In an effort to track my upwind performance I thought I would look at the VMG from one of my LT races (low wind, low speed and low skill). Anyways it looks a bit weird, maybe the program (GPSspeedreader) only works with higher speeds or lower angles of sailing?
Looks like with the update it takes out a lot of the slow speed info if you have "exclude turns" checked like that on the bottom right of the polar plot. What does it look like with 'include turns"?
Another application, GPS-Results, ignores any speeds less than 5 knots. Maybe you need to look in the settings in detail.
GPS Speedreader is intended for planing speeds. In the polar plots, all speeds below 5 knots are ignored. You only have a few points where your speed is above 5 knots in your session.
Select to expand quoteboardsurfr said..
GPS Speedreader is intended for planing speeds. In the polar plots, all speeds below 5 knots are ignored. You only have a few points where your speed is above 5 knots in your session.
makes sense thanks
awesome app btw
Ahh, just saw the same thing when going out for a really light wind longboard session. The plot looked very similar to thedoor's.
On a longboard, you'd typically tack. If you have a decent longboard and halfway decent technique, a typical polar plot would show pretty high board speeds almost straight into the wind. You'd have to exclude turns, but the timing is quite different from shortboards, since the longboard turns more slowly.
In a session like the one posted by thedoor, it's usually pretty easy to get a good idea of upwind angles by just looking at the angle between two upwind legs. There are a couple of 90 degree angles, but those are probably in downwind legs. The longest leg shows an angle of closer to 80 degrees (just eyeballed not measured), so that's point about 40 degrees into the wind. Quite good, but about 5 degrees less than what I have seen in longboard race tracks.
Anyway, if something like polar plots for low speeds are important to you, feel free to post it as an issue on the GPS Speedreader projects on GitHub (github.com/prichterich/GPS-Speedreader/issues).
Select to expand quoteboardsurfr said..
On a longboard, you'd typically tack. If you have a decent longboard and halfway decent technique, a typical polar plot would show pretty high board speeds almost straight into the wind. You'd have to exclude turns, but the timing is quite different from shortboards, since the longboard turns more slowly.
In a session like the one posted by thedoor, it's usually pretty easy to get a good idea of upwind angles by just looking at the angle between two upwind legs. There are a couple of 90 degree angles, but those are probably in downwind legs. The longest leg shows an angle of closer to 80 degrees (just eyeballed not measured), so that's point about 40 degrees into the wind. Quite good, but about 5 degrees less than what I have seen in longboard race tracks.
Anyway, if something like polar plots for low speeds are important to you, feel free to post it as an issue on the GPS Speedreader projects on GitHub (github.com/prichterich/GPS-Speedreader/issues).
Thank you. I guess I am trying to find that sweet spot between pointing too high and losing board speed versus staying lower and keeping speed up. That session I was sailing with another mate on the LT which really helped too.
It would be great if my watch could give me an estimate of my VMG in real time lol. I guess it needs the wind direction to calculate vmg and that obviously varies a lot. But wondering if without wind direction if the watch could do some math using direction and speed to rate actual to rate beating performance. Perhaps if it could recognise I tacked versus gybe it could assume I am beating???
Select to expand quotethedoor said..boardsurfr said..
On a longboard, you'd typically tack. If you have a decent longboard and halfway decent technique, a typical polar plot would show pretty high board speeds almost straight into the wind. You'd have to exclude turns, but the timing is quite different from shortboards, since the longboard turns more slowly.
In a session like the one posted by thedoor, it's usually pretty easy to get a good idea of upwind angles by just looking at the angle between two upwind legs. There are a couple of 90 degree angles, but those are probably in downwind legs. The longest leg shows an angle of closer to 80 degrees (just eyeballed not measured), so that's point about 40 degrees into the wind. Quite good, but about 5 degrees less than what I have seen in longboard race tracks.
Anyway, if something like polar plots for low speeds are important to you, feel free to post it as an issue on the GPS Speedreader projects on GitHub (github.com/prichterich/GPS-Speedreader/issues).
Thank you. I guess I am trying to find that sweet spot between pointing too high and losing board speed versus staying lower and keeping speed up. That session I was sailing with another mate on the LT which really helped too.
It would be great if my watch could give me an estimate of my VMG in real time lol. I guess it needs the wind direction to calculate vmg and that obviously varies a lot. But wondering if without wind direction if the watch could do some math using direction and speed to rate actual to rate beating performance. Perhaps if it could recognise I tacked versus gybe it could assume I am beating???
There was a watch app I saw that will do that, can't remember the name. It required orienting the watch at the start into the wind and choosing that direction. I just ended up going with the really simple speed/heading app.
You can try with the GPSAR program, I don't remember any lower speed limit there. Below are some data from a Formula session, the tacks and jibes are quite easy to identify and ignore.
