How to properly use the ATWA
Post by iconPost by Luis75 | 2020-05-14 | 19:43:11

Hi all! I have a question: when checking the recap of the suggested route sometimes (most of times at 100% zoom) there is a big gap between the TWA in a certain split of time and the ATWA in the same split. I guess this depends from the zig-zag route that Zezo suggests (in particular when the wind direction and intensity is not constant) but I would like to understand how to evaluate and use such value.
Thanks for all the support!

commenticon 3 Comments
Post by iconPost by zezo | 2020-05-15 | 07:43:41
I always use the track tool myself to check the real directions.

Compare the circles against the lines. You can see very well the optimum angles, when the fixed heading falls behind the fixed TWA etc.

The story of ATWA and the fact that the TWA, TWD and BTW don't always add to 360 is that

1) The router has some noise which I'm trying to smooth out
2) With the interpolated wind the wind conditions in the middle of a 10-minute track segment are not exactly the same as in the middle of that segment. So even with the exactly same data the server will move your boat a bit differently than the router.
Post by iconPost by Luis75 | 2020-05-15 | 14:24:05
Thanks Cvetan!
Post by iconPost by GeGaX | 2020-05-15 | 16:53:23
ATWA (& ABTW) is a trigonometric calculation taking into account the 10 min iterations not listed.
It is the average of the TWA (& BTW) instructions from T + 0:00 to T + xx: xx
When there is a change of tack/gybe, the calculation restarts.
I did this because I use it when I work it makes and it difficult for me to connect, so I "smooth" the instructions
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