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Is there any tidal information available for Southern Africa on the maps? My montana gps have the tidal option but no information available.

asked 19 Mar '12, 08:48

Oli4eben's gravatar image

accept rate: 0%


By "the maps" I guess you mean "the maps in my Garmin Montana GPS", which may include data from OSM but may also include other information (e.g. elevation information from SRTM). By "tidal information" do you mean "high and low tide location" or "high and low tide time"?

(19 Mar '12, 11:52) SomeoneElse ♦

I believe OP is referring to "tide tables" (http://en.wikipedia.org/wiki/Tide_table ). Apparently, some (mainly marine) GPS can display these. See e.g. http://www.gpsinformation.net/waas/g76/g-76-map.html

(21 Mar '12, 08:07) sleske

No, OSM does not include any tidal information. Arguably such information is out of scope for OSM, because OSM is mostly about information which is constant.

Information which changes regularly is generally not included. Thus OSM will list restaurants with their location and their name (which are reasonably constant), but not e.g. their menu (which may change every few weeks).

So you will have to find tidal information elsewhere.


Based on comments to the question, what you are probably seeing on your GPS unit are tide tables. From what I understand, the tide table downloads that the GPS manufacturers offer only include some base data; the actual tide tables are apparently calculated by the device (this seems likely, because some devices can display them for years in the future).

At any rate, the information required to calculate tides is probably specific to the tide calculation software embedded in the GPS, so even if OSM contained this information, it's unclear if a given GPS unit could use it. So, you'll have to look elsewhere.

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answered 19 Mar '12, 09:29

sleske's gravatar image

accept rate: 24%

edited 21 Mar '12, 08:19

Thanks, I did find it. I have to buy and load "blue chart atlantic" maps on my GPS before any high and low tides will show on the unit. but not cheap ($250) just for the tidal info of Southern Africa.

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answered 21 Mar '12, 08:30

Oli4eben's gravatar image

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question asked: 19 Mar '12, 08:48

question was seen: 3,068 times

last updated: 21 Mar '12, 08:30

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