Mareographe is the Heuer version of the Abercrombie & Fitch Seafarer, which is described in some detail here.

The Heuer Mareographe was introduced around 1970, and you can find some photographs here.

From time to time, I have seen mention of Heuer Mareographes from the 1950's, but I have only seen them in the 2446C case, shown above (which dates from around 1968-1970).

Click here to see instructions for the Seafarer, which will also explain exactly how the Mareographe works.

Thanks for the question.

Jeff

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: Trying to get info on Heuer Mareographe. It's a
: chronograph with 3 registers. The register
: nearest the 9 has a wheel that shows high or
: low tide, along with a mechanism for setting
: the tide wheel on the left side of the case.
: There is no seconds hand that runs all the
: time. It looks to be from the 50's or 60's,
: but I havent been able to find info on it.
: Thank you.