[mountainmanUK]

Oh – one thing to note if you ever try anything like this: Ships may appear to be stationary, even with their screws confirmed as unmoving, but the ship will still move when the time compression is sufficiently advanced. In fact, they’ll move back and forth on the map, in a straight line. It’s obviously a bug (like the fact that some tankers are moving despite their propellers being stationary), but it’s good to note that this aspect of the game isn’t consistent.

Makes things a tad more realistic!! Any ship adrift on the sea WILL move, due to the action of winds and tides. That's why bodies etc., eventually get washed up on shore.
It's annoying though, when you have to cut off a convoy attack cos of those pesky escxorts, and find that that crippled T3 has "drifted" miles from where you thought you'd left it!

cheers