Jet Fin vs Rocket Fin

[stevestevekp]

hi sorry.. has any of you heard of saekodive fins? link is ( saekodive.com.tw/showpd.php?pdid=5972&catno=6&catname=Fins&subcatno =0&subcatname=" )...

i am considering buying XS power, till i chance upon this brand... or should i just stick to xs power?

 

[foxgolf]

I have both of them and compared them.
Althought Rocket Fins are stiffer but they're much shorter than Jet Fins and have bigger vent with right angle make it easier to kick down than Jet Fins. As you notice the big vents have the right angle to make the water flow easier when you kick down make you less tired. Plus the big water channel enable your feet to kick straight down and not wobbly like the plain Jet Fins that can hurt your knee. And this rigid Rocket Fins are the best for frog kicking.

It is often my belief that people confuse these two fins. I hear it all the time, I used those once and they were too stiff, stiff as boards etc and recently it comes up again. Rocket Fins are not deserving of the name at all and they are among the worst fins ever made whereas the Jet Fin is among the very best if not the best and the choice of serious divers the world over for four decades. Here are a few pictures, first a comparison of the one size fits all USD Rocket Fin circa 1975ish vs ScubaPro Super Jet XL circa 1978ish:

As you can see, they really do not look alike at all and the vents on the Rocket are upside down!

Ok, stiffness, no, no, no, the Jet Fin is not a stiff fin, that is why they work so well and are so completely different from the Rocket which is in fact, stiff as a 2X4. First is a picture of the Jet Fin hanging under it's own weight at about 1/3 blade:

Now a picture of a Rocket Fin hanging on it's own weight, again about 1/3 of the blade:

Having used both fins extensively, these are MY fins BTW, I have owned them since new, the Jet Fin is not a stiff fin and is nothing like the Rocket fin in any way other than some distant similarity in terms of shape when viewed from about 100 yards. Not the same fin at all in any way .

Jet Fins, over and over, in swim tests against virtually every type of fin come out on top or at the top, they are the universal, do everything well fin for scuba divers. The Jet has the perfect blend of stiffness, a supple blade to allow fine control and effortless speed and plenty of backbone down near the foot pocket for digging in under heavy load as in swimming a scuba diver against a current or frog kicking. The Jet will not fold up like so many fins when kicked hard or over kicked--if you can even over kick them--they just keep delivering thrust! The supple tip carries the energy of the kick through increasing the efficiency of the Jet. I know of no fin that combines the capabilities of the Jet. Some like the Quatrro are as powerful, some like the UDT frog kick as well, splits are as fast, FF are as maneuverable but NONE of them combine all of the attributes of top performance into one fin except for the ScubaPro Jet Fin, the choice of more serious divers the world over since the early 60s. The Jet Fin, then, now, thirty years from now it is highly unlikely it will be dethroned as the worlds best all around scuba diver flipper.

N

 

[trapezus]

​my Jet-Fins :

I always prefer Jet-Fin in my dives .

Jet-Fin Beuchat Espadon

 

[John C. Ratliff]

Foxglove,

I think you are comparing the Rocket fins with the Lightning Jet Fins, which are longer and have a better flexibility than the original Jet Fins by Scubapro. I have never used the Beuchat Jet Fins (which I think were the original, originals).

SeaRat

 

[danvolker]

I wasn't going to post on this thread about Freediving fin superiority over Jet, until I saw so many posts claiming that jets are the best fin there is....
The truth, which is easy to demonstrate, is that the jets are very inefficient fins compared to the vastly superior technologies of carbon fiber or composite freedive fins....which can allow a kick and glide to use either half the effort, or double the glide between kicks.....roughly.

And then so many will say, fine, but I wont use freediving fins, they are too big on the boat, etc., etc.... And in truth, if you are doing penetration diving with a close/tight overhead ceiling the fin tips could scrape, then the freedive fins are the wrong fins......BUT...there is still a choice for a fin actually slightly shorter than Jets, with FAR MORE advanced technology and efficiency...and this is Force Fins....Specifically, the Extra Force or the Excellerating Force models are the ones I would put up against the Jets....

In this contest, there is one area the jets will win in....If you are having a race on the bottom, over a muck bottom and you need to be close to the bottom...you need to frogkick...then the slightly larger blade of the jet fin, as stiff as it is, will push a little more water per kick cycle...per push, than the Extra Force or the Excellerating Force--because the blade areas are not quite as large....However, most of the divers I know that choose to do frogkick all the time, don't want to race, so the speed difference here is really moot for most divers...and over muck bottoms, high speed is not usually on the agenda--precision and no silting, is--and the Force fins shine much brighter here than do the jets......

And....When speed is important....when you have to go upcurrent to an anchor line, or get to a buddy in an emergency, or get a video of a manta ray or whaleshark or other marine life that is swimming at 3 to 4 mph...the problem with the jets is that they are ok for flutter kick, only up to a certain effort level, and then they become very inefficient....Take even a competitive track cyclist with legs three times the size of a normal diver's, and once you get to the power levels needed to hit high speeds for a diver, they begin to cause major lactic acid buildup in the quadriceps. They Sprint, inefficiently....but you can't sustain a sprint for a long time....Now most "floppy dive fins" really sprint poorly, and for this reason, a jet fin wearing diver may think they have better fins...because they can do a real sprint...they dont just over-kick the jet fins fins like they would most brands sold to scuba divers.

Also, the Jet fins require a very "easy to acquire" kick shape, almost intuitive. This is fortunate, because very few instructors will teach optimal kick shape to their students...and each type of fin, will often have it's own unique optimal kick shape---don't use the optimal kick shape for the fin, and you risk losing most of or all of the technology advantages--ending up with a fin that wont do what you want it to....like a snow skier that has a hard time turning a new pair of high performance skis with the technique he is using.
The 2 force fin models I mentioned, have a radically improved high speed efficiency for flutter kick ( with medium or long duration), far beyond anything possible in jet fins. Force fins sprint well too, reaching amazing speeds. But ten second long sprints are often not going to get the job done...you may often need a minute, maybe even 2 or more for the critical event. This is where the Extra Force really slams the jets.


ON THE OTHER HAND....If you get a pair of these Force fins, you do need to alter your kick shape....Some divers that do lots of leg coordination sports, will feel this shape within a dive or two...many other may need to have this kick shape shown to them..and then in as little as 20 minutes to an hour of using this, it becomes natural, and new Force fin user will NEVER consider going back to the inefficiency of the tired old technology of the jet fins.

When I say kick shape, it is the amount of knee bend, the amount of hip and back involvement, the amount of articulation of the ankles--and where this occurs in the kick cycle, it is how large the amplitude of the kick , and how fast the kick cycle or cadence is.....there is a very definite sweet spot for most fins.

I can show this to anyone at the BHB Marine park....and I have Jetfins and Force Fins and DiveR freedive fins and many other brands I can let anyone try, to illustrate the point...And I can shoot video of the proof
Attached image is a pair of Extra Force Fins.... Among the better technological advancements over the jets, the 2 Whiskers you see on the top surface of the fin in the photo, do little when you are just taking it easy..but if you have a speed emergency, as the kick drives the fin in the downward path harder, the increased flow pushes through the two whiskers, and a powerful FUNNEL EFFECT occurs-- which feels like suddenly the fin has twice the length (or push) than it had before this funneling effect, and it acts like a turbo charger ---it seems to actually INCREASE efficiency with higher speeds, becoming more like a freediving fin--though it does require a higher cadence than a freediving fin does....and this allows the diver to drive the high speed effort more with aerobic power-for very extended periods of time if necessary..... RATHER than force them to drive this with ANAEROBIC POWER as would be happening with the jet fins, which are limited to a relatively short sprint.

The material the Force Fins are made of is also dramatically higher tech than the jet fin rubber ...Meaning better flex characteristics, that more closely match the needs of the diver and the kick shape being used.



With all that being said, I still prefer steel 72's to Al 80's by a wide margin......I would be quite happy doing recreational dives( 90% of what I dive these days), with a j valve and a single reg ( which is easy to buddy breathe with for any dive buddy I would have), and I could pretty much be living in 1960's gear, all except for the fins.....When I was certified in 1972, I was always looking for the most powerful fins....this led me to the Farrah Fins with the ankle brace( because they were insanely stiff and long) as soon as they came out. These were pretty much Jet Fins on Anabolic Steroids AND Growth Hormones
In fact, the only time they would really flex, was when you were involved in a full tilt sprint The rest of the time they were boards...long ones. At some point in the 80's I realized efficiency was a bigger issue, to accomplish many of the adventures we were after at the time....This was at a time when I was trying to get into structures and high current sites, or deep and fabled sites related in fisherman's stories, etc....to go "where no man had gone before" So the need for a quantum jump in fin technology first pushed me to the Cressi Rondine Garas, when they came out, and this one area of dive gear technology, our ability to move ourselves around well underwater, to me should not be compromised by defective technology....the old steel 72's, the masks, the regs, the harness without BC, all this allowed you to do ANYTHING the 2014 advertised equivalent would do.....Not so with fins.

 

[David Wilson]

Foxglove,

I think you are comparing the Rocket fins with the Lightning Jet Fins, which are longer and have a better flexibility than the original Jet Fins by Scubapro. I have never used the Beuchat Jet Fins (which I think were the original, originals).

SeaRat

Indeed they were, John. Here is an early flyer for Jetfins published by Beuchat of Marseilles:

In the 1960s, when Jetfins were first designed, European divers preferred using full-foot fins. When I learned to dive back then in England, we were encouraged to purchase two pairs of full-foots, one normal-sized for the pool, the other one size larger for open-water use. The smaller-sized Beuchat Jetfins were full foot fitting ("chaussant" in French). The largest-size Jetfins were open-heel, however, the argument being that a full-foot version would have been very expensive in that size. In Europe, at least, full-foots cost much more than open-heels during the 1960s. When Scubapro bought out Beuchat's invention, the American company never brought out a full-foot version of their Jet Fins.

One version of Beuchat's full-foot Jetfins came with a heelstrap. This design lives on in Turkey, where one Istanbul manufacturer, Adalilar Kauçuk, sells its own version of the Jet:

 

[John C. Ratliff]

DanVolker,

Actually, this is a Jet Fin vs Rocket Fin thread. But since you brought up other fins, I have a few observations. I have talked extensively with Bob Evans, who invented the Force Fins. I have found advantages, and disadvantages. Here is a description I wrote some years ago:

(...it's after supper.)

During supper, I re-read a chapter that Fred Roberts wrote in Basic Scuba titled "Swim Fin Analysis, Addendum to Chapter 9." In it he gives one of the best descriptions of vector analysis of swim fins that I've seen written anywhere. That is probably the engineer in him coming out. I also looked again at both the Duck Feet fins that I have and the Force Fin. This gave me insights into the physics of swim fins that may be helpful in describing what the Force Fin does. I'll await another time to do that analysis though, but did confirm that the Force Fin bending occurs behind the toes (toward the ankle), and not in front of the toes as in most fins.


As I said above, I have now done five scuba dives with Force Fins, four in the Clackamas River and one in the Columbia River. The last, in the Columbia River, was just a day ago. It was during the noon hour, and only 15 minutes long off a sandy beach into about 10 feet of water and a mud bottom. I saw some interesting close-ups of tiny tube worms, and a bivalve mollusk, but not much else. However, my fourth dive in the Clackamas River was after work last week, and I had forgotten my wet suit top. So I dove in only my swim suit and a T-shirt (67 degree water, and I have enough blubber of a 1/2 hour dive). But the other thing I forgot was my booties. So I dove the Force Fins with an old half-foot sock I cut from my worn-out booties. During the dive I again pursued fish, and caught up with a few too. I talked down to the river barefoot, put the fins on, and commenced with a half-hour dive. My exit spot was downstream, and consisted of climbing out of the river at a small park. The river bank was rocks, and the climb was about twenty-five feet vertical to the grass, then the rest of the way walking up a bike path to my car. Well, I was not too sure about doing this barefoot, so I decided to see how the Force Fin would do on land. I was able to climb up some rather steep areas, with small foot holds, with the Force Fins still on! I would not have even attempted this with any other fin, especially with the webbing on my scoop fin design. These other fins only negotiate land backwards. But I walked clear to my car (over 100 yards, and probably forty vertical feet) with the Force Fins on. My feet, well protected, approved.


I'll write some more over the weekend on what I see as the physics of the Force Fins, which may look a bit different from what Bob has discussed before. But one part of these fins is undisputed--that I can walk on land with them.


SeaRat

I have done extensive fin analysis, and the Force Fin required a much different kick to be effective, as it is designed to produce force backward mostly on the downstroke, and use the upstroke as a resting stroke. While they are effective, it takes a bit of time to get used to them.

I dive almost exclusively my own design (see the photos), which I call the "scoop fin." It has advantages over the regular fins, and Jet Fins, and actually the Force Fins. I have used them out of helicopters and with parascuba jumps in the 1970s, and no manufacturer has come up with an equivalent (though MARS tried, but didn't get it completely correct). They work on both the downstroke and the upstroke, and effectively funnel water back to provide thrust.

Getting back to Jet Fins vs Rocket Fins, they in their original forms were pretty much equivalent. The vent vs the slot was a non-factor, they both factored about the same in reality. The slot says it propels water backwards on the downstroke, while the vent only dissipates water in a dead area of the fin on the downstroke. The slot (Jet Fins) doesn't work on the upstroke, whereas the vent (Rocket Fins) works on both the upstroke and downstroke.

SeaRat

 

[danvolker]

DanVolker,


I dive almost exclusively my own design (see the photos), which I call the "scoop fin." It has advantages over the regular fins, and Jet Fins, and actually the Force Fins. I have used them out of helicopters and with parascuba jumps in the 1970s, and no manufacturer has come up with an equivalent (though MARS tried, but didn't get it completely correct). They work on both the downstroke and the upstroke, and effectively funnel water back to provide thrust.

Getting back to Jet Fins vs Rocket Fins, they in their original forms were pretty much equivalent. The vent vs the slot was a non-factor, they both factored about the same in reality. The slot says it propels water backwards on the downstroke, while the vent only dissipates water in a dead area of the fin on the downstroke. The slot (Jet Fins) doesn't work on the upstroke, whereas the vent (Rocket Fins) works on both the upstroke and downstroke.

SeaRat

Would like to see your fins some day !!
And, the Dive R Freediving fins provide HUGE thrust on BOTH up kick and down kick. If you want to go ridiculously fast, and you have the power ( like a cyclist would), you change gears essentially at what is a high speed, and change kick shape to an oscillating low amplitude high frequency kick, not driven by quads but rather calves/ankle articulation, and some hip and back muscles.....the composite fins describe an amazingly fast oscillation, and I can use this to keep up with many fish that travel at speeds far beyond what scuba divers can handle. I once stayed with a foraging pod of 25 to 35 Bottlenose dolphins, over a reef line for half an hour.....pulled by a big Gavin scooter, and doing the fin oscillation to boost the speed of the Gavin to fast enough to keep pace with the 5 mph or so minimum speed of the bottlenose when foraging. I have the video to prove it

 

[Eric Sedletzky]

I'm another user of freediving fins on scuba. I use them for high speed pursuits and covering a lot of ground (hunting).
They burn more gas but the speed and power is unequalled. To make up for burning more gas I outfitted myself with a bigger gas tank.
My jets can't come close to the top speeds I can reach using freediving fins, but for slow diving I can make jets do some amazing things by just twitching my feet around certain ways. I don't worry about anti silting techniques because there is no silt where I dive.
I also have turtles which are shorter and wider than jets and the vents are slightly different. The only problem with those are the foot pocket is huge and they flop around on my feet somewhat taking away movements to the actual fin.
I also have a pair of quattros which are OK, but the flip flopping of the water channelling flap on the end makes it not ideal for face down surface swims because there is some wasted movement past TDC where the baffle/flap moves back and forth. So this makes me have to move my leg further out of the slipstream to get any "traction" which isn't an issue with either freediving fins or jets.

Freediving fins are actually pretty hard to compare with other fins because they wouldn't be used for the same kind of diving generally, and because the dynamics are completely different.
99% of todays standard recreational divers wouldn't be able to use freediving fins just based on how the rest of their gear is configured.
To be effective with freediving fins, first you have to be in shape for them, and second your gear has to be minimized in drag/slipstream for the full benefits to be fully realized, which is in stark contrast to todays Jacket BC's and cluttery configurations i.e. hoses sticking out everywhere, large puffy overstuffed BC's, consoles dangling, pockets full of whatever they stuff into them, etc.

I guess it all just depends on what you are into. The important thing is to keep an open mind and consider what type of diving each fin is designed for. A blanket statement as to which fin is the best is as rediculous as making a claim as to which type vehicle is the best - how do you drive and where do you go?

 

[hedgehog47]

heres a good question, are you able to distinguish the jet fins from the rockets just by looking at them ? if so, how ? there's a few for sale on craigslist and i dont wanna get the other pair.

although i do love my force fins so I probably wont switch