Yes, of course there are.
Vents on Jet Fins?
- Thread starter Eric Sedletzky
- Start date
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Put my "Editor's Choice award winning"
Tusa Hyflex fins on the shelf after seeing how much more power a jet-style yielded. I use F1s or Eddys depending on the trim demand.
Bob DBF
Contributor
Pretty much from before I bought my Farafins and after they wore out and were no longer available.
Mine was like the lower style, but was the length of the upper fin, as the leg braces were not available until after I purchased mine. They were the first spring strap, and built in to boot. Of course you needed strong legs to kick them, so they didn't catch on, even with the leg braces. Damn I miss those fins.
OP
Eric Sedletzky
Contributor
Those are great looking fins man!Pretty much from before I bought my Farafins and after they wore out and were no longer available.
Mine was like the lower style, but was the length of the upper fin, as the leg braces were not available until after I purchased mine. They were the first spring strap, and built in to boot. Of course you needed strong legs to kick them, so they didn't catch on, even with the leg braces. Damn I miss those fins.
I like the ribs in the middle, looks like they would grab water and keep the fins lined up good and add some strength.
Why did they stop making those?
Bob DBF
Contributor
Took over 20 years of North Coast diving, Ab and SCUBA, to wear them out. The leg power to use them was significant, jets were nothing after using them, the lower set in the picture were about the size of XL jets. When freediving, I could be vertical on the surface and kick to hold myself out of the water to the waist for a while, until my legs gave out. Power when you needed it, and they saved my sorry ass more than once in the surge.
I suppose I could build another pair out of plywood, or stainless, did I say they were heavy and stiff, but I don't have the strength I had in my 30's.
[HIJACK]Pretty much from before I bought my Farafins and after they wore out and were no longer available.
Mine was like the lower style, but was the length of the upper fin, as the leg braces were not available until after I purchased mine. They were the first spring strap, and built in to boot. Of course you needed strong legs to kick them, so they didn't catch on, even with the leg braces. Damn I miss those fins.
Interesting. I can't see this (and some other) pics when using my usual browser (Firefox running on MacOS). However, I can see it just fine if I use Chrome (on MacOS)!
[/HIJACK]
Hatul
Contributor
I think the idea is that the vents are shaped such that water going through the vents is sent back and so helping drive the diver forward. That's the theory anyway. There are lots of fins with holes in the blades closer to the foot, including the common Scubapro Nova. The idea is that its more efficient to push water farther from the foot from a flexed blade, which makes sense as the water driven closer to the foot is partly pushed down (or sideways in frog kick) which does not contribute to propulsion. Water pushed by the flexed blade is more directed back pushing the diver forward.
OP
Eric Sedletzky
Contributor
The idea that water being pushed down by the fin closer to the foot is sound. However, by not making an exaggerated movement with the kick would minimize this. The most acceleration I get using Jets doing a flutter kick is by mostly just using the tips of the fins and not moving my legs that much, more minimally from the hip. The increase in speed comes from flipping the feet/fins faster not harder with a wider stroke. Freediving fins work differently. They look more like a snake or an alligators tail when you view the legs and the fin do their work together. The fins are long and flexible and become an extension of the leg more than shorter scuba fins do.
I’m thinking that the “jet” holes are an outdated technology that was even questionable at the time they were developed. In order for any “jet” effect to happen, if indeed there is any such effect, the fin would have to be kicked really hard and water would have to be somehow accelerated through these vents to provide any thrust. At that point the fin has been overkicked and the work effort has surpassed any benefit that some jet effect would produce. So I’m calling bunk.
Do you find that the RK3 HD aren’t too negative for single cylinder?
I am trying to find a more positive fin for my JJ but that is still a bit stiff.
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