Now that I am back home I have had some chance to work with Patrick's Polauto program and evaluate some of the new changes he has made. I want to say that I am very impressed, not only with the abilities that the program brings, but also by his enthusiasm and willingness to look at suggestions for making the program even better.
I began by manually copying polar data from my Nobeltec
VNS program, and entering it, again manually, into the newest version of Polauto. I did this for wind
speeds of 8kt and 10kt, and this was easily accomplished. When finished, Polauto displayed the polar plot diagram attached as Polauto Polar 12-13-13.
Because Patrick had so nicely implemented the conversion of Polauto polars to the .xml format which SailCruiser (NavSim Technologies) uses, I simply renamed the .xml file to .npp (the SailCruiser import
format), and imported the polar into SailCruiser. Opening it in SailCruiser displayed the polar plot diagram as shown in attachment SailCruiser Polar from Polauto.
The final step was to use the polar to lay out a projected sailing course. I set a true wind
speed of 10kt from 0 degrees true, and asked SailCruiser to calculate the appropriate tacks for the blue route
shown in attachment SailCruiser Tacks. You will see from the 10kt polar that the ideal upwind course is 36 degrees off the true wind, and that is what SailCruiser is recommending as the optimum tacking angle with respect to the wind (obviously, the third tack would be shortened to avoid running aground
). As either windspeed or direction changes, SailCruiser will alter the recommended tacks accordingly, based on the polar data.
As I said previously, the algorithms for the tacking calculations are licensed by SailTimer (Dr. Craig Summers), and it would be ideal if the methodology could be incorporated in OpenCpn
. As you can see, the combination of Patrick's Polauto program and a program which can use the polar data to compute tacking time to the destination
would be a useful sailing tool.