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post #9 of Old 04-02-2019
dadio917
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Re: Generic Polars

interesting thread for me at the moment. My wife and I are getting ready for a couple 2000+ mile passages and have been updating com gear over our old SSB/pactor and intreach. Have added an iridium Go and a subscription to predictweather.com. Besides weather forecasts they run weather routes which will help us a) stay in wind and b) maybe avoid too much wind and swell, and c) avoid something worse. The idea is to run the route each day. The routing runs on their servers so the data required to transmit is small.

The routing SW uses boat polars to figure how best to point and how far the boat can get in a given time and condition. Hard to say given all the inaccuracies of weather forecasting how much decent polars add. OR how polars determined for one boat would map to another of the same make but probably set up differently. but still I've been wondering.

Predictweather lets you choose from their data base of polars, a detailed set of data one could measure, or just put in a few rough guesses at how the boat will do at a few angels to the wind in 15knts. They don't have polars for a Valiant 39 but do for a 40. What I've been playing with is derating the V40 by 10% to make up for the hull size. Their SW allows for that. I guess after a week or so at sea we'll get calibrated.


Anyways...that's why I've just discovered a use for boat polars and would love to find some data base that has a Valiant 39.

Dadio917
Valiant 39
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