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NavigationHow much water is really under the keel?

Pascal Schürmann

 · 02.12.2019

Navigation: How much water is really under the keel?Photo: L. Schulz
The same map section of the North Sea, but with clearly different depths (left with old, right with new chart datum)
The depth and height information in nautical charts refers to different reference values depending on the area. How to correctly take these into account when navigating

Zero does not always equal zero. This is particularly true for navigation - specifically for chart zero. This is defined differently for the German North Sea, for example, than for the German Baltic Sea. Denmark, Sweden and Norway, on the other hand, base their depth and height data on yet other reference values, from which the true current water levels can then be derived.

This should be borne in mind by anyone moving from one country to another in a shallow archipelago, for example. Or who wants to sail under a bridge whose clearance is not much greater than the height of their own mast in the sky.

Skipper instructor Leon Schulz has tackled the problem and draws attention to a number of factors that need to be taken into account when calculating the true water depth. His instructions can now be read in the new issue of YACHT (issue 25/2019, available now from newsagents and as a Digital edition available).

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Pascal Schürmann

Pascal Schürmann

Editor YACHT

Pascal Schürmann joined YACHT in Hamburg in 2001. As head of copywriting and head of the editorial team, he makes sure that all articles make it into the magazine on time and that they are both informative and entertaining to read. He was born in the Bergisches Land region near Cologne. He learned how to handle the tiller and sheet as a teenager in a touring dinghy on the Sneeker Meer and on a tall ship on the IJsselmeer. During and after his studies, he sailed on the Baltic Sea and in the Mediterranean. As a trained business journalist, he is also responsible for boat financing and yacht insurance reports at YACHT, but also has a soft spot for blue water topics.

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