Why?:
Have you ever been sailing when it should have been a great day, but out there you found yourself struggling to stay upright. The average wind speed was shown as 15 knots, but the highs and lows were fast and frequent. It would have been nice to have known a "goodness" value. This index is intended to give more meaning to what the data is telling us.

Definition:
This index is based around conditions that I like to sail in where the wind speed is between 10 and 20 knots and any changes are gentle. The index measures the number of times that the instant wind speed is either outside of 10-20knots or differs considerably from the average speed. It runs from 1 to around 140 and so the lower the count the more ideal the conditions are. So far I have had great sailing when the index is below 20 and totally un-sailable when the index is over 80.

How:
The index is produced automatically by a small programme that processes the incoming data and posts the index to the website every 10 minutes.

The Display:
The index is displayed on the web page with a green "A" for great sailing, an orange "B" for marginal sailing and a red "C" when the wind is not all that good. The raw index is available in the historical data page (Power users).