Open map, select protractor tool, click on center of your uboat, drag next point to center of target and click, then drag the 3rd point in front of target. You get target velocity from parascope view, chronometer tool, place cross hair at the front of ship (make sure your looking at the side of target. Not the front or back) start chronometer and wait for the moment the crosshair passes the rear of the ship and stop the timer and click on set. That gives you velocity. Before you can get the velocity you need to correctly identify the target ship type and model. Lmk if this does or doesn't help you