Can't Remember Speed Formula

[direland69]

Hi all. Got a new PC and am ready to get back into SH4 after a little break. Someone posted a simple way to calculate target speed a while back but I can't seem to find it. Can someone verify if my memory on this is correct?

1. Mark first position reading
2. Wait some time (say 5 mins) and note it
3. Mark second position reading
4. Measure distance between readings
5. Speed = yards/seconds*2

Does this sound correct? What would the formula be if distance is in NM instead of yards?

Thanks!

[Laconic]

I use three minutes with Imperial measurments. Mark the spot, wait 3 minutes, mark the spot, and measure. Knock two decimal places off of the measurement and you have your speed (so 900 yards = 9 knots). I usually cross-check this with the speed estimation button on the TDC and the speed given when I send in a contact report.

[direland69]

Disregard. It was in WernerSobe's Sonar Only Tutorial...

NM/Minutes*60 = Speed.

[direland69]

I use three minutes with Imperial measurments. Mark the spot, wait 3 minutes, mark the spot, and measure. Knock two decimal places off of the measurement and you have your speed (so 900 yards = 9 knots). I usually cross-check this with the speed estimation button on the TDC and the speed given when I send in a contact report.

I like that. I'll try that too. Thanks for the tip!

[Quillan]

Assuming you use metric measurements, distance covered in hundreds of meters = speed in knots if you time it for 3 minutes 15 seconds. I never bothered to figure out the time frame for Imperial measurements but it should be easy enough with a calculator.

1 nautical mile=1852 meters, and I think I'll go with this since SH4 is based around metric units with a built in converter to Imperial measurments. Assume a target is going exactly 9 knots, and you want to calculate the interval t where the distance covered in t time equals 900 yards.

9 knots = 16668 meters per hour.
1 hour = 60 minutes.
Therefore, 9 knots = 277.8 meters per minute.
1 yard = 0.9144 meters.
Therefore, 277.8 meters per minute = 303.8 yards per minute.
900/303.8 = 2.96 minutes, or 2 minutes 58 seconds to cover 300 yards.

Mark point on map, start stopwatch. Mark point again 2 minutes 58 seconds later. Measure distance between points. Distance covered in hundreds of yards is speed in knots.

This is, of course, assuming my math is correct. :doh:

[Torpex752]

Speed X 100 = distance travelled in 3 min

Distance travelled in 3 min / 100 = speed.

Frank