. SIX MINUTE RULE
The “Six Minute Rule“ is a rule boat drivers live by. Take the speed of anything in knots, multiply it by 2...then add two zero‘s at the end of it. This is the distance in yards the object will travel in six minutes.
DISTANCE (yards) travelled in 6 minutes = SPEED(knots) × 200
For a weapon travelling at 55 knots, 55x2 is 110, and putting two zeros at the end of it, is 11,000 yards. That is how far the weapon will travel in six minutes. The range to hear a torpedo ram fire is on the order of 8-12 kyards. So if you fire and are heard counter fire will eat you in roughly six to eight minutes. Now then suppose you fire and evade at 5 knots, a nice, silent speed popular with the Sea Wolves. 5x2=10 and with the two zeros, is 1,000 yards. The active acquisition cone of an TORPEDO is 5,000 yards in diameter. In other words, you are dead against that weapon.
If you shoot, shoot and scoot. Fire on a lag LOS (LOS =3D Line Of Sight, explained in detail a bit later) and then expect counter fire in roughly seven minutes. You have to be at least 2,500 yards away (half an acquisition cone) before that time or you will be acquired. 2,500 yards, working it backwards is 12.5 knots (call it 13) for six minutes. That is the speed at right angles to the firing LOS you have to use to ensure you are not snapped up. It works and works very well. By the time they can TMA your speed and range, you are out of the cone.
From the THE BLUE BOOK OF SUBMARINE OPERATIONS, by Admiral R.Blue and Vice Admiral Homer
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