The never-ending Jetfin debate...

[jplacson]

Ok, doing my own personal testing (very informal... don't take it seriously) with some friends... the classic Jets do perform better over-all than most, if not all, other fins.

Here's my question... it's pretty obvious why they work well... they're stiff, and have channel thrusts in the middle... although they seem to be optimized for the downstroke like most fins... I was wondering why they don't TRY optimizing for the upstroke...since the human leg is stronger on the downstroke, and weaker on the reverse, optimizing it for the upstroke would actually give you more consistent speed and acceleration...since power would be almost even on both up and downstroke.

And I know the 'frog' ends don't make the fins perform any better... so why don't they try re-styling the things???

Just wondering cuz these fins don't seem to want to go away... and that's fine...if it works, it works... but come on!!! They haven't even bothered changing the style AT ALL! Not even color accents, or something...ANYTHING!!! I mean...don't tell me that by now, they haven't found even a better way to angle the channel thrusts??? Something to make it look a bit modern?

Anyway.. another question, this time to Mares Quattro owners... how does the Quattro perform using alternate kicks? I did some research on the net and so far, the Quattros seem to be lagging just a little behind the Jets when doing the frogkicks.

 

[Walter]

You are mistaken. Rubber compostion was changed in the early 1980's. Lightning Jet Fins are the result. The change in rubber compostion improved their performance.

In the late 1980's or early 1990's the introduced Jets in pink, yellow and blue in addition to the normal black. They didn't sell that well.

"And I know the 'frog' ends don't make the fins perform any better... so why don't they try re-styling the things???"

How do you know?

 

[jplacson]

:lol:

Ok, so they changed the rubber...

and attempted to sell ugly colors (I'm assuming the colors you mentioned were the entire fin, and not just accents)

Regarding the frod looking ends... cuz a friend of mine a while back shaved it off (dunno why) to make it a concave arc... instead of the semi 3-point it really is... and it didn't really affect the thrust noticably.

Anyway, I was just wondering... I mean... since they were originally SP Jets... fine. But other manufacturers don't even try to improve on its design.

I've seen something similar on a Beuchat pair... but they used soft plastic.

I'm just curious why we haven't seen 101 variations or improvements of the Jetfin from other manufacturers... granted I've seen those central channels on 'low end' plastic fin designs... but nothing in the higher end line made of rubber... or some other compound.

I've seen more variations of the split fin than the Jets... sorry... I'm not against Jets... I'd just like to see more variation than the ones we have now... they don't even bother to sell them with spring straps as standard.

 

[Walter]

I don't think it would be possible to improve them.

 

[Kevin R]

It's the same shape has been used since day one, maybe it's because they don't want/need to change the moulds or tooling. I think it's a limited market that may be slowly growing so others are not yet willing to jump on the bandwagon. I did notice that Aqualung is selling rocket fins again.

I find the fins work best with the frogkick. Oh yeah, it raises less silt too.

The soft plstic fins aren't as good when doing the modified frog in tight areas or the reverse frog to back up.

I could have had these in pink???? Man would Andrew G. have loved that on my Tech II. Just think how well the blue fins would go with the blue panels on the sides of my pioneer wing.

Kevin

 

[jplacson]

Thanks Kevin! I understand about the market... they could've at least included spring straps as standard already..since people who buy Jets replace them anyway.

So do the Jets perform better in a frog kick than a normal flutter?

 

[SeaJay]

...And I can give you a pretty good "lowdown" on the difference between the Jets and the Quattros...

By comparison of the Jets, the Quattros are about 2" longer and about 1.5" narrower. They are made mostly of plastic rather than rubber, which means that they aren't nearly as negative in the water.

...Which is a characteristic of the Jet fin which is truly beneficial, yet often overlooked. A correctly trimmed diver can adjust his body attitude in the water with a Jetfin... But must kick the Quattros to adjust attitude.

Imagine you're just floating there... Horizontally, and in the skydiver position. With the Jets, if you bend your knees, you'll go head-down. If you straighten your leg, you'll go head-up. The difference isn't much, but it's there... So the Jets have a serious advantage in control over the Quattros, especially for someone diving caves or wrecks where a kick might stir up silt.

Of course, if you do choose the Quattros, you can "fix" the weighting problem with some ankle weights, but that's sorta "putting a band-aid on it" if ya know what I mean.

Additionally, as you've mentioned, the Jets are much stiffer, making for precision kicks - at least much moreso than the floppy Quattros. Since they're shorter, too, they're easier to judge and retain control over the tips.

Lastly, the width of the fin actually means that there's more surface to the fin than with the Quattros (actually depending on size, but that's another issue). Frankly, I've found the Jets to be considerably more efficient at getting power to the water.

The only downside I can see is that they're so stiff that kicking a normal flutter kick is so powerful that it can tire you out pretty quickly. People not used to them complain of muscle strain and cramping. Quattros, as with many other soft fins, bend so much that they're sorta like pedaling a bicycle in a lower gear.

Anyway, your question was about alternate kicks... Yes, the Quattros do very well for alternate kicks. Frogging works well, and I'm even able to backwards kick in mine... Although it's much easier and more precise with the stiffer Jet. With my Quattros, I almost have to do these kicks in slow-mo in order to ensure that the fin doesn't "flop" and make my fin stroke worthless. Backwards kicks in the Quattros take a lot more ankle motion than the Jets in order to get them to work. This is because of the "floppiness" of the blade.

I once tried an interesting test... You decide on the validity: I put a Jet on one foot and a Quattro on the other and did a "standard" flutter kick underwater in zero vis in order to obscure direction. I swam in what I thought was a straight line; I applied the same amount of power to each fin to see if more power was produced with one fin or the other. I was floored to find that I went around in circles... Much to the favor of the Jet fin. It was like being in a higher gear with that fin.

There is one word of warning about the Jets, though... They simply don't fit everyone. The foot pocket is short and small, and I found them to be very uncomfortable. To me, this was enough of a reason why not to keep them, but I'm eagerly awaiting the new design (foot pocket) that's due out in the next couple of months. Additionally, I've found that selecting the right bootie for the Jets could solve the problem. Quattros... Well... They seem to fit everyone and are super-comfortable.

No doubt I'll be switching to the Jets soon... In fact, I'm dying to do the switch now. But I need to find the right combination of bootie and foot pocket before making my purchase.

 

[Scubaroo]

SeaJay once bubbled...
...I'm eagerly awaiting the new design (foot pocket) that's due out in the next couple of months.

ScubaPro is coming out with a new foot pocket design? Do you have a reference, or is it rumor?

Interesting. I wrote to ScubaPro almost a year ago suggesting a new foot pocket design for the JetFin (aimed at drysuit divers - the pocket of the TwinJet fitted with the JetFin blade), and never even received an acknowledgement of my letter.

And here's me thinking I had achieved nothing more than crank-status

 

[SeaJay]

Sure, the "rumor" has been going around for a while now... But I got the info from the good people at Extreme Exposure, who told me that they'd heard it straight from the mouth of a Scubapro rep.

I'm with you on the footpocket of the Twinjet... I really like the longer bottom than top, and find that it braces against my foot better than the "bucket" design of the Jet. It simply provides for better leverage, IMHO.

That said, there's not many people who seem to have a problem with their current Jets. I truly feel that the difference lies in the booties. I wear "sock" type 3 mil booties... Those who dive Jets always seem to be wearing booties with a more significant sole. I believe that this allows them a little better fit to the Jets.

Unfortunately, if I go any thicker than a sock bootie, I can't get my foot in the pocket of the Jets at all.

Interestingly, Walter showed me HIS Jets last weekend at Ginnie... And they seemed to fit well, with enough room for a thicker sole. I am now truly confused. For reference, I did stop by EE again to try on the Scubapro Jets in their largest size one more time... There seems to be a difference in pocket sizes from fin to fin!

When I asked about the foot pocket rumor, they ensured me that the larger foot pocket is supposed to be out in "the next few months." What I've heard is that it's simply supposed to be larger... To cater to the drysuit crowd. I understand that it's supposed to be Turtle-category, which are entirely too large for my wetsuit booties, even with a thick sole (I can't win).

It's my sincere hope that they're coming with a Twinjet-type foot pocket that's sized between their current XL and the Turtle foot pocket.

...Maybe I should ask Walter where he got his? Maybe he's got a set of the rumored "military" Jets that supposedly had a slightly larger foot pocket...

 

[Scubaroo]

I wonder if the new fin mentioned at EE is different to the supposed Navy "XXL" JetFin.