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Old 04-08-10, 05:04 PM   #1
Alcibiades
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Quote:
Originally Posted by DCOg View Post
Very well explained - Thank You.
Can you further explain how to figure out the speed of target.

400 meter in 3 min 15 sec = 400 / 100 = 4 kts.

What is the 100? and does the time have anything to do with it.

Thanks for the help
DCOg

The 3:15 rule is just a quick way of getting the target speed without a calculator.


SPEED = Distance / Time
You can of course, take any length of time if you want. For example, suppose that you timed at target for 20 minutes. And during those 20 minutes, the target moved 8km. Then you have distance and time so you can figure out speed.

Then the targets speed is 8km in .333333 of an hour OR 24km/hr.

To convert to knots, divide by 1.852. 24/1.852 = 12.95 = 13 knots.




to illustrate the 3:15 rule. Suppose a ship moved 500 meters in 3:15.

Then it's speed in km/hr = .5km/.05416666hr (3min 15sec = .05416666 hours) = 9.23 km/hr.

And 9.23/1.852 = 5 knots

Last edited by Alcibiades; 04-08-10 at 05:27 PM.
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