Forum Marinearchiv

Hello

I am looking to adjust a Kriegsmarine longitude-latitude position to WGS84 for plotting on a modern map. Does anyone know the values that we have to use?

Thank you

George

Hello, Geosub

Several years ago I was faced with a similar question.
In this context we found out that – at the BSH (Bundesamt für Seeschifffahrt und Hydrographie in Rostock) – there are design documentations for the historical map sheets, so also for those having been used by the Kriegsmarine.
In such a documentation there is also put down which ellipsoid was the reference for the grid's calculation.
If remembering correctly, in our case it was Bessel's ellipsoid of 1841.
Its difference to WGS84 proved to be too less (scaling in centimetres) to make it necessary to adjust the given historical positions.

Moreover, one should keep in mind that the exactness of positioning in Kriegsmarine times was limited systematically so that differences of centimetres do not matter at all.
As positions often were calculations of speed and course through the water there was often a difference in the position 'logged' and the position 'true' – resulting in the so-called 'Besteckversatz' that showed sometimes miles of deviation.
Given this as background the difference between Bessel's 1841 ellipsoid and the WGS84 ellipsoid is merely an intellectual problem, not one of real importance in the field (or diving area).

Regards - Hägar