|
Post by ianr on May 18, 2020 14:43:17 GMT
Hi all,
I have the Polar Chart for my boat but not the underlying data table. I see that Raymarine Lighthouse 3 is now supporting Boat Polars and current Jeanneau boats are included but not the prior models.
I can transcribe from the chart but that isn't going to be accurate to two decimal points.
I have scoured the www but no luck yet. I have asked Jeanneau but don't hold out much hope there. This sort of info should be in the public domain is this data age.
If anyone knows where I can get one it would be much appreciated.
Thanks, Ian
|
|
|
Post by MalcolmP on May 18, 2020 16:08:48 GMT
|
|
|
Post by element on May 18, 2020 17:26:37 GMT
|
|
|
Post by element on May 18, 2020 21:12:25 GMT
If you search on the site above on 4O9 I see there are even 10 ships with a rating.
|
|
|
Post by rene460 on May 18, 2020 23:12:32 GMT
Hi Ian, don’t hesitate to just “transcribe from the tables”.
In my professional career, I had often to do complex dynamic calculations requiring performance curves of expensive compressors, gas turbines, and even very large electric motors, and often the driver and compressor, both acting together. All that was available was tatty old nth generation copy of a copy of the curves originally drawn on a drawing board, many years before. I was able to pick off values to a table and achieve quite acceptable results in some quite critical applications.
With your polar curves, two decimal places might look elegant, but is probably not justified by the data as an actual definition of potential performance. Treat it as a good estimate, not a quality assured laboratory test result. The main requirement is to have a consistent target, which you may or may not be able to achieve. Consistent means not only the same target each time you have the same relative wind direction, but also a consistent change in target with a change in direction. You will achieve this if you check your table by plotting little sections or even the whole table on graph paper, or if you prefer it, in Excel, and make any small adjustments necessary to achieve a smooth curve through any three or four points.
Then keep a note of what you actually achieve against your target, or even by how much you exceed it. Using any polar diagram will help you more than none, and no speed instrument that I know of will give two decimal places anyway. In the end, I don’t think there are instruments generally available which will tell the difference in speed between two racing yachts when one slowly creeps past the other, only a line judge with a good line of sight can do that. Your polar table will give you a suitable target and you can update it later if better data turns up.
And please come back and tell us how you go, and how you find it, having that data on your display.
rene460
|
|
|
Post by ianr on May 23, 2020 18:04:37 GMT
Thank you for the responses.
I have transcribed from the chart - and regraphed th edata and it looks consistent. I have submitted to Raymairne, hopefully they will incorporate it soon.
I will also try it in Opencpn and see it compares to real world performance.
thanks. Ian.
|
|
|
Post by ianr on Jun 7, 2020 20:16:39 GMT
Polar attached for info.
6 8 10 12 14 16 20 25 30 32 3.95 5 5.91 6.35 6.55 6.85 7.1 7.3 7.45 40 4.81 5.9 6.6 6.97 7.18 7.4 7.6 7.7 7.85 50 5.5 6.76 7.2 7.57 7.7 7.85 8 8.2 8.4 60 5.9 6.96 7.5 7.88 8.1 8.2 8.4 8.6 8.8 70 6.06 7.02 7.54 8.01 8.42 8.55 8.75 8.9 9.15 80 6.07 7.07 7.6 8.09 8.4 8.65 8.9 9.2 9.5 90 6.01 7.07 7.56 8.05 8.35 8.8 9.1 9.5 9.9 100 6.19 7.18 7.63 7.93 8.3 8.7 9.2 9.9 10.35 110 6.06 7.25 7.71 8 8.2 8.55 9.1 10.02 10.8 120 5.9 7 7.82 8.05 8.27 8.65 9 9.85 11 130 5.4 6.65 7.49 8 8.45 8.9 9.15 9.9 10.55 140 4.85 6.05 7 7.8 8.25 8.8 9.27 10.15 10.55 150 4.09 5.4 6.4 7.2 7.8 8.15 9.05 10.45 11.55 160 3.6 4.8 5.8 6.8 7.35 7.89 8.8 9.95 12.02 170 3.15 4.22 5.27 6.2 7 7.55 8.4 9.45 11 180 3 4 5 5.93 6.75 7.15 8.05 9.05 10.4
|
|