Hi
It seems in 11.21 (and the version I had briefly before - 11.19 I think) ships at Oil Rigs get stuck when fully loaded - and then this corrupts the game so a save cannot be opened. See attached save file made as a test. Not sure if this effects ships generally.
See
http://we.tl/l5s973DEDs
Thank you very much for your report. I have now found and fixed the issue with the saved game, but I cannot reproduce the ships getting stuck (but note that large ships have a very long loading time - mouse over the ship while loading to see how much loading time remains).