Quote:
Originally Posted by PortsmouthProwler
???
100 yards per minute (I assume that is meant) times 60 minutes is 6,000 yards in an hour which is very close to 3 nautical miles an hour, i. e., 3 knots. Unless you meant three minutes...
Three minute plots? Why? More data? The futz factor in the range alone introduces enough error. Personally, I don't like to keep the scope up for very long, it does not pay to advertise.
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I gather you are not familiar with the 3 minute plotting rule. In 3 minutes a target moving at 1 knot moves about 100 yards. Since the ruler map tool can measure in these units easily many players like to plot in that interval. Just read off the digits it has moved thus far and you know speed after 3 minutes. It's a neat rule to get into manual plotting for beginners. No need to correct for odd time periods and leftover seconds. Simply on the 3rd minute, But I agree, accurate speed, especially when using optical ranging alone, is pretty bad in these short intervals. Averaging the target motion over a longer time is what I would advise at all times to make shot counts. (without spreads I mean)
The futz factor in the range really depends on your position relative to the target. If the AOB is around 90 (on his beam) then the range error leads to a course uncertainty between plots. But when you are infront or behind him, it leads to a uncertainty in how much it moved during the interval.(so uncertain speed) Therefore I like to parallel to his course while keeping on his beam out of sight. Bearing information is then reasonably good to provide a measure of speed. If the time interval is reasonably long for distant targets. And coincidentaly it's pretty much just like your own movement.