Real Navigation ship's log device.

[CoRb]

Originally Posted by vdr1981

I'm not sure will my answer help you in any way but I indeed have noticed that your sub will actually drift few degrees due to sea state or wind (or maybe even hard coded bug with somewhat "realistic" outcome), especially if you travel in a strait line for a long time...

This means that there is indeed one more extra variable in the equation but I can not tell for sure what is it for sure...

Check this screenshot I made a year ago or so...



EDIT:
Of course, I was talking about SH5 with latest TWoS v1.6.08 on board. Not for Stock SH5 with only few mods in it...

On this screenshot I set up the wind speed 0 m/s for the top route and 13 m/s for the second one.

When Navigator plotting Dead reckoning route, even the 2nd line will be like a straight line on his map, like this:

If we had device, which counts our traveled distance and every changed course, we could plot Dead Reckoning like a real Navigator.
Because TheDarkWraith's Dead Reckoning takes our current position like GPS(if set DR without error in the patcher)