Dave,
The "wind down" method tells you what drift you will get if you fly a particular heading. You need to "jiggle" to get the wind for the desired track.
Let's take an example. (N.b. I don't have a CRP5 to hand, so I'll make up numbers which are approximate - you will probably get different numbers if you actually work through my example!)
In our example, the wind is 300@20, you intend to track 270 at 90kt. You use the "wind down" method, and find that, if you fly heading 270, you will have 14 degrees of drift, suggesting a heading of 284.
Now, the jiggle: repeat the process, but this time, instead of 270, work out the drift for heading 284. You find that the drift is now 12 degrees. (The reason for the reduction is because you've turned into wind slightly, so there is slightly less crosswind than there was on the heading of 270.)
Ok, so if the drift is now 12 degrees, we need to jiggle again, and try a heading of 282. On that heading, we still have a drift of 12 degrees, which confirms that 282 is indeed the correct heading.
Hope that clears up the jiggle.
FFF
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