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Weird fin from long ago

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Well-Known Member
Oct 28, 2001
There's a saying: "Everything that's old is new again."

A couple of years ago someone posted a hand drawing of a wing-like fin that is positioned forward, ~waist-level of the body, and uses the larger muscle groups (quads, gluts) to work it. It's a rather unique concept from the olden days (the '70s) and I'm sure everyone here is always on the look for a way to squeeze out that last bit of efficiency.

I've finally found the patent for it after digging around and am posting it here for the more mechanicallyintrepid amongst us.

Who wants to dive with one? Better yet, who wants to build one??:D

Peter S.


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Thanks Peter
That was some research job that you pulled off. My drawing wasn't too far off, but the inventor's name seems a little different. Sure wish that I had put it in a box and saved it. I think the commercial name was Aqueon. Now I wonder if it was as efficient as I remember.
Aloha, Mahalo
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I don't know if it would have been efficient but it looks cool ! :D
Would love to have a go on one. Bill are you saying you had one ?
I'm still waiting for someone to come up with a device that has bicycle pedals and uses a propeller for propulsion. :D

That idea of a prop and pedals could be fun to build but I might give it a go with hand cranks instead so that old guys with bad hips can use it!!

Darn Ausi's. They keep picking on me.
I talked about pedal power with an engineer that built a few of those bicycle/canoe combos that can go 50% faster than Olympic kayaks, but when they tried a 'submarine' version, he said there was too much drag from bending the knees.
Back in the early 70's I bought one of the devices that Peter tracked down the patent on. The thing was hard to steer, but maybe no worse than a monofin. Diving in the kelp was impossible, but in a straight line, you could really get it moving fast. I lost it before I got used to it. The inventor did have the results of a test. I think it was a one mile straight run on scuba, he used 25% of the air that the navy diver used with jet fins and he was an old guy, in his forties.
By the way, we now have a very nice clean rope in 64 meters after two Sundays work by Matt, Leo and Carlos. I had the easy job of watching Annabel doing froggies.
Originally posted by Bill
My drawing wasn't too far off...

Was it you who posted the drawing, Bill? Hm. I still can't find it in DB's forum archives. That's why I went straight to the patent database...

Doug Peterson said he still has a picture of it in an old Skindiver magazine. I'd like to see that. I think that with a little modern updating, composite instead of fabric cover foil, a little swept angle for a little dynamic stability, etc. etc., this is one of those wacky ideas that may actually improve on the good ol' monofin.

Peter S.
The Aqueon - that's the name. Thanks Bill, now I can troll Ebay for any that will pop up!

Peter S.


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> this is one of those wacky ideas that may actually improve on the good ol' >monofin

I've been thinking about that for a while. The biggest advantage is that you don't have to change your stroke on the surface. There is no way to get the foil out of the water and you don't lose half your stroke as you do with the mono. I think that the rigid foil has a lot less drag than any flexible fin. Eliminating the foot pockets and strapping it to the shins was a good idea, too. I spent about thirty minutes with the inventor and I think his IQ was about double mine, maybe 150 or so.
Thanks for the picture. I never saw or met anyone else that tried it.
Technically it would be legal in current AIDA rules, although there is a dumb clause in the rules that give the judges VETO power over anything 'new' which they think is unfair. Once again, discouraging innovation.

I'd like to try to build this wing device.... think there is a market for it?

Eric Fattah
BC, Canada
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Personally I'd allow the use of the Aqueon just to see people's jaws drop at someone doing a 250m dynamic with it and everyone else crying foul. But that's just me. :)

Judging by the number of downloads of the patent so far (89 times), I'd say you have a market for it - competiton too, including me! ;)

Peter S.
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Here are a couple of interesting links about the Aqueon I dug up. There is a video link in the first one, but I couln't get it to work correctly. Perhaps a more familiar RealPlayer user can look at it and let us know if it's worth messing with. The second is a narrative of the '96 World Sub International. These are the folks that build man-powered subs FYI. At the end it appears that the inventor Calvin (supposedly 80 at the time) jumped in and demo'd the Aqueon.

Aqueon in action!

World Sub International - 1996

Towards the end the author says that Calvin originally marketed the Aqueon to scuba users but didn't have any success in that market. I can see why - the limited manueverability of this item makes it difficult to use up close and personal to the bottom. The same reasons that monofins really haven't caught on for the scuba users. Not to mention the movements are difficult when strapped to a 100 cubic liter tank. :t And I don't even want to think about trying to explain this contraption to the security folks in the airport.

I think one of the biggest advantages that this invention has is the ability to vary the angle of attack on the main fin. All of the aquatic mammals have this capability via a joint at the base of their fins. This allows a much more efficient swim stroke as the change in the angle of attack decreases drag through the water as well as forcing more water backwards rather than up or down. Look at any video of mamals in the water from a side view and you can see this appearant this adaptation is.

Mammals in action!! Belugacam!

I think this is also what enables the reduction in fin size/shape to something more hydronamically feasable. If you look at the ratio of body size to fin size you see that the human with a mono is WAY out of whack when compared to other aquatics. I believe that the way we have compensated for the inefficiency in not being able to modulate the angle of attack is by upping the size of the fin surface. And while we are pushing more water backwards (more speed) we are also pushing a lot more up and down (wasted energy) and creating a lot of drag (fin is WAY too big). If you go outside the aquatic mammals and look at tuna or shark fins, you see that big fins are not required to produce large amounts of speed or power efficiently.

The variable angle of attack is what I think the next great revolution in monofin design will hinge on. A couple of things to note. Calvin has recaptured some of the wasted energy of the stroke through the efficient use of a spring. While I think this is a good engineering fix (you can tighten and loosen the spring for different users strength) I don't think that this would ever be allowed in AIDA competition for the same reason a pedal powered propeller would be disqualified. Too much mechanical aid to the human. I am not sure that I entirely disagree......part of what makes freediving so addictive is the feeling of freedom and naturality it seems to impart. Semantics? Maybe.......I know I freedive with long fins and goggles.......but there is some indefinable "unnatural" line you cross when you put my bicycle in the water and I ride it around. :t Secondly, if AIDA can't unanimously endorse Liquid Goggles (a product that is so awesome, easy, and FUN to use that it is mind boggling that EVERYONE doesn't have a set just to play or set records with because you don't have to equalize your mask) then there is no way in H - E - double hockeysticks that they are gonna approve of this.

I know that we try to recoup some of the lost energy of the monofin stroke through materials that rebound - like fiberglass. I think that if someone could make a springy fin that attatched to your shins (similar to the way the Aqueon attatches) and allowed the fin to change it's angle of attack throughout the finstroke with something like a hinge you would see some new records being set. If you could use strips of fiberglass along the hinge to recapture some of the stroke energy it would be even better. And as long as you didn't change the overall profile of the fin it may just be possible to get it approved - although of the entire process, this is imho the sketchiest part of the plan. I don't think that placing the fin in the middle of the body would be accepted. As Eric F can attest, most people are not open to change, even when it makes the most sense in the world to do so.

Sorry for rambling......this topic is somewhat of a passion of mine.:eek: Oh and if you look at nothing else in this post, check out the beluga cam. I have it in a little frame on my desktop just so I can watch the belugas and destress while working.
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I remember looking at these things back in the day. I think then, no market - now with free-divng all the rage; why not!? Plus technology and materials improvements - could be really interesting to re-develop.
Aqueon for sale:

[ame=http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180532504596]Innerspace Corp. Aqueon underwater self-propulsion - eBay (item 180532504596 end time Jul-19-10 21:48:40 PDT)[/ame]
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