I have some (4) excel calculators based on polars from Vrtouttoulz. They are at http://www.madinstro.net/sundry/navigation/index.html
They are from races that are already finished and may not be much use to you.
Anyway grab a copy and modify them to suit your needs. Before I used Vrtouttoulz I built my own polars (same Excel spreadsheet but not quite as finely grained). It takes time but it's worth it. Every time you get in a new wind zone just calibrate the polar say every 5 degrees starting from 30 degrees to 180 degrees.