Found a merchant once going 16kts (top speed for that class).
Unfortunately, I'm a Type II hunter, so he got away (bad initial position)
Most merchants I hit are going 7 kts, but I always double or triple-check...
1. Speed by map
2. Speed by periscope (length of target divided by time target takes to cross unmoving peri crosshairs, corrected for ownship speed (or just stop or point bow right at him for a moment))
3. If possible, long-term average speed analysis (can be very accurate, use the map for this one)
Two or more of the above will yield great results, then attack at 90AOB!
In case Jim hasn't said it,
BE MORE AGGRESSIVE!
