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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

#281

Post by samplatt »

nurple wrote: post #210
user20180120 wrote: post #194

Would this device be even better if it has the newer efficient propeller design called MX-1 Sharrow Propeller ? https://www.boatus.com/expert-advice/expert-advice-archive/2... At the 2020 Miami International Boat Show, Philadelphia-based Sharrow Marine introduced the culmination of a seven-year research and development project called the MX-1 Sharrow Propeller. Unlike every prop that's come before it, rather than bla…

I think for water, what you really want is to _breed_ cavitation, but in a way where the jets created by bubble collapse are arranged to face opposite your desired direction of motion. Kind of like Astrophage.

Cavitation for motorised propellors is to be avoided at all cost... a lot of engineering exists to do exactly this.

Cavitation is a destructive force and eats away at the edge & surface of the prop blades, making it VERY inefficient.

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

#282

Post by julianeon »

SOLAR_FIELDS wrote: post #257
ben7799 wrote: post #106

Earlier quoted context omitted.

You just need to get familiar with the correct way to handle a current like that. It’s not to fight it. Especially with a bodyboard and fins doing the right thing does not require a ton of strength and shouldn’t be stressful.

Your comment kind of implies that a strong swimmer with a surfboard and the right knowledge will pretty much never be in a situation where a riptide/undertow/current/ whatever you call it carries them out too far to swim back. Is that true? (It might be, I just know very little about surfing)

This article about my beach makes it sound like, if the waves are big enough, all bets are off. Note: it's about a surfer who died, but I'm focusing on the comments of the surfers they interviewed.

https://www.sfgate.com/bayarea/article/san-francisco-surfer-...

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

#284

Post by vitiral »

simonbarker87 wrote: post #48
vitiral wrote: post #37

Earlier quoted context omitted.

Really, why? Because you might drown? Try holding your breath and just floating, arms at your side and legs not moving. You will bob to the surface. Then quickly release your breath and snap your neck back to take a new one. Repeat. That's all it takes to not drown. You could almost do it as a quadriplegic (though I'm not 100% on "water balance" in that case).

Some people (myself included) don’t float like this. I try basically every time I get in the water and my legs drift down to just after 45 degrees and then I slip under completely and don’t resurface until I give in and swim back up. People who can float never believe me, but enough have now seen me in the water that I know I’m not “doing it wrong” I just don’t float. The people who’ve seen me try it in water always…

You are talking about floating on your back. I'm talking about bobbing. As long as you hold your breath, your head will be under the surface... Unless you're built like a brick I guess.

But a brick with lungs. Hold full breath. If even that doesn't work then I guess swallow air and try not to burp or fart?

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

#285

Post by hackable_sand »

password54321 wrote: post #270
hackable_sand wrote: post #214

Earlier quoted context omitted.

Wait until they hear about wheelchair basketball.

I remember reading Surely You're Joking Mr Feynman and how he described back then how the world is full of dumb smart-alec and I get reminded how that still holds true.

Yuuuup. No need to waste the good ammo when you have cheap, dumb, and reliable.
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