Feedback and Bounce. A review of the NELO single scull.

Since my wins at the 2019 World Masters, I’ve often been asked about my Nelo boats. What do they feel like to use? What do I think of them? Why did I buy so many for coaching with? Are they any good for racing? The questions sound simple, but the answers can be quite complicated. So rather than answer them directly I’ll do so in the context of an issue which I believe is hugely important in sculling, and which comes into sharp focus in the NELO: the Bounce factor.

The NELO single scull: a radically different hull design

Why the Bounce matters

The shape of the NELO hull is radically different from that of conventional racing shells: it’s shorter, more flat-bottomed, and it moves through the water in a different way. The family likeness to the kayaks for which Nelo are famous is clearly visible.

And one of the key characteristics of this hull is that if there is a Bounce element in your stroke, it is particularly noticeable.

Bounce occurs when part of your power output goes into a vertical rather than a horizontal direction, driving the boat down into the water rather than forwards, and thus slowing you rather than speeding you up. Bounce is therefore undesirable. So magnifying its effect must be a bad thing, right? Not necessarily. In fact, to the extent that it enables you to diagnose and respond to the feedback you’re getting, it’s a good thing. I’ll go further and say that it can be a tremendously useful training tool.

I’ve been measuring Bounce for many years, in lots of different boats, using sensors such as the CrewNerd App on phones . The main reason for measuring bounce is that it is not always obvious that it is happening, and you can’t tackle a problem you are unaware of.

Reducing the friction

When I was being coached by Sue Appelboom, she taught me to focus primarily on what might be slowing the boat down, and to speed up by minimising these friction variables, rather than increasing the power. Remove as much friction as possible, and let the boat run and run.

In the Nelo, I need no sensors to tell me what I’m doing wrong. The boat is very stiff and responsive, and the shorter hull seems to amplify the effect of a range of technical deficiencies – not just the bounce. If the catches do not go in together the boat changes direction; if I drop my weight into the stern at the catch – it dips into the water; if I dump my weight at all at the finish, the bows dip. And if I am generating bounce, it can feel like setting out to sea in a brisk onshore breeze, even if the water is mirror smooth.

How can this be good? How could exaggerating my mistakes make me go faster? The answer is Feedback, in the scientific sense of “the modification or control of a process or system by its results or effects”. As soon as you become aware of a problem, you can identify it and fix it. Then you’ll be going faster for the same effort.

You’ll be going faster than before – but is that fast enough to beat the more conventionally shaped boats? This is the bottom-line question. Is such a thing physically possible? What do the scientists say?

More like a torpedo

Fluid-mechanics engineers often say that with traditional hull designs, longer boats are faster as they spread the weight and surface area over a longer area, with the boat therefore sitting higher in the water, reducing the wetted surface area. The Nelo sits lower in the water and moves in a different way. An old friend who is highly qualified in these matters, as well as being a very fast sculler (formerly Professor of Flow Mechanics at Imperial College, now teaching at Magdeburg University), believes that Nelo might be onto a good thing: other things being equal, he thinks, their boats could in principle be faster. On his two visits to Bergerac he covered many miles in a Nelo, and improved his speed performance on both occasions.

What’s different about the Nelo’s movement? The main point is that it does not “dolphin” (riding up over the water between strokes, during the rock-over and recovery, then diving back down during the drive) as much as other boats, and tends to travel in a straighter trajectory, more like a torpedo.

The theory is that reducing the boat’s vertical oscillation in this way also reduces the variable drag – resistance which slows the boat down. When the water is smooth, you can see evidence of this from the bow wave. I’ve noticed that there are almost no waves coming off the bows of the Nelo, which is very different to my other sculling boats, all of which produce visible bow waves as the boat rides over the water, pushing the water out of the way. The Nelo hull is designed to cut smoothly through the water rather than riding up and over it.

Reality check

That’s the theory, anyway. How does it match up with real-life observations? Here’s some commentary on the 2019 World Masters in Budapest, which I managed to win in a Nelo against some very high class boats of more conventional shape.

Here I am in the early stage of the race, when still in 7th place. I was tapping the boat along with a fairly short arc. As you can see, there’s a problem with my bent arms at the catch. You can also see that I am taking some of the load with my shoulders and upper back and that my face is not relaxed. This tension is something I need to get rid of: the core must be engaged, but body should be relaxed. When I feel I am sculling well, I feel totally relaxed, with core muscles engaged but not strained. The face then has no reason to be tense. I have not achieved it yet here, but later in the race I concentrate on my breathing, relax my face, shoulders, and upper body. The trigger for this development was the feedback I was getting from the boat.

I try not to look at much data while racing, but I do record it for later analysis. There’s so much of it available that it can be overwhelming – so I tend to pick on one or two key points depending on the circumstances. What I found most interesting about this World Masters race was the fact that with 300m to go I was still far behind the German who has established an early lead. In an attempt to catch up in the final 40 or so strokes, I turned up the leg-drive power to maximum.

Instant feedback

My rating had dropped from 39.3 strokes per minute at the start to just under 36 at the 600m mark. At the 750 m mark, with only 250 m to go, right after I increased the power (which I did as I hit the last 300m), I felt oncoming waves, as if I had hit a wash from a large motorboat. Yet there was no wash: I was simply bouncing the boat! I did not need any data read-out to know this – the boat told me. By immediately identifying the problem, I was able to adjust quickly. Had I failed to notice, some or all of my increase in effort would have gone to waste, and the speed increase would probably have been minimal. But I did notice, and adjusted accordingly. In almost any other boat, the feedback would not have been so quick and clear and my response, if any, would have been slower.

Some boats are designed for comfort; and in such a boat, as in a car with soft suspension, you’re less likely to be aware of a change in bounce. In the Nelo, though, I felt what was happening and knew what to do. I held my legs down a moment longer, smoothing out and calming down the rock-over; I pulled the finish up a little higher and worked on a really clean and smooth extraction, making sure my wrists were as flat as possible, and that for the tap-down, I pivoted the arm from the elbow rather than having any drop in the wrists. I also tried to actively relax the upper body, from the face, and not leap onto the catch, but get connected and squeeze. And despite the rating going up… look what happened to the distance per stroke, which increased due to the fact that I was consciously relaxing to stop the bounce.

Note the steadiness of both the stroke and heart rates after 600m, while the DPS is rising. My practice paddling at rate 23 is normally 10.5m DPS, with a heart-rate at 130.

So, in the last 400m…for each 100m, the rating went up slightly, as did the distance per stroke, resulting in my second 500m being significantly faster than my first.

Back onshore, responding to the deafeniing cheers of my two fans from PTRC

This sequence is the exact opposite of how I won the C Single in the 2011 British Masters, when I went off as hard and fast as possible, got ahead and then relaxed. Then, I was significantly slower in the second half, but had managed to get far enough ahead in the first half to just stay ahead. This is what the German sculler who was leading until the last few strokes hoped to achieve in this race. Unfortunately for him, I was just getting quicker and quicker, and the boat was helping me with this.

Is one approach better than the other? I prefer getting ahead and pushing off, but I knew this was not possible here, where the opposition had much more raw power, with faster and stronger starts, having probably spent a lot more time than me in the gym. The key to this win was being aware of the bounce, keeping the head clear enough to adapt the technique, and thus making the most efficient use of my limited power. The Nelo played a key part in this.

Conclusion

Awareness and flexibility are the keys to efficient sculling. The Nelo’s tendency to amplify technical shortcomings will sometimes seem uncomfortable, but in reality it’s a valuable asset, as it facilitates rapid remedial response.

The scientific issue of whether or not the Nelo can be considered inherently faster than more conventional designs remains an open question. But of two things I’m sure: first, it’s a worthy contender for high-level racing. Secondly, it’s a tremendous boat for training, teaching and learning. And I’ll certainly be buying more of them in the future!

UPDATE:

One thing I failed to mention about this particular Nelo boat is that it raced 3 times in Budapest, and was victorious on each occasion. The two other races were won by Mark Alloway from Tideway Scullers, who is senior to me both in age and number of trophies. He won the F class (age 60 or over), and went on to win a second time in the E class, the younger group than his. He has just sent me the following message:

Most importantly, you didn’t mention that in the last 250m of your race I was screaming at you from the bank to get a move on (I think my language was a little more colourful than that in the heat of the moment) – and that’s why you finally started to move! Nothing to do with the Nelo…..

More seriously, my own observations of how the Nelo moves shows that the bows dip significantly at the finish, which encourages one to sit up at the finish and get a quick, clean finish which is good. However, the dip still happens; I’ve seen it even with Nuno and Pedro who are pretty skilful in their boats. What is key, that I’ve seen from analysing videos, is that the boat doesn’t noticeably slow during this dip – there’s no check on the boat, which suggests that maybe this dip, while probably increasing resistance, also has the effect of cutting the water efficiently; and as you observe, there is very little stern/bow wave produced by the boat.

Of course this is only an observation so you might want to ask Berend if it makes sense scientifically.

Mark Alloway in action at the 2019 World Masters. This Nelo was later sold for a bargain price to a pupil on one of our training courses, who now keeps it in Nottingham. Note: If you’re on the lookout for a good used Nelo, consider a visit to Bergerac, as we regularly replace them. If you’re thinking of buying a new one, the best people to talk to would be John or Sean at Nelo UK, who can be found in the contact section of their website.

3 thoughts on “Feedback and Bounce. A review of the NELO single scull.

  1. It is encouraging to find a person who applies both science and understanding of the need for feel in rowing Perhaps Jurgen could learn a lesson here?

    Liked by 1 person

  2. The reason your boat isn’t slowing down at the finish as the bows dip, is because you’re not appreciably changing the shape of the water line. You’re displacing more water, but much less than a conventionally shaped boat for each cm you push the bow down. If you take a cone and push it into the water, you’ll see much bigger waves than if you do the same with a cylinder (assuming they’re both already in the water at least a bit). So the energy goes into making waves, and not moving the boat forward.

    That is the genius of the Nelo.

    Like

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