Anyone know of a public domain data set for tide data for the UK ? I know people out there make money from selling predictions from corrected data but am interested if there are any out-of-copyright tide coefficients available ?

Thanks,

Boo2

 

[Burnham Bob]

I think the differences stay the same so a second hand copy of the PBO almanac would give you the data you need for secondary port calculations - but you would still need a source of primary port data. If you have a smart phone, Absolute Tides from Google Apps will only cost you a coupe of quid for a year's data that provides primary and lots of secondary port tidal data with no working out and no hassle so hunting round for a free source does seem a bit like hard work that's not needed.

 

[Boo2]

...hunting round for a free source does seem a bit like hard work that's not needed.

Yes, but I need a public domain / ooc source of tides data, as per my question ?

Boo2

 

[Amulet]

I follow this thread with interest. UKHO EasyTide only gives predictions a week ahead. A large number of software packages that have licensed tide data from UKHO give predictions only a few days ahead. This makes me think that the UKHO data are not in the public domain and that the "forward look" limitation comes from license agreement. I.e., it'd be dead easy to do it for ever into the future, but the license disallows it. Also available are the "harmonic constants", which enable those who know more than me to write systems to calculate tides from first principles. A number of tide calculators seem to do this, and are often somewhat (and occasionally significantly) different from the almanac tables. My old nav software (Maptech Offshore Navigator) only ever gave two years' data at a time, and last time I spoke to them they were in negotiation with UKHO for the next lot of "data". I d not know whether this negotiation is aimed at genuine release of content, or simply the right to do the calculations themselves.

Someone more knowledgeable than me (like ArcticPilot) may well correct my technical understanding.

Thus I have the suspicion that UKHO have to earn money selling the data (that were created with your tax money). Now, before anyone blows their top, I suspect that the current government told them to try to earn their living this way. I.e., I doubt that the policy comes from the poor sods at the UKHO.

And, since I'm mid-rant... many are outraged at the NHS information centre selling health data for research purposes. Even politicians join in the slagging off. Now, whether or not you think the data should be shared for the benefit of research, you should realise that the reason the information centre shares the data is because the government told them to do so and earn some money. It would be quite simple to pay their entire costs out of taxes and tell them to keep the data in house. The poor sods who run the centre should not be taking the flack for this.

 

[pvb]

Yes, but I need a public domain / ooc source of tides data, as per my question ?

You can get free annual tide tables at http://tides.mobilegeographics.com/

 

[Boo2]

... Also available are the "harmonic constants", which enable those who know more than me to write systems to calculate tides from first principles...

Yes, it's the harmonic constants I'm after, anyone know where a set is available ?

Thanks,

Boo2

 

[ronsurf]

Try the Proudman Oceanic Laboratory (http://noc.ac.uk/data)
They have developed their own harmonic constituents that are used in WXTide and the like. I've used them for tide level data in the past.

 

[Amulet]

You can get them from UKHO, but I don't know under what terms. See: http://www.ukho.gov.uk/AdmiraltyPartners/FGHO/Pages/TidalHarmonics.aspx

I may have been maligning them. Maybe they are in the public domain.

Yes, it's the harmonic constants I'm after, anyone know where a set is available ?

Thanks,

Boo2

 

[ronsurf]

I would email these people and see what they can do: enquiries@bodc.ac.uk

Harmonic constants are published in the Admiralty book (iirc)

 

[JumbleDuck]

I remember a discussion about this some years ago, and elsewhere. I think the conclusion was that a limited subset of the harmonic constants (ie some of the terms) is available easily from UKHO, but that if you want the full set you have to pay them substantial sums. The context was a discussion of the possibilities of reverse-engineering a full or fuller set from publish tide tables, from which the conclusion was that it's probably theoretically possible, but not worth the effort. It's not as if the tides stick to the tables anyway ...

 

[Boo2]

Thanks to all for the replies, I will check out the sites posted.

Boo2