28
- September
2019
Posted By : sander
First Impressions with Randall Foils
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So I got some Randall foils because I was curious to see how they worked. They are quite the hype in the rowing world, and they were even used by the LW 1x World Champion (Martino Goretti of Italy), so I was intrigued. I wasn’t too convinced by the explanations of how it works, but I could imagine that there was some effect going on, so why not try them out and measure?

What do the foils claim to do?

  1. They limit the depth of the blade, basically making it easier to avoid the common mistake of pulling the blade too deep. This seems plausible.
  2. The claim to avoid “oar shaft drag” during the stroke, which supposedly reduces the boat speed. This, in my opinion, is based on an incorrect understanding of the relative speed of the oarshaft and the water itself, for the parts of the oarshaft that are close to the blade and may be under water when rowing too deep.
  3. People claim to see 3 to 5% speed improvement using the foils, and claim to achieve those results at a lower perceived exertion. 3 to 5% speed improvement is a huge effect. It would mean a more effective use of energy by 10 to 15%. It would make me 40 to 60 seconds faster over a 6000m head race. I don’t believe this. To me, the claims look exaggerated, but I am willing to accept that there is some efficiency boost other than placebo effect.

In my opinion, claim 2 is based on an incorrect understanding of the relative speed of the part of the oarshaft that is under water and the water itself.

I brought home a set of Randall foils from the WRMR regatta in Velence, and last weekend I glued them to my blades. On Tuesday morning, I set out to test them. I decided for the following test protocol:

  • Paddle up to the 2k start. Row a 8 minute interval at 220W (on the NK SpeedCoach, measured at the Empower oarlock) at a fixed rate of 24 strokes per minute
  • Turn, paddle for three minutes, then row a 2 minute interval at 28 spm and 260W

First, I would row them with a set of unaltered blades. Then I would stand around on the rowing club for about twenty minutes to cool down a bit, and then swap for the blades with the Randall foils and repeat the session. I would use my GoPro camera to record how I was rowing, to check if the foils made me pull the blade any more efficient. I inserted that twenty minute wait to reduce effects of being better warmed up for the second run. All intervals were perfectly doable at a submaximum pace, so there was no risk that I would be significantly more exhausted during the second run.

Unfortunately, the result was not clear, because the wind changed between the two rows. When I did the first run with unaltered blades, there was some tailwind then on the run with the foils. The water was also slightly choppier on that first run. So with those disclaimers out of the way, we can still look at the results.

Run 1, without foils


Workout Summary - media/20190924-0945480o.csv
--|Total|-Total----|--Avg--|-Avg-|Avg-|-Avg-|-Max-|-Avg
--|Dist-|-Time-----|-Pace--|-Pwr-|SPM-|-HR--|-HR--|-DPS
--|04350|00:23:20.7|02:41.0|177.0|21.9|159.6|183.0|08.5
W-|02343|00:10:00.0|02:08.0|239.6|24.8|171.3|183.0|09.5
R-|02010|00:13:20.7|03:19.2|130.1|19.6|150.9|183.0|05.1
Workout Details
#-|SDist|-Split-|-SPace-|-Pwr-|SPM-|AvgHR|MaxHR|DPS-
01|01870|08:00.0|02:08.4|233.4|24.1|170.7|183.0|09.7 - tailwind
02|00473|02:00.0|02:06.7|264.3|27.5|173.5|182.0|08.6 - headwind

Here’s a video of the 8 minute part:

 

Run 2, with foils


Workout Summary - media/20190924-0946010o.csv
--|Total|-Total----|--Avg--|-Avg-|Avg-|-Avg-|-Max-|-Avg
--|Dist-|-Time-----|-Pace--|-Pwr-|SPM-|-HR--|-HR--|-DPS
--|04390|00:23:11.0|02:38.4|180.9|21.9|156.2|180.0|08.7
W-|02292|00:10:00.0|02:10.9|237.1|24.3|168.4|180.0|09.5
R-|02101|00:13:11.1|03:08.3|138.3|20.0|147.0|180.0|07.5
Workout Details
#-|SDist|-Split-|-SPace-|-Pwr-|SPM-|AvgHR|MaxHR|DPS-
01|01813|08:00.0|02:12.4|230.3|23.5|167.8|176.0|09.6
02|00479|02:00.0|02:05.3|264.4|27.6|170.9|180.0|08.7

Here is the video of the 8 minute part with foils:

Some more video comparisons. Here is me paddling and then rowing the 2 minute interval, putting the videos side by side:

The run with the foils is on the right-hand side.

Rowing with the foils was an interesting experience. It feels like the catch “clicks” so much easier, and it’s actually quite a pleasant feeling. Otherwise, I didn’t feel much difference. It’s still rowing.

So looking at pure boat speed I cannot say anything definitive. I managed to hit the same average stroke rate and power quite well, and the differences in split are probably explained by the change in wind conditions. My heart rate was a few beats lower when I rowed with the foils, but that may have been the placebo effect doing its job.

So here are the detailed comparisons:

This slideshow requires JavaScript.

In terms of heart rate and power, I was pretty consistent. In the run without the foils I rated slightly too high near the end of the interval. Work per Stroke was similar between the two runs. Again, no big differences.

I reported that it feels like the blade “clicked” better during the catch. I studied the videos and didn’t see any big difference in blade depth around the catch. The only difference I see is that the V splash around the catch is subdued by the foils.

The blade slip at the catch is actually larger with the foils. It seems I am a little more careful taking the catch.

I got significantly more wash near the finish. That’s not good, actually. The caveat here is that it is recommended to row the Randall foils with a oarlock angle of 0 to 3 degrees. The problem is that the Empower Oarlock is set at 4 degrees and cannot be changed. I don’t think 3 or 4 degrees is a big difference, but I do see a shift in wash, in the wrong direction.

I rowed a slightly longer arc when I rowed with the foils. Checking the catch and finish angles, it shows that I take 1 degree more at each end of the stroke. As a result, the effective length is quite similar. I am not sure this difference is due to the foils. It may just be may row to row variation in rowing. Or the effect of being slightly more tired during the second run. Average and peak drive force are almost equal for both rows.

Today, I did a 6k test (2 times 3k with a quick turn, so half of the test is done with tailwind, and half with headwind) on our lake, using the foils. I did not see a magical speed up by 40 seconds compared to previous runs of this test.

Conclusion

Purely scientifically speaking, I would need to redo the experiment to get some more conclusive results. However, looking at the videos closely, and given the result of the 6k test and the fact that the Empower oarlock was not able to measure any significant differences, I am pretty sure that the foils do nearly nothing for me.

I could imagine that the foils help for rowers who have trouble getting the blade depth right. They definitely help you find that exact handle height where the blade is set correctly.

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