Most accurate way to plot in navgation map

[Pisces]

Originally Posted by Misosoup

Hi all.
I read this tutorial http://www.paulwasserman.net/SHIII/#...ols%20Required
but i found a difficult problem:ploting the distance between
enemy ship and U-boat ACCURATELY is EXTREMERY difficult.
if there were accident error for 30m,then,enemy ship's HDG will
not be correct and Speed also too.It causes a incorrect aiming HDG
then the torpedo　won't hit!Please give me a advice　to plot well.
Thanks.

How many time do you take in-between plots? The trick is to make multiple plots over a longer period, instead of just two over a short time. Time averages all errors out of the window. Take your time and follow it from a distance for a while. Once you have a handful of plots then you should be able to draw a line through them. Some may be a bit beside it, but most will conform to the direction of the target. For example, make 5 plots (start plus 4) with 3m15s intervals. That takes you 13 minutes. The 3m15s interval is because the distance between point in 100m units works out to be the speed in knots. After the 13 minutes you take the total distance between 1st and last plot and divide by 4, i.e. 3.2km divided by 4 plots is 8 knots. Guaranteed to be accurate to 0.25 knots!

Really, then 30 meters isn't going to be an issue. Patience is a virtue, and pays back in tonnage.

[Misosoup]

I make only 2 plot and interval is 1min
(i usually use Nomograph writen in Wazoo's Tutorial)
it will naturally cause a accident errors...

I'll try these advices!
Thank you very much!

[Pisces]

Originally Posted by Misosoup

I make only 2 plot and interval is 1min
(i usually use Nomograph writen in Wazoo's Tutorial)
it will naturally cause a accident errors...

I'll try these advices!
Thank you very much!

1 minute is really too short. Even if you rely on the watch-officer reporting range in a 100m resolution.

Also remember that 1 degree at the default maximum visual range (8km) is 140 meters wide, double if you use the 16km environment. If the sight direction is roughly perpendicular to the target course, then this 140m is the position uncertainty (accident errors as you call it, I think) that matters in speed measurement. Or if the view direction is roughly along the target course (like when you trail from behind, or are directly ahead), then this position uncertainty will show itself in uncertain target course. So one set of plots with 3m15s is even questionable when you rely on the watch-officer reports alone. Unless you take the plots from the icon locations on the map you simply have to average it over time to get something decently accurate.