Ok, now you have me confused.
If you're plotting a single point on a map, it doesn't matter if you're moving or stationary, or what direction or speed you're moving, the point is still on the same place on the map and doesn't move.
Once you've plotted 3 points 3:15 apart and they're in a reasonably straight line and the same distance apart, you've got the course and speed. If they aren't in a straight enough line or aren't the same distance apart, keep plotting until you've got three that are, as long as the target itself is not trying to evade you but moving in a straight line. If it's already evading, you have other problems.
When I'm plotting my 3 points, I'm often running at ahead full on the surface using the WO's nearest visual contact reports. (Edit to add: I've got map contacts turned off.)
If you're talking about using hydrophone bearings, it's easier to do it while stationary, but it can be done while moving... generally.
Hook
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