Help with target speed estimation.

[MaciejK]

Originally Posted by Bilge_Rat

There are various methods, I use:

1. if the contact was reported by radio, the report includes the speed or speed range;

2. if you have enough time use the 3 minute rule to get an estimated speed;

3. if you are short on time, guestimate a speed, I sually start with 8 kts for merchant/convoys; 15 kts for warships;

4. plug in estimated speed in Position Keeper and refine to final speed;

5. if all else fails, setup for a snapshot as the target crosses you bow.

Could someone explain the 3 minute rule?