The industry has been sizing kayak paddles wrong | Hacker News Reader

The industry has been sizing kayak paddles wrong

paddlingmag.com

108 pointstroydavis45 comments

I'm a bit unsure about "the industry" here. It's probably true that whitewater paddlers, as the article suggests, tend to go with shorter paddles than are generally ideal for sea kayak touring. Generally speaking, longer shaft paddles have been available, but it may well be the case that a lot of people don't go with them because it doesn't feel natural based on how they learned to paddle.

(I agree with the basic point that, for sea kayaking, you mostly want to keep your hands fairly low and have a relatively long paddle. There's also a whole discussion around blade shapes but that's a topic for another day.)

ADDED: I did do a fair amount of sea kayaking instruction at one point and the inclination of a lot of students is definitely to hold their hands high and dig in whether because of previous whitewater kayaking, canoeing, fun-yaks, or other reasons.

Whitewater paddles are a fundamentally different beast than flat water paddles. You’re not just using them to move forward, you’re using them to manipulate the boat in all three dimensions. So rigidity is key and leverage is key. Your paddle stroke in whitewater is basically straight up and down and intended for maximal power in multiple directions, not long-term energy efficiency as it is in touring.

Hi mate! I'm super interested in this topic.

Why is having a long paddle with fairly low hands beneficial for sea kayaking?

Do you have any resources you think are good quality that I could find somewhere?

Thanks!

I don't have any specific resources but it's really an energy and muscle group thing. When you paddle--and this is broadly true although maybe more specific to sea kayak touring than other things--you're not primarily using your arms. You're essentially keeping your hands in a fairly fixed location and rotating your upper body to supply the needed force. (Though this applies to canoeing as well.)

Some of the classic books by the likes of Nigel Foster are probably still applicable but I haven't looked at them in years.

Not a canoe expert, but I did guide in the BWCA for a summer in college. I've got about 1,000 miles in a canoe all told, almost entirely flat water.

I paddle with an upright stroke because for a canoe paddle, a pretty efficient stroke has your lower hand down quite close to the blade. If I were to wear a watch while paddling, it'd get wet. Your arms remain straight through the stroke, and the power comes from swinging your shoulders and upper back through the stroke. I find that paddling like this means I use a smaller paddle than I'd be normally given, so my experience squares with the article.

This is from a seat, and a bent shaft is widely regarded as more efficient, which feels consistent with my experience. I've not padded enough kneeling to have an opinion, though the conventional wisdom is that a straight shaft is preferable when kneeling. In any case, if you're J-stroking in the stern, it probably matters a lot less than if you're in the bow.

I've always paddled a kayak the same way, sea kayaks included. Does the power in the stroke you're describing come from twisting your trunk in the stroke or is it higher as I've described, or something else? If it's higher, how do you put those muscles to use with the lower stroke?

I can see that you likely save energy not lifting the ends of the paddle high in the air on each stroke, but I've never worked out or been taught a stroke that makes sense for a longer paddle and a flatter stroke.

Canoe and kayak strokes are different because kayak strokes alternate sides. The recovery of one kayak stroke is the same motion as the beginning of the next. Whereas a canoe stroke has a more linear progression of phases since there is one blade. Each forward stroke fully completes, and you reset before taking the next.

Power/endurance for kayak strokes comes from the lower core: the obliques and lower back muscles. The muscles you would use to twist from side to side about your spine. Imagine laying on your back with your legs sticking straight up; now keep both shoulder blades against the floor while you swing your legs from side to side. Those are the muscles for kayaking.

A smooth kayak stroke looks like the balance wheel in a mechanical wristwatch, smoothly swinging back and forth with no hitch or pause. The body doesn’t pitch forward or backward, just twists.

In sea kayaking you're usually going longer distances, so being able to get into a steady efficient rhythm is important. Quick maneuverability is important, but it's not the highest priority. Wind also comes up a lot in sea kayaking, and being able to keep your paddle low is helpful.

Also unless something's gone horribly wrong you're less likely to need to push off the bottom or fit your oar between your kayak and nearby rocks.

That's quite interesting as I learnt to kayak in rivers and indeed it never occurred to me to do anything different in the few times I've been sea kayaking...though in those cases I remember being frustrated about how long it took to get from point to point. Thanks.

Funny enough, rowing, in all it's Olympic glory still isn't sure what the optimal oar size or length is. There's some contention over what the right surface area and geometry is with many higher performance groups using older designs now as they feel the current generation is oversized and with too short a shaft.

Olympic rower here - You're right there has been a shift towards Concept2 Comp blades in sculling (and with that a reconfiguration of oar, inboard, and outboard length). It seems sweeping is still firmly committed to big blades and I would say the oar length is fairly standardized in boat classes within ~1cm.

It will be interesting to see how many scullers (or sweepers) adopt the comp blades at the next World Championships and Olympics. I wouldn't consider those blades an "older" design, though feel free to correct me as I may not know my history here.

Of course, the "right" answer for racing may not be the same as for someone doing relatively recreational paddling. I assume it's very situational--including for the individual involved.

Recreational paddlers generally aren't going to notice a difference at all. The issue is balancing losses from force vectors, the blades pushing and pulling towards/away from each other at the extremes of the stroke, and fluid dynamics where the larger blade has higher flat plate drag and wastes less energy as turbulence around the periphery. You can't have both without making special (wider pin spread) rigging for the boat which oddly hasn't been played around with much.....

Also of note, lightweight women through open weight men use the same blade area and very similar spread/inboard/outboard measurements. There hasn't been much interest in tailoring the rigging to athletes due to equipment expense and availability limitations, even at the Olympic level.

In Olympic sabre fencing men and women use the same timings which can mean that the women's bouts are actually a fair bit more interesting to watch sometimes because they're slower and more likely to make mistakes whereas the men's game is a finely tuned collision at high speed in the middle of the piste (i.e. unless you fence regularly you'll have no idea what's going on)

I wonder what their advice on the optimal shoe size would be?

What I don't get is why one oar is rotated 90 degrees off the other one. It means whenever I use these double-sided paddles I have to rotate them ever so slightly whenever I make a new stroke. It's annoying and I don't understand why it's done. Does anyone know?

90 degrees reduces the wind pushing the upper blade. Feathering the blades to 60-80 reduces wrist strain (in novice paddlers, who aren't used to the movement) but makes the top blade more susceptible to catching the wind.

And if you play canoe polo, you'll want it to be exactly 90 degrees so the ball rebounds predictably when you block the ball with the paddle.

My words will fail to describe how much I love your comment.

Not only is your comment accurate, but also characterizes your background knowledge in ways I doubt a master author could accomplish in so few sentences.

Human memory is a strange and wonderful thing.

Reading the article and comments brought back floods of memories. Of the exact circumstances when I bought each of the paddles I've owned [I've been kayaking for 35 years, in most disciplines, in 3 countries. So I have bought a lot of different paddles...]. Likewise all the trips, marathon races and canoe polo tournaments in bad weather when wind gusts tried to snatch the paddle out of my hands.

As a kid I used a non-offset paddle (it was paddle you could disconnect, so that was easy enough) and then switched to 90 degrees. Having picked up some paddles two years ago that can be attached with variable angles I found something less than 90 degrees to be more comfortable. My kids and wife all prefer the 90 degrees. I guess it comes down to personal preferences. I never did real long distance sea kayaking so, mostly lakes and rivers and some easy white water when i was a lot younger.

The movement of paddling has a natural rotation of the shaft when you raised the fixed hand for a stroke on the other side, it's quite straightforward to figure out sitting and mimicing the movement.

During this movement if the blade aren't feathered at all you have to compensate with some bending of the wrist. The amount of rotation of the shaft induced depends on how much you raise the hand/elbow, and so is fairly dependent on your style of stroke. This is the main way I think should be approached feathering: how much vertical do you intend to paddle? From there the angle should follow to optimize for the least amount of wrist twisting.

In general paddling very vertical will come with more angle in between the blades. I practice slalom and use to have 70-80 degrees crossing, but I tend to paddle less vertically now (aging? Lack of training?) and I'm down to 60 degrees comfortably now.

I have never believed this argument. In particular, I, and my bones, joints, etc, are approximately symmetric under left-right reflection. This means that I am not chiral, and I would expect an optimized paddle that I hold, symmetrically, in two hands, to be similarly non-chiral. (It’s a paddle, not a oar!)

More concretely, if some biomechanical factor made it a good idea to rotate the top of the left paddle forward θ degrees at the start of the left-side stroke, I would want to rotate the top of the right paddle forward θ degrees at the start of the right-side stroke. But with a feathered paddle, one of those thetas is positive and one is negative.

This is wrong in a way that used to bother me deeply whenever I kayaked. I would unfeather any unfeatherable paddle I used to restore proper symmetry.

I suppose what’s really happening is that people feather to reduce wind resistance or because that’s how they learned, and once they’ve learned it, it feels natural.

I would be willing to believe that feathering either direction is somehow biomechanically superior to not feathering at all and that the symmetry is broken arbitrarily, but I would want to see evidence :)

The asymmetry is compensated thusly: when you feather your paddle, you should grip in only with your dominant hand. It should rotate freely in your non-dominant hand.

Your wrist movements can then be symmetric -- your non-dominant wrist is free to move as you please.

And because you are free to set the feather as desired -- you can set it in such a way to minimize the rotation required of your dominant hand (and, per the above, non-dominant hand) to transition from one half of the stroke to the other.

Last I remember looking into it is the hard 90 degree offset is for wind resistance in open water.

Yes. It's called feathering.

In general, I prefer to unfeather my paddles. (Many good paddles can be adjusted--modula small surface area Greenland paddles.) But there's also an argument that you shouldn't change your paddle orientation so that you can do bracing and other manoeuvres by reflex.

This is why it's done but still sorta of strange to me that this was the way I was taught by camp instructors - even though we never were going for speed. Feels a bit like learning how to ride a bike with one of those aerodynamic helmets even if you aren't really ready to learn racing technique yet.

https://www.sportsperformancebulletin.com/wp-content/uploads...

It's not just racing. Feathering paddles can be really useful generally if wind picks up and you're actively fighting it. Otherwise you're dealing with a lot of resistance with the paddle blade in the air. And I assume there are instructors who just want to instill feathered paddles as the norm you should expect.

I generally disagree but lots of people with more experience than I have don't.

See my comment downthread [1]. You should grip a feathered paddle using only your dominant hand, letting it twist freely in your non-dominant hand. The paddle will then tend to orient itself correctly with minimal wrist movement. (This is probably more true of 30-45 degree feathering than 90-degree.)

[1] https://news.ycombinator.com/user?id=colanderman

My instructor said 90 degrees is an old school. Nowadays people do like 25 only.

in whitewater at least, 45 deg became the norm 25 years ago (except for slalom where closer to 90 was normal). Then it shifted further and now 30 is pretty much standard though 0 and 45 are not unusual.

Does remember me on the story from 2019, in which side a windturbine should rotated. They are all wrong, if they would rotate in the other direction (north from equator) it would be much better (the paper said +11 to 20% better). So allways ask, why is is so since ever ..

A quick search turned up this paper: https://wes.copernicus.org/articles/5/1623/2020/wes-5-1623-2...

Is this the one you're thinking of? If so it sounds like wind shear has a surprising amount of impact on it.

This article also suggests up to 40% losses in downstream wind turbines in a wind farm, which might be addressed by having some turbines rotating the other way: https://www.inverter.com/the-efficiency-of-wind-turbine-in-d...

I wonder how many other "assumptions" out there are also fucked up ?

You don't often see such clear examples of where industrial design impacts the evolution of human practices.

It seems like the feedback loop works both ways - the available paddles inform paddling style and intended paddling style informs the design and manufacture of verities of paddles.

It would be interesting to explore where else these kinds of observable mutual feedback loops might occur.

See also the greenland style paddle, which you can make from a 2x4.

https://greatoutdoorprovision.com/blog/greenland-paddles-re-...

Would it impact Standup Paddlers?

this is a direct application of fluid mechanics, such as navier stokes for the optimal length of the oar, the shape of the paddle, etc.

wrongly?

incorrectly is better, i think.

A slightly strange article, whose premise feels like a strawman.

I've paddled a ton of whitewater, sprint, marathon, canoe polo, touring and sea kayaking.

The only time I ever cared about total length (rather than shaft length) was when I was a canoe polo goalie, and wanted to balance reaching the top corners of the goal (long) with fast acceleration and turns (shorter).

someone posts one article on kayaking and the hn canoe polo people just come out of the gd woodwork

canoe polo is kayaking, no?

The claim in the article is that manufacturers focus on specifying total length instead of shaft length.

I'm pretty sure all the big box sporting retailers sell based off total length though? I thought his point was total length is wrong, it's shaft length which matters. Paddle shape and length are independent and surprisingly uncorrelated.

I imagine many frustrating arguments.

Truth is dictated by authority. That's just how our society works. For like 10,000 years. Scientific enlightenment notwithstanding.

Like a network of solipsists.

If the authority told us to cut off our nose we'd be a 90% noseless population inside a week.

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