Note to Users in Certain Countries:


With version 2.2, Tide Tool has restored 44 locations in the U.K.  Unfortunately it is still not permitted at this time to furnish tidal predictions for locations in Ireland and a few other locations worldwide.

  Please read this entire page, including the FAQ below, before emailing me. You will save us both some time. I have no further information beyond what is here.  
The U.K. Hydrographic Office has taken the position that our use of their tidal information "infringes the intellectual property of the Crown". After a long and fruitless discussion with their bureaucrats, I have removed from Tide Tool all locations in the British Isles, as well as 42 other locations throughout the world (see list below).

The U.K.H.O. asserts ownership of tidal data at a long list of locations worldwide. Initially they claimed data for such locations as Hawaii, but after discussion their list has been somewhat reduced. However, it is no longer useful to argue with them. If you are interested in restoring a location, read on.

Fortunately, another agency of Her Majesty's government was able to provide tidal measurements from which 44 locations in the U.K. have been restored to Tide Tool beginning with version 2.2.

Unfortunately no data was available for the Republic of Ireland, or for the other tical locations around the world for which the U.K.H.O. claims ownership of the data.

If you are a British subject and do not support this action by your government, you may wish to make your opinion known to your M.P. You may also wish to write to the Ministry of Defence, of which the U.K.H.O. is a part.

If you are a resident of another country and wish your location restored, you can help. Contact the authorities in your country who are responsible for tides. Ask them if they can provide harmonic tidal constituents and offsets for locations in your country, for use in a free tide prediction program. Alternatively, ask if they will grant permission for the use of tidal constituents for your country which appeared in the out-of-print publication Table des Marees des Grands Ports du Monde, published by the French Hydrographic Office (S.H.O.M.) based on data from the International Hydrographic Organization database. If you are able to obtain that permission, email me and I will see that the locations are entered into Tide Tool.

The attitude of the U.K.H.O. is inconsistent with that of many other governments. The U.S. government makes all its harmonic constants available freely on the N.O.A.A. web site. The Dutch government recently cooperated with us to make their data sites in the North Sea available.

This action by the U.K.H.O. also affects on-line tide prediction sites using the XTide program, which is the source of the data used in Tide Tool. For details of the correspondence with U.K.H.O. see Dean Pentcheff's tide prediction site.

Frequently Asked Questions:

Will the data files from earlier versions of Tide Tool work with current versions of the program?
No, sorry.

U.K.H.O. offers to license their harmonic data.  Why don't you negotiate a license?
U.K.H.O. will only license "simplified harmonic constants", a small, brain-damaged subset of the full harmonic constants which Tide Tool requires.  Even for this data, they would require a per-copy fee, which is an impossible condition for freeware such as Tide Tool.

NEW:  But that's all changed.  The new, friendly U.K.H.O. now offers royalty-free licenses to reproduce their stuff.
Pressure from frustrated would-be users of Tide Tool and XTide, has helped convince U.K.H.O. to change their policy and make tidal predictions and data more widely available.  This is gratifying.
   However, it doesn't help restore the missing locations to Tide Tool.  Although Tide Tool is free, they consider it to have substantial commercial value and will not grant a free license.  Also, Tide Tool exceeds their limit on the number of ports and/or days that can be displayed.  And none of this alters the insufficiency of their published harmonic data as mentioned above.

Can I generate my own British Isles database to work with Tide Tool?
You would need the harmonic tidal constituents, which you can't get.  (If you had them - the real ones, not the "simplified" - and you were good at compiling C programs, you could download the source code and generate your own databases.  But please don't ask me for help.)
   There is one other possibility.  Given the tide height measurements taken at a location every hour over a year's time, our database keeper could derive the harmonic constants. So if you can find academic or research sites that can furnish that data and can grant permission to use it, by all means let me know and perhaps we can provide some British Isles data.

Can you send me a copy of one of the earlier versions of Tide Tool?
No. What part of "I am not distributing that data" don't you understand?

Can you secretly send me a copy of one of the earlier versions of Tide Tool? I will pay. I promise not to tell anyone. (Yes, this is a frequently asked question. Sigh.)
Sounds good. Do you promise to serve my time in jail - oops, gaol? No? Then see previous answer.

Can you tell me where to find an earlier version of Tide Tool that covers my area?
No, and if you find it somewhere, please tell me so I can see that it is updated.

Why are you so grumpy about all this?
Because I don't enjoy this any more than you do, and my email load has doubled since this happened.

Back to Tide Tool home page.

Page last modified December 4, 2003

Locations outside the British Isles claimed by the U.K.H.O:

Ad Dawhah, Qatar
Aden, Yemen
Akassa, Nigeria
Bandar Abbas, Iran
Bandar-e Lengeh, Iran
Banjul, Gambia
Berbera, Somalia
Calabar, Nigeria
Chittagong, Bangladesh
Cochin, India
Colombo, Sri Lanka
Dar Es Salaam, Tanzania
Davao, Philippines
Dubayy, U.A.E.
Gibraltar (U.K.)
Green Turtle Cay, Bahamas
Hillsborough, Carriacou, The Grenadines
Jazirat Das, U.A.E.
Jazirat Halul, Qatar
Karachi, Pakistan
Kilindini Harbour, Kenya
Ko Si Chang, Thailand
Kota Kinabalu, Malaysia
Kuantan, Malaysia
Legaspi, Philippines
Little Inagua Island, Bahamas
Malindi, Kenya
Manila, Philippines
Mina Al Ahmadi, Kuwait
Mina Salman, Bahrain
Mina Zayed, U.A.E.
Miri, Malaysia
Neiafu, Vava`u Group, Tonga
Pinang, Malaysia
Pointe des Galets, Reunion
San Carlos, Equatorial Guinea
Steventon, Great Exuma Island, Bahamas
Surabaya, Java, Indonesia
Tailevu, Fiji Islands
Takoradi, Ghana
Umm al Hatab, U.A.E.
Zanzibar, Tanzania