NavList:

Greg,
Yes, your plot looks right to me. The 1200 EP is drawn on the 1200 sun line at the foot of the perpendicular from the latest EP. And the traditional running fix, of course, is right.

I’m not sure how you combined the one-sigma shaded areas. In probability theory these independent distributions (frequently, normal distributions) would be multiplied together. Then the MPP is located at the maximum value of this 2D function. As some of my last plots show (post 23217), this location can be a little counter intuitive in some cases.

But I must say, again, that this probability approach is purely of academic interest, and indeed can be interesting on that level. And as many on the List have said, if the point is avoiding rocks, or other foul things, what navigator wants to be right only 90% of the time. (Well, 90% would be great for treasure hunts.) So for normal practical navigation the question is, what is the outer-most boundary of these combined areas, not one-sigma boundary, but the reasonable absolute maximum. Of course, that’s where some judgment comes in….

Fair winds,
John K

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