2013-02-03

How is your predictor line

So far my sollog utility has been about recording statistics about the boats. First it was storing the history every hour, i.e. the latest data available was the last full hour. Recently I added the almost real time statistics which are updated every minute. (For anyone interested in IT, the latest numbers are only stored in memcached where the web page gets the information.)

Now it's time to look into future. As we now know every boat's location and course, it is pretty easy to calculate where that boat would be if it would continue with the same course (or same TWA). As we also have the weather forecast we can use this information to calculate the wind speed, direction and also boat speed on the predicted point.

This is basically what the predictor line in the game client is, an estimate where your boat will be if you continue without any changes. So far I have calculated the predicted wind speed by changing the weather slider to the desired time and then pointed the mouse on that spot on the predictor line so you will get the wind speed and direction. With this information you can then estimate your boat speed from the polar.

In my view SOL is not about who can calculate best but rather who can make the best decisions (or luckiest guesses) based on the calculated numbers I decided to make this tool for easier calculation. Because sollog updates it's information from the server once per minute there might be few percent tolerance in the calculated numbers so don't rely on them when navigating in really narrow places.

To access the predictor, select the desired race from the races list, then enter the boat name and press the button "Predicted data". The default view is 6 hours continuing the same course (COG) as your boat is sailing at the moment. You can change that to TWA by pressing the TWA-button. If you want to see values for other courses (COG or TWA) set the desired course to the degrees-field and press the TWA or COG button.

Unfortunately for now there is no way to tell which weather forecast the predictor is using. Currently sollog fetches the weather file only every full hour, so after a new forecast you must wait for the next full hour for it to be in use. Before it didn't really make much difference in the way sollog was using the weather data but I will probably fix that soon as definitely has effect on the predicted data.

1 comment:

florina said...

very interesting work,thanks for sharing all this