Ok I have been doing a bit of digging into and number crunching from my GPS trace from Saturday to try and better understand exactly where I have improved and where I am still weak.
I think that the best place to start this is to perform a comparison to a race last year, in similar course, wind and tide conditions. The two courses used in this are slightly different, but they are close enough that the comparison will hold. First, the comparison of the polar diagrams.
Well an improvement is very evident here, with the previous race in blue and last weeks in green. You can see that anything resembling downwind bace was simply non-existent before, and I was obviously struggling to get the boat to even foil downwind. But before you all cry foul and say that the comparison is flawed as there was different wind conditions, let’s look a t blow-by blow of the upwind performance.
Ok straight line speed is similar, if not slower, however I am now sailing around 10º higher than before, which gives a much better upwind VMG. This was mainly achieved by my some rig tweaks that I blogged about here. My tacks, which still suck, suck less now, and I am loosing less speed as I do them, as shown in the chart below.
So how much faster? Try one minute faster on a 9.36 minute leg, which is, you guessed it, 10.3% faster. Another interesting factor is that I actually lapped myself when comparing the old trace to the new one. When you look at the graph below it is easy to see why. This graph shows “height” up the course, compared to time, which works really when when comparing WL style courses like we sail at St. george when the NE blows.
On this chart, the green circles are mistakes (mostly bad gybes), each one costing 1-3 mins. The blue circles are foiling gybes, and you can barley see them, which shows the huge gain to be had by clean foil gybing vs not and crashing.
This graph also shows that I lapped myself at the start of my third lap (for me in ‘09). The 3 lap elapsed time is 51 mins compared to 73 mins, which is a huge 30.2% quicker for the three laps …. fark … and there is still a long way to go.
March 4th, 2010 at 6:40 am
Too much analysis Bruce.
Best answer to first question is ……..
…….Gybing
March 4th, 2010 at 9:50 am
Great analysis!
March 4th, 2010 at 8:20 pm
Hmm,
)
Gota agree with both comments. The gybes were sucky but ( and having the advantage of looking at it blow by blow) the upwind legs still overshoot the top mark, the gybes are slow, but better. The run is not as fast consistently as it could be and the tacks are eating up heaps of time. Having this type of analysis points to the problems and validates your findings. The ability to perform this analysis was not around when we were kids and I am sure that with the benefit of coaches we could have been as good as some ( somewhere
But I think that the biggest issue is all the years of saying that you can’t. There is no substitute for doing it every weekend ( or day ). I noticed last weekend that I have lost race pace, because I have not been racing, but it came back once I got the feel ( after about 15 kmiles ). Keep up the work on the water, there is no substitute for practice.
April 22nd, 2010 at 10:57 pm
I’m not an expert at all but it seems to me that the discontinuity of both polar diagrams shows that there’s not enough data there to draw any firm conclusions based on the shape of the diagrams. And to be able to draw inferences from the magnitudes you’d need to confident that the wind strnegts were exactly the same. But it is very interesting anyway and I would also be trying to suck some meaning from it.
What did you use to genrate the polars and how was the wind direction fed into it?
April 22nd, 2010 at 11:06 pm
The software is a trial version of GPS action replay. GPSar calculates the wind direction based on the track data. The shape of the polars is mainly because of the specific angles that are sailed on the river. But they are around 2 seconds apart.