Erg power versus surfski speed

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5 years 9 months ago - 5 years 9 months ago #26827 by ShaneS
One for the scientifically inclined on the forum...

I've started dabbling around on a K1 Trainer erg, working on increasing power output for a given heart rate by tweaking technique, effect of cadence on power, etc. So far the Erg effort (heart rate) and distance/speed line up pretty well with my Garmin records for flat water paddling my intermediate skis (Stellar SR and Swordfish S).

As an example; ~150BPM sits me at about 120W of output and the Erg clocks up ~5,250m in 30min, or 10.5km/h. My average heart rate on a 10km/h 10km paddle comes in slightly higher but there are other factors at play, but I'm surprised its this close.

My assumption therefore is that I should see a steady increase in my average on-water paddling speed as I improve my Erg power output for a given input effort, provided I can transfer the Erg technique improvements into real world paddling stroke.

So .... wondering if anybody has come across scientific papers or has real world experience/knowledge in this area.
I imagine more likely to be K1 based than surfski.

More a subject of personal interest rather than an attempt at thesis level research - but any info to collaborate my little solo experiment is appreciated.

:side:

Fenn Swordfish S Carbon Hybrid - 2016
Fenn Elite S Carbon - 2016
Stellar SR Excel - 2015
Cobra Expedition - 2013
Last edit: 5 years 9 months ago by ShaneS.

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5 years 9 months ago #26828 by Aurelius

ShaneS wrote: One for the scientifically inclined on the forum...

I've started dabbling around on a K1 Trainer erg, working on increasing power output for a given heart rate by tweaking technique, effect of cadence on power, etc. So far the Erg effort (heart rate) and distance/speed line up pretty well with my Garmin records for flat water paddling my intermediate skis (Stellar SR and Swordfish S).

As an example; ~150BPM sits me at about 120W of output and the Erg clocks up ~5,250m in 30min, or 10.5km/h. My average heart rate on a 10km/h 10km paddle comes in slightly higher but there are other factors at play, but I'm surprised its this close.

My assumption therefore is that I should see a steady increase in my average on-water paddling speed as I improve my Erg power output for a given input effort, provided I can transfer the Erg technique improvements into real world paddling stroke.

So .... wondering if anybody has come across scientific papers or has real world experience/knowledge in this area.
I imagine more likely to be K1 based than surfski.

More a subject of personal interest rather than an attempt at thesis level research - but any info to collaborate my little solo experiment is appreciated.

:side:


I'm not sure how well this relates to paddling, but I do have a lot of experience in competitive cycling using a power meter, so here's what I found. When I began training, my peak power output was only 610 watts. Three years later it had increased to roughly 1300 watts. I don't know whether I'll see a doubling in the amount of power I can produce with a paddle in the same length of time, but it may be within the realm of possibilities.

Among serious cyclists, heart rate is now considered a poor indicator of fitness level. Not only is heart rate slow to respond to changes in physical effort, but it's very sensitive to cadence. For example, I can produce the same power at 80 rpm and at 120 rpm, but at 120 rpm my heart rate will be considerably higher. Obviously paddlers can't simply select cadence and power output by changing gears, so the closest approximation would be using larger or smaller paddle blades to achieve the same power output at different cadences.

My technique could definitely use a lot of improvement, so I'm still "cheating" by using my large paddle when I try to beat my top speed records. I've managed to hit 8.1 mph in my Stellar SR, but that's still slow compared to what experienced racers are capable of in similar skis on flat water. When I watch videos of ski racers, it doesn't appear that their cadence is any higher than mine, so I must be doing something very wrong when it comes to technique. It would be great if a power meter could be built into a paddle, as they've done with bicycle pedals. That would be an enormous help to aspiring kayak racers who currently have nothing to go on but a heart rate monitor and a GPS.
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5 years 9 months ago #26835 by gstamer
There is a power meter available for kayakers: kayakpowermeter.com/ .
I'm interested, but haven't seen nor used the device.
A review is at www.dcrainmaker.com/2013/06/checking-power-system.html .
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5 years 9 months ago #26837 by Aurelius

gstamer wrote: There is a power meter available for kayakers: kayakpowermeter.com/ .
I'm interested, but haven't seen nor used the device.
A review is at www.dcrainmaker.com/2013/06/checking-power-system.html .


That's amazing. I wonder though how customers are supposed to supply their own paddle blades. The only way I could do that is by sawing them off the shaft!

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5 years 9 months ago #26838 by ShaneS
That is really interesting, though cost prohibitive. The graphs in the DCRainmaker article are incremented in watts - that's serious paddle power.

I'm sure a company like Bennet could help with the blades, they routinely attache different suppliers' blades (Epic, Meek, Braca, etc) to custom shafts, so I imagine they'd work with a customer on this set up.

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5 years 9 months ago #26845 by Aurelius

ShaneS wrote: That is really interesting, though cost prohibitive. The graphs in the DCRainmaker article are incremented in watts - that's serious paddle power.


Compared to the $1,200 power meter on my bicycle, it's a bargain. But I produce a lot more power on my bicycle. Maybe that's why it costs more. ;)

I'm sure a company like Bennet could help with the blades, they routinely attache different suppliers' blades (Epic, Meek, Braca, etc) to custom shafts, so I imagine they'd work with a customer on this set up.


Very interesting. Who makes custom shafts?

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5 years 9 months ago #26846 by gstamer
I had checked on this at one time when I was considering ordering. The kayak power meter shaft will take many common blades, such as those made by Braca, Jantex, etc, that have a blade socket that fits a circular shaft. You can buy just the blades from many manufacturers. Blades attach with hot melt glue and can be removed with a heat gun.

You can check with the kayak power meter manufacturer as to whether a blade will fit or not.

FYI, Epic blades do not fit. Per the manufacturer:

The Epic blades tend to require fitment to an oval shaft - we do not support shafts that are oval. Please check that the blade socket for the blade types you mentioned are circular.

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5 years 9 months ago #26849 by nell
Replied by nell on topic Erg power versus surfski speed
I spend lots of time each year on a speed stroke / GYM erg over the winter - about 60 hrs per year on the erg and 120 hrs per year on water. I've been doing this for 14 yrs or thereabouts.

To answer your question - yes, you should notice an improvement in water speed as erg speed goes up. Mainly, that improvement will come in the form of increased stamina, so you'll be able to go that same speed for a longer period of time. While overall speed on water should increase, it will not be on par with your increasing erg speed.

Transferring that better erg speed to better water speed is a bit tricky because, on water, better speed is dependent on subtle changes in technique and you'll need to learn / adapt to those changes as you get faster. And, as you get faster, the subtleties get further away from what you're doing on the erg. For example, on the erg, there's no technique for pulling the rope backwards during the stroke and there's no penalty for a poorly placed or sloppy catch nor an exit that's too far back or a stroke that's too long, etc. On the water, the faster you go, the more your power phase gets compressed into a shorter and shorter period of time - where the power needs to be more immediate and precise. Conversely, on the erg, it's easy to load power later in the stroke phase and come to depend on that.
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5 years 9 months ago #26850 by ShaneS
Thank you Nell - you've really neatly summarised what I thought (or feared). Your spread of erg versus water hours is roughly where I think I'll end up too (2x ~1/2hr session on erg through the week, 2x 1-2hr sessions on water on weekends).

I'm putting quite a bit of focus on simulating on the erg how a paddle enters, then moves laterally in water, which as we know encourages good rotation. I do notice if I paddle after an erg session my paddle "plops" into the water on the catch because of the timing difference you mention, until I adapt to feeling the catch in water rather than the artificial feeling of rope grabbing in a pulley.

Luckily I find it easier to get an early (or correct) exit on the erg, which I'm transferring to the water where I know I tend to delay my exit too long. Hopefully I can integrate best of each training method.

Out of interest, what sort of power figures do you train at on the erg? I'm thinking that power and cadence are more important than the theoretical speed/distance displayed on the erg?

Cheers

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5 years 9 months ago #26857 by nell
Replied by nell on topic Erg power versus surfski speed
Actually, I've never looked at watts on the erg - I just leave it at pace per 500m as that's what I've gotten used to. Also, I don't know wattage on the water, either.

One thing that I didn't mention is that I think that it's important to have the erg resistance level equal to or maybe slightly greater than what you feel on the water in your ski. Part of the reason why is that since erg sessions tend to be shorter than on water sessions, paddling the erg at higher resistance seems to be a better use of training time.

On the erg, I also add a very subtle pause just before the catch, more or less letting the "boat" glide for a fraction of a second, to allow the rope slack to be taken up and so my catch is more solid because the rope is now more taut.

Other things I've done to my erg are: I exchanged the shaft for a carbon 68 inch ZRE shaft which has a bit more give and softer more realistic feel to it. I taped fishing weights to the ends of the erg shaft to simulate the higher swing weight of a real paddle, and I added a friction device to the spinning flywheel so that my glide is less and so that my catch phase is accentuated a bit more. My next project is to figure out how to add weight to the flywheel so that the boat feel is heavier.

Back to technique on the erg - it really helps to feel and understand all your force vectors on the water so that you can simulate (and remember!) those exact vectors on the erg over the winter. For example, think of the on/off sequence of power application during the power phase of the stroke, the direction that power is applied, the change in direction of that power during the stroke, and how that power application might evolve from more movement with less force to less movement with more force - and how all that changes as you increase your water speed. Of course, think about all that for both your top arm and your pulling arm.

Over the years, I think that I've understood and improved my stroke dynamics and technique (described in the paragraph above) better on the erg during the off-season than on the water in-season.
EB
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5 years 9 months ago #26858 by ShaneS
Thank you again - I'm really lapping this information up, its surprising how little is out there to guide erg users, your posts have been my main guidance other than a few vague old youtube clips..

I've made a few minor tweaks of my own, mainly to convert the kayak-like set up to a surfski seated position, and a footplate to heel drive on to, rather than the standard foot bar.

SS

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Fenn Elite S Carbon - 2016
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Cobra Expedition - 2013

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