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'Underwater bicycle' propels swimmers forward at superhuman speed

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Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#181

Post by newaccount74 »

diydsp wrote: post #178
malfist wrote: post #172

Earlier quoted context omitted.

Eh, it's hard to tell power output from pedaling cadence unless it's a fixed gear ratio. Most people pedal between 70-100 rpm regardless of the watts they're producing.

There are some clues in their body language. they appear to be straining. And the pedal movement looks a little jerky, as if the load is changing dynamically in relation to the effective flywheel/inertia of the system. Spinning a higher speeds with less torque is supposedly less tiring. So they might want to gear this down a bit and include a larger flywheel/inertia. Very impressive device tho. Maybe a hybrid approac…

To me it doesn't look like it they were struggling with the physical exertion, but it does seem like they are struggling to properly hold on to the boat. It looks like the boat suffers from poor ergonomics, and needs some proper handles for holding on and steering.

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#182

Post by globular-toast »

neerajk wrote: post #27

> The nominal mode enables motion through the water at 3.6 km/h, and for speed-seekers, the SEABIKE can reach a maximum of 7.9 km/h – much faster than normal swimming speeds or even flipper-assisted swimming. https://www.nauticexpo.com/prod/seabike/product-68606-564117... Pretty fast, but "superhuman"? For short distances Michael Phelps can swim faster :)

For short distances Usain Bolt can run faster than most people can cycle.

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#183

Post by why_at »

robjan wrote: post #115

From the looks of the scuba diving video, it looks worse. There's way more leg movement and it looks less controlled (and more likely to damage corals/kick up sand from the bottom) than slow finning.

Given the number of times I've been kicked in the face by another person's fins while scuba diving, I wouldn't want to be anywhere near someone using one of these.

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#184

Post by matsemann »

gklitz wrote: post #51
uncertainrhymes wrote: post #35

I swim because I enjoy it, not because I'm trying to get somewhere fast. This seems awkward and I bet you have to use your arms just to counterbalance the twist you'd get on each 'stroke' of the leg. So even though I think it's goofy, I bet I'd like whoever came up with this. Someone who put a ton of effort into building something they thought would be interesting despite a thousand people telling them it's goofy. Go…

> I swim because I enjoy it, not because I'm trying to get somewhere fast. I run because I enjoy it, not because I’m trying to get somewhere fast. But I also bike because I enjoy it, not because I’m trying to get somewhere fast. You seem to assume that because this thing is faster, it must automatically be less enjoyable. That’s not the case for bikes, why should it be the case here? In my opinion it sounds fun, and…

But if you wanted to swim fast you could just use flippers, and be much more agile.

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#185

Post by matsemann »

julianeon wrote: post #98
rhaps0dy wrote: post #12

What's the advantage of this over foot fins?

I can think of a huge one. I live near a fairly dangerous ocean in SF where I’ve gone bodyboarding with a wetsuit and fins. I’m concerned that, if caught in a current, fins are not enough to propel me out of it. This would. The extra power and ease of propulsion could make all the difference.

Didn't look to go much faster in the video than what I can do with my freediving fins.

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#186

Post by dyauspitr »

globular-toast wrote: post #182
neerajk wrote: post #27

> The nominal mode enables motion through the water at 3.6 km/h, and for speed-seekers, the SEABIKE can reach a maximum of 7.9 km/h – much faster than normal swimming speeds or even flipper-assisted swimming. https://www.nauticexpo.com/prod/seabike/product-68606-564117... Pretty fast, but "superhuman"? For short distances Michael Phelps can swim faster :)

For short distances Usain Bolt can run faster than most people can cycle.

For very, very short distances I can run faster than most people can cycle.

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#187

Post by 0xDEADFED5 »

rcruzeiro wrote: post #168
dylan604 wrote: post #127

Earlier quoted context omitted.

Brings a new meaning to "Charlie don't surf". At this point though, you have to pretty much imagine that the military has researched any and every mode/method/means of achieving the goals of a mission. I'm sure roller blades and skateboards have been considered at some point as well.

Not sure about the military, but French police has been using rollerblades to patrol the streets of Paris.

Taliban rollerbladers:

https://nypost.com/2023/11/15/news/taliban-seen-patrolling-k...

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#188

Post by dyauspitr »

sandworm101 wrote: post #42
willcipriano wrote: post #36

Earlier quoted context omitted.

Traveling at that speed for a long distance would be beyond human capabilities, wouldn't it? Super just means beyond, not way beyond. I blame Superman for this notion.

Not really. Most serious lap swimmers can do a kilometer every 20 minutes sustainably, akin to a marathon runner's pace (Sprint pace would be 100m/minute, with 50m/minute being what you would see in the fast lane of most recreational pools). So 3.6 kph isn't all that different, maybe a little faster than average but I assume they were also using a better-than-average bicycle person when doing the test. There real adv…

A mid tier marathon runner can do a mile every 20 mins, not a kilometer. It’s a significant difference.

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#189

Post by freeqaz »

pge wrote: post #93
wood_spirit wrote: post #83

It’s obscure but there was such a contraption trialled by the seals and cia in the 1950s http://www.hisutton.com/CIA_Water-Air_1958.html Here’s a pedal powered smuggling submarine from the 1940s http://www.hisutton.com/Swiss-Pedal-Powered-Smuggling-Submar...

Interesting that the CIA conclusion for a device very similar to the article is "Not recommended for operational use due to its discomfort and very slight gain in speed over that of a swimmer equipped with fins."

Toss a battery on it though and what does it look like then? Perhaps you're able to augment a human's ability to traverse longer distances more quickly. That's tech that didn't really exist back then!

Re: 'Underwater bicycle' propels swimmers forward at superhuman speed

#190

Post by schiffern »

RajT88 wrote: post #160
gnicholas wrote: post #158

Earlier quoted context omitted.

Sure, but a person paddling isn't hydrofoiling, right? They're using their arms instead of legs and contending with tons of additional friction/drag. I see this as being akin to bicycling, since it uses the same muscles.

Here's what I am getting at... https://youtu.be/SDX3Hz2gsas A guy on one of these doing the minimum speed. He doesn't look like he's casually pedaling, no? It's probably harder to maintain 6mph than you might think.

  >A guy on one of these doing the minimum speed.
Counterintuitively, that probably makes it harder.

With any wing, the faster you go in level flight the less drag is caused by lift. This strange fact is because moving a large amount of fluid slowly is more efficient than moving a small amount of fluid fast, and a faster wing can interact with more fluid mass per second ("m dot").

https://en.wikipedia.org/wiki/Lift-induced_drag#Calculation_...

Since skin drag increases with speed, adding these two drag curves together forms a 'valley' in the overall speed-vs-drag curve. Going slower or faster than this ideal speed will result in increased energy per mile.

The math is better explained in David MacKay's brilliant ebook, 'Sustainable Energy Without the Hot Air.'

https://www.withouthotair.com/cC/page_269.shtml

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