Apr 27 2017
Wednesday – a row in the coxless four
Wednesday is our Masters evening. Of course the Masters rowers of our rowing club do more trainings, but on Wednesday at 6pm we gather and row in the eight.
On this particular rainy and cold Wednesday evening, the turn-up was 5 rowers, and a sixth one called us at exactly 6pm, saying that he was “just now” leaving office. That office being just 45 minutes away in the peak hour traffic. 🙁
To at least do something that resembles rowing in an eight, we decided to pick a coxless four. The fifth guy decided to stay on the erg and wait for the sixth guy.
I rowed in bow seat, and the rest of the crew consisted of Martin “Krocan” (=Turkey), Petr “Bulda” (=Bulldog) and Michal “Míša” (=Bear). So we had a rich representation of the animal kingdom.
The boat was an old Empacher 4-, and we lost 15 minutes because we had to replace the shoes so that Bulda would fit into the boat.
I didn’t really fancy rowing on the bow seat, but I guess being the lightest of this crew (with 75kg, compared to Bulda’s 113kg), it had to be me. I like practicing my sweep rowing, but it takes more of my mental effort to do it well, compared to sculling. You can imagine that I did not have the need to also turn around every few strokes and scan the lake for upcoming traffic. Well, so be it.
All our boats are foot steered from the stroke position, so at least I didn’t have to do the steering. And Míša is one of our rowers who can steer our lake with a blindfold, so the course was always right and I just had to watch out for the traffic.
This was a technical training, so we did a lot of drills.
Some of the drills involved rowing with stops at various places. You can see that the SpeedCoach didn’t really understand that.
It was cold and rainy, but we did make a lot of progress during this short outing. It was fun to row something else than a single, and it had been a long time since I last rowed a coxless four.
May 3 2017
Technique in the coxless four and the new Stroke Analysis plot
Technique in the 4-
Wednesday. The day when the CVK Brno Masters group tries to gather at 6pm and row the eight. Today, there was hope until 4pm. Then, there was an email that one of us had to urgently go to Prague for work.
In the end there were six of us. And it was raining hard, so “Pazdy”, who is recovering from a back injury, didn’t want to row outdoors and chose the indoor rower. I announced that I want to row something else than the single, so in the end “President” took the single, and “The mouth”, “Turkey”, “Bulldog” and I rowed the coxless four. We did mostly steady state but we tried a few 15 stroke intervals at a higher rate/pace. The intervals were not so good, but after we did a few minutes of square blade rowing and alternating square blade/squaring we finally got a bit of boat run.
Revamped Stroke Analysis plot
Today, I revamped the Stroke Analysis plot. This chart is similar to the “flex chart”, the Swiss Army Knife of rowsandall.com’s charting capabilities. Just as with the flex chart, you can chose any metric for the X axis and two other metrics for the Y axis. The difference is that the Stroke Analysis plot doesn’t relate to a single workout, but instead it plots all strokes for a certain time period.
That functionality has been part of rowsandall.com for more 8 or 9 months, but I restricted it to erg workouts. Today, I have added a selector where you can chose the workout mode (water, rower, slides, skierg, snow, etc) and added OTW rowing related metrics.
To show what is possible, I have plotted all rowing strokes between March 1 and May 4 and created various Stroke Analysis plots. Because I use Empower Oarlock related metrics, the data are self-selecting for the single. If you row a lot in different boat types, you will see them all in this plot. In the future I will build a boat type selector so you can filter focus on one discipline.
I also filtered out all “paddle” strokes by selecting strokes at 500 J/stroke and higher.
The effective length seems pretty consistent across the various stroke rates. If anything, I may have a slightly longer stroke at 30spm, and above that the length seems to decreate again. When looking at this metric in the boat, I like to see 90 degrees and higher.
Slip, a measure for how quick I load up the blade at the catch. This metric is clearly lower at higher stroke rates.
Catch angle vs stroke rate. I wonder what the group of strokes at the lower value is, but I suspect it is before I moved the footstretcher.
Wash, a measure for how long you keep the load on the blade before the tap down. Lower values are better. I have started working on this in the course of April. So if I select data from the second half of April to today, it should be better. Let’s check:
Hm. I guess there is work to do.
Finish angle. Again, there is a mix of footstretcher settings in this plot.
Work per stroke. Here I do include “paddle” strokes.
Average drive force. I seem to pull a little harder at the higher stroke rates.
And finally – the peak force angle, i.e. the angle at which I reach the maximum force during the stroke. Most of the data are centered in a 10 degree wide range around 25 degrees (before the pin).
And here is, finally, a power vs pace plot:
I have to adjust the units for pace. Currently, they are in milliseconds per 500m. Of course this plot is not normalized for head or tailwind, but still it is interesting.
How to use the Stroke Analysis
As with many things in data driven rowing, there is not a single answer to this. We are only starting to discover what is possible, and are exploring possibilities rather than focusing on what is useful. Still, I can imagine a few ways to use these data:
Finally, above I have mostly put the stroke rate on the x axis. However, when you use Power instead, the graphs seem to start to make much more sense, even if you include “paddle” strokes. Just an observation.
For Wash, I know quite well what the blob above 20 degrees is. These are steering strokes where I reduce the force on my starboard scull.
Looking forward to discussing and finding more use of these plots. Please explore and share your thoughts.
By sanderroosendaal • Uncategorized • 0 • Tags: 4-, lake, OTW, rowing