Basic Physics of Rowing (2007) • Hacker News Board

Re: Basic Physics of Rowing (2007)

#41

Post by mikestew » Thu, May 11, 2023, 6:30 PM UTC

throwaway22032 wrote: post #16

inasio wrote: post #11

One cool fact is that rowing offers a bigger efficiency advantage over swimming than biking over running: The efficiency advantage of biking versus running is around 2.66x, the hour record on bikes is currently 56 km (56km/hr), and the fastest marathon run is around 21km/hr. On rowing vs swimming, the current freestyle 1500m record is 14:31 (6.2km/hr), whereas the best time for single scullers is 2km in 6:30 (18.5km/…

21kmh for a marathon is absolutely insane. Somehow I've never put two and two together on that before.

There have been opportunities to try running at world-record pace on a giant treadmill, with a crowd to watch you land on your ass while you try and run at a sub-5:00/mile pace:

https://www.runnersworld.com/news/a23634309/runners-attempt-...

For reference, I believe the pace Kipchoge ran for his world record is about as fast as I ran when I set our high school's 2 mile/3200m record. It's a solid record that I still hold 45 years later, but Kipchoge did it for 24 more miles. Insane, indeed.

Re: Basic Physics of Rowing (2007)

#42

Post by anotherpaulg » Thu, May 11, 2023, 6:40 PM UTC

I have long wondered why rowers row in sync. That causes a burst of speed and power when they all drive and then a lull in speed when they all recover. That burst of speed raises the force of resistance from the water to the cube power.

Rather, why not split the rowers into 2 groups? Have drive while half recover. And vice versa. The speed curve of the boat won't be so peaky. And the cube law resistance from the water will be much lower.

Seems like that would more efficiently turn total power into average speed, and waste less power on overcoming water resistance?

I understand there may be physical issues with long oars not cycling in sync. But perhaps there's a boat design that could solve this?

Re: Basic Physics of Rowing (2007)

#43

Post by ycken » Thu, May 11, 2023, 6:42 PM UTC

germinalphrase wrote: post #15

This seems as good a place to ask an any: is there a best “bang for your buck” rowing machine (or style of machine) for a novice? Edit: thanks!

I have owned a Concept 2 Model D for quite a while. It has been one of my best investments. It just works. There has never been anything that has come close in dollars per work, no gym, no other equipment, not even running shoes.

Re: Basic Physics of Rowing (2007)

#44

Post by parkersweb » Thu, May 11, 2023, 6:48 PM UTC

anotherpaulg wrote: post #42

I have long wondered why rowers row in sync. That causes a burst of speed and power when they all drive and then a lull in speed when they all recover. That burst of speed raises the force of resistance from the water to the cube power. Rather, why not split the rowers into 2 groups? Have drive while half recover. And vice versa. The speed curve of the boat won't be so peaky. And the cube law resistance from the wate…

I’m a rower but with only a very loose understanding of the physics.

My understanding of why you actually want the ‘peaks’ is because there’s a point at which you have to drop the blade back into the water to begin the new stroke. I’d guess you need to do that at the trough of the cycle in order cause the least disruption to the free speed generated.

From experience it’s also definitely true that for a boat to be balanced it’s absolutely essential the rowers move in sync.

Re: Basic Physics of Rowing (2007)

#45

Post by dutchblacksmith » Thu, May 11, 2023, 7:06 PM UTC

ojbyrne wrote: post #19

germinalphrase wrote: post #15

This seems as good a place to ask an any: is there a best “bang for your buck” rowing machine (or style of machine) for a novice? Edit: thanks!

Concept2 is pretty well the standard: https://shop.concept2.com/indoor-rowers/298-model-d-with-pm5...

RP3 seems to be the new standard. It replecates the movement of a boat better.

Re: Basic Physics of Rowing (2007)

#46

Post by prettyStandard » Thu, May 11, 2023, 8:24 PM UTC

prettyStandard wrote: post #38

anonu wrote: post #30

I rowed in a 4 and 8 in college. As we were a club sport, we didn't get much funding from the school. As a result we had numerous ancient watercraft with some newer boats in the mix. It was always a joy to get to row in the newer boats, of course, as they were lighter and stronger. We also had a thing called the "twinkie test". Rowing is a sport where everyone needs to be in perfect sync and "pulling their own weight…

I have heard pulling your weight can also mean your butt lifting slightly off the seat on the drive. I'm not sure which is the case. I imagine the etymology is similar to "way enough" or is it "weigh enough"? Which could have roots in "make way" or "drop the anchor". At this point no one seems to know.

https://www.rowsource.com/cox/weigh-enough

Exaggerated example: https://youtu.be/zvqe9gGruxw

Re: Basic Physics of Rowing (2007)

#47

Post by ninkendo » Thu, May 11, 2023, 11:37 PM UTC

Someone wrote: post #27

ninkendo wrote: post #4

I rowed in high school, and one of the things the coaches always wanted to see is for you to slide forward slowly in your seat as you move the oar between strokes. The reasoning being that as you slide “forward” in your seat, you’re actually pushing the boat backwards with your momentum, since you face backwards in the boat. It always struck me as strange advice though, because in a race you’re trying to get high str…

Coaches don’t necessarily tell you what you have to do, but what makes you do what you have to do. Yes, Olympic rowers move forwards fast in their slides (how else do you do 40+ strokes a minute?), and no semi-experienced rower fully separates the arms/back/legs motions (they tend to blend into each other a bit), but common beginner errors are: - to race the slide, then stop at the catch, causing the boat to pitch (…

> Coaches don’t necessarily tell you what you have to do, but what makes you do what you have to do.

Yup, this was exactly the problem for me. I take the advice too literally and I had awful form until I just relaxed and rowed in a way that felt natural.

I mean sure, you should be starting the catch with your legs first and finishing leaned back with your arms coming in only as you reach the end. But the coaches would exaggerate way too much and tell you to not even start moving your back until you were fully halfway into the stroke. I took this far too literally and locked my back in place for way too much of the catch and ended up making the whole thing awkward and inefficient.

Don’t rush the slide, sure, but the coaches made it seem like you had to inch. Up. So. Slowly, and we did low rate technical rows to hammer this home. I rowed stroke seat in my first race and guess what happened? I went up the slide slowly and ended up rowing at 27 strokes per minute and we lost the race handily. Oops, i guess they forgot to teach us how to actually row fast before we got to our first race. I never rowed stroke after that because I was too used to rowing slowly.

The reasoning behind coaching in a way that causes you to do what you’re supposed to do instead of what you’re told to do, makes sense, until you realize that there are people that will actually take the advice literally. And you’ll overshoot and miss the mark.

Basically: “do as I mean, not as I say” is a shitty teaching style, at least for people like me.

Re: Basic Physics of Rowing (2007)

#48

Post by ninkendo » Thu, May 11, 2023, 11:49 PM UTC

azalemeth wrote: post #7

dutchblacksmith wrote: post #5

Earlier quoted context omitted.

Your coach was right, it was good advice, Olimpic rowers master this to perfection and make it look easy.

And I think that the argument would be that during the return to backstops you would increase the speed of the boat's shell -- leading to a drag term proportional to v^2, in addition to the mean speed of the boat, effectively demanding an increased power on your behalf during the drive to compensate for it. If you move to front stops slower, the bow doesn't surge as much, and the required power is therefore more cons…

You have a certain amount of time (read: very little) to reach the catch if you want to maintain a high stroke rate.

Assuming a fixed time “pulling” in a given stroke, and given two options:

- Row 35 spm and reach the catch slower

- Row 40 spm and have to go faster to reach the catch

I’m pretty sure the latter would win a race. Even though you’re “rushing” the slide and robbing the boat of momentum.

The problem is that the coaches were so adamant about crawling up to the catch, that something has to give, and stroke rate suffers. I know this because after being taught by said coaches, I rowed the stroke seat in my first race, keeping everything in mind the coaches had taught me. I ended up rowing an average of 27 spm and we got absolutely trounced.

Re: Basic Physics of Rowing (2007)

#49

Post by whalesalad » Fri, May 12, 2023, 12:41 AM UTC

prettyStandard wrote: post #36

whalesalad wrote: post #31

reminds me i need to fold all of the laundry that is hanging on my C2 drying rack

Aren't you going to get rowing grease on that laundry?

the chain is completely hidden when not in use (it is not wise to leave the handle in the cradle for long term storage). plus I have not lubed the chain since purchasing it, lol, so it is dry as a bone anyway.