rgleason
commented
6 years ago In another issue Sean responded to the question RE checking all the existing polars in the polar folder. Should I remove all columns that have all 0 entries? Is there anything else that should be done?
Rick, If the value should be something greater than 0, and it is for lack of data, then yes, remove it.
If it is 0, because the wind is too high, leave it for now. Most likely I will change the logic so that 0 will mean not to propagate in that direction.
If you really mean to hold position then a very small value of .01 can be used. Sean
However that does not really answer the question why the TWS=28 Interpolated polar with values at 5.2 and 7.0 wanders across and above all the other polars of lesser TWS? When the intention is to reduce sail, head off 10-20 degrees, and slow down in greater wind speeds. Do we have to just add each of the values in this case because the interpolation does not work in these cases?
So actually TWS=28 column should be something like this?
TWA | ...28
52 0 | 0 <---don't go here
60 | 0.1 <---hold your position by fore-reaching or heaving to
75 | 5.5 <---sailing
90 | 5.6 <---sailing
110 | 5.5 <---sailing
120 | 5.4 <---sailing
135 | 0.1 <---hold position by bare poles & sea anchor
150 | 0 <----don't go here.
Attached is an interpolated pol file where the interpolations occur in higher winds, and while the interpolation seems to be working, the interpolated values are a little off if you consider the fact that less progress may be made in heavier winds, particularly upwind. Notice the polar lines for the interpolated values.
I think I should have put "0" in for the higher angles however to be more realistic.