Force Fin review by a die hard Jet Fin user.

[Bob Evans]

Laurin, I have asked Blair Mott to link like crazy, I've learned a lot from his links like the one with Luke Clyburn from the Noble Odyssey Foundation. My Diving Hero says all " Mr. John Chatterton." Another LinkYouTube - John Chatterton Force Fins and SUDS

 

[meesier42]

I spend a lot more time underwater maneuvering myself precisely, than I do trying to generate tons of force -- the only place I've had to do that was in high-flow caves in Florida. To maneuver precisely in my Jets, I use my ankles and the muscles in my feet. I wonder how well this works with the foot pocket in the Force Fins -- DA, can you comment on that? We've kind of gotten focused on sheer power here, but there's a lot more to finning than that, even in caves.

With proper technique Force Fins are the only fins that I can swim sideways, couldn't tell you how I do it and its not fast, but when I am pushing my DSLR around its a great trick to keep the fish in frame. In caves and high silt environments just keeping my knees at 90 and using just my ankles to activate the blade. Forward, backward, sideways, rotation, helicopter turns, hell I have even turned the helicopter turn vertical just because I could.

The foot pocket allows better everything except tactical feedback. Your not going to feel the pressure of the blade against your feet, knees, hips, etc... your just going to feel yourself moving along. Its a very different sensation, but once you adapt, you feel freedom of movement and with the freedom you can move anywhere you want, anyway that you want. It takes time to overcome the conditioning that other fins have convinced you is how a good fin feels (terrestis fins), but once you gain the confidence to move in an aquatic world you'll be using fins that make thrust to propel you instead of drag.

 

[Bob Evans]

We had a great evening

 

[Blair Mott]

Laurin,
Thank you for your post and feedback. We are looking forward to making several additional videos to cover the points you have brought up and illustrate what you want would like to see.

We have lots of accomplished and competent divers using Force Fins all around the world in a variety of equipment configurations and diving conditions. Add to the fact that Force Fin has been around 30 plus years we understand the value of the Force Fin Product.
So on trying to “convince the crowd” we might present some of our information as “ You had to be there” or “ You will not believe it until you see it or do it”, but Force Fin is an Experience. The fins have an exclusive feel and design that changes the way water moves around your fins. You can not understand an experience with out having an experience.

I am looking forward to firing heavy artillery someday, but won’t know what it is like until I am on the range.
I have read and researched the Mercedes CL 65, but I never will know what it is like to drive it until I am behind the wheel.

My point is Force Fin has a 30 day policy. We want our customers to use the Force Fin products in the water as much as possible for 30 days. For some this means 3 weekends of diving. Some customer more, some less. If not satisfied, if you want to try another size or wish 100% finical investment returned it is your choice. We know that 30 days with a product can be convincing. Give me a call 1.800.346.7946 or PM me and I will try to make a Force Fin connection in your area.
No “snappy slogans and funny pictures” included.

By no means are you making a “confrontational comment” – It is a forum- We appreciate your feedback and interest in this thread. I try to hyperlink additional information to my posts and allow members and guest to link to extra info if desired. Don’t hate the internet LOL If you are commenting on the annoying content, thanks again for reading the links and we appreciate your feedback. I am looking forward to the re shoot for the Frog Kicking video. We had no intention to insult the viewer’s intelligence. We just keep hearing that you can not Frog Kick in Force Fins. It will be a great day when the vis is right and we can re shoot that video in the open water with rebreathers, maybe twin set ups, with gear in the divers hand.

You are not “completely missing the value” you are missing the Experience!

Being a Jet Fin user from dive #1, this thread caught my attention.

I've always regarded FFs as a diving equivalent to snake oil, and DA's review at least revealed that they might not be that bad after all.

BUT. If you really want convince the crowd that really care about their propulsion, you're not going to do that with snappy slogans and funny pictures. Just get hold of somebody who really knows their frog, mod frog, helicopter turn and backward kick and shoot some video with them. I've mostly seen Force Fin videos of people with bad trim doing scissors kicks at a pace completely irrelevant to scuba diving. Unless you're into short distance swimming competitions, that is. The only video I've seen showing frog kicks with FFs wasn't really convincing, the diver either wasn't that hot with advanced propulsion techniques to begin with or the fins were to blame. Given DAs evaluation I'd assume the fins weren't entirely at fault there.

This is a bit confrontational, but the material behind those links was just somehow really annoying. Like the whole point of diving was to kick like crazy with no regard to environment or other divers. I'm just completely missing the value proposition of FFs, especially considering the price.



//LN

 

[DA Aquamaster]

I spend a lot more time underwater maneuvering myself precisely, than I do trying to generate tons of force -- the only place I've had to do that was in high-flow caves in Florida. To maneuver precisely in my Jets, I use my ankles and the muscles in my feet. I wonder how well this works with the foot pocket in the Force Fins -- DA, can you comment on that? We've kind of gotten focused on sheer power here, but there's a lot more to finning than that, even in caves.

I did more testing this weekend and played with the foot pocket adjustments a bit, but I got nothing that would approach the feel of the OMS Slipstream or Jet Fin.

The word I kept using on the phone with Marci this afternoon was "snap". Like you, I am using lots of small subtle feet and ankle movements where I get/rely on immediate response for very precise movements and attitude changes. I cannot get that same level of response with the SD1 - things happen, but slower and with a lot less feel.

Admittedly, there is probbaly some bias involved as I am very familiar with the Jet Fin and Slip Stream, but baised or not the Jets and Slipstreams work exceptionally well in a cave environment.

 

[DA Aquamaster]

I set up a 150' measured course today and did some timed speed runs. Times are the average of 3 trials. The range in times for all of the trials was 7 seconds or less so the results were fairly consistent.

The Slipstream numbers first...

Normal "economy cruise" speed with a frog kick.

45.5 kicks, 134 seconds - 67 fpm.

Maximum sustainable speed using a frog kick.

44 kicks, 80 seconds - 112.5 fpm

Max sustainable speed using a flutter kick.

60 kick cycles, 70 seconds - 129 fpm.

The SD1 numbers...

Normal "economy cruise" speed with a frog kick.

70 kicks, 169.5 seconds - 53 fpm.

Maximum sustainable speed using a frog kick.

68 kicks, 120 seconds - 75 fpm

Max sustainable speed using a flutter kick.

70 kick cycles, 80 seconds - 112.5 fpm

The subjective stuff...

1. The SD1s were faster than I would have inititially guessed - they accellerate fairly slowly over a half dozen kicks or so, which tends to mask your impression of their actual speed once you get there.

2. The SD1s were in their prime in the flutter kick. They were slower than the Slipstreams, but still did a respectable 112 fpm and I could have maintained that speed a lot longer than I could have with the Jet Fins in a flutter kick. Over a mile, I suspect the SD1s would be significantly faster than Jet Fins or Slipstreams using a flutter kick.

However, in terms of accelleration and responsiveness, they still lag significantly behind the Slipstreams.

3. The SD1s use a different set of muscles. The large bladed Jets and Slipstreams require strong thigh muscles for peak efficiency while the SD1s seemed to demand a lot more from the lower leg muscles. By the end of the SD1 frog kick trials I was close to cramping and could definitely "feel the burn" in the front of my calves just above the ankles. I suspect with regular use and and improvement in the endurance of those muscles, the times would probably improve.

4. As noted in the previous post, the SD1s back up pretty easily. But I noted that practicing backing up in them served as excellent training for backing up in my Slipstreams. Using the same techniques with the Slipstreams greatly improved my accelleration and speed backing up. I am back kicking better in the Slipstreams than I ever have before in any fin.

My conclusions:

The SD1s would be ideal for distance swimming using a flutter kick and the speed is both very respectable and far more sustainable than with a Jet Fin/Slipstream. I can see why the military likes them and I can see why some people are almost fanatical in liking Force Fins.

I also think that the ability to get maximum performance from them would, like a Jet Fin, require some practice and the development of the specific muscle groups that get used. After all, when I started rog kicking in Jets, it was a while before I could frog kick exclusively and comfortably through an entire 90-120 minute dive.

But they do frog kick significantly slower, although the difference gets lower as you go slower, and the "soft" feel makes them less suitable when making minor trim, attitude changes and small precise positioning movements. And while they back up easily, they lack speed going backward compared to a Jet Fin/Slipstream.

Consequently, while I can see why some users absolutely love them, I don't forsee trading in my Jet Fins and Slipstreams any time soon given that I am primarily a cave diver as Jets seem to be very well suited to that specific role.

 

[meesier42]

nothing too surprising here to me, at half the size and twice the flexibility the SD-1 is somewhat expected to lag in the specific testing that you did. I am mildly surprised by the flutter kick, but as you noted, practice with the fin and the muscles used for a strong flutter when using a flexible fin is completely different then it is with a stiff fin. Primarily in the knee bend with the more flexible uses much less knee bend.

thanks for the information and the review.

 

[BabyDuck]

but flutter isn't with *any* knee bend...or are you thinking mod flutter? that's not what he did, he used straight-up flutter.

 

[meesier42]

if he did a dead straight knee flutter kick with slipstream he would be super human. the power of a flutter kick comes from twisting the hips which loads the thighs, flexing at the knee to snap the foot through the finish. If he had no bend in his knee either he is superman or he is going really slow
to be honest, although the frog kick speeds are quite good, as I look through my 10 years of fin testing, 110-130 fpm is really not that fast for flutter kick, as evidenced by the fact that he can frog kick nearly as fast as his flutter. most of my testing has people sustaining 180 fpm or more in 100-200 foot sprints and some of the best swimmer in the best fins can cover a mile in about 20 minutes. But I am guessing that DA probably had his tech rig on slowing him down quite a bit, with that much gear on, the drag at speed is killer, as we all must remember that underwater drag is proportional to the square of speed.

 

[DA Aquamaster]

I agree, with a big fin, there is no such thing as a straight out flutter kick, and "modified flutter" is more accurate description, but the degree of knee bend is a lot less than what I would consider a "modified flutter". As a cave diver, I view a modified flutter as something with lots of bend to ensure that nearly all the water goes aft rather than down for silt control.

Even when attempting a straight flutter kick with a large stiff blade, there is still some bend in the knee as you need to get the blade to bend enough to recoil at the end of the stroke and you can't do that straight legged with a stiff fin.

---

And yes, drag increases as the square of the speed. I did the test in a dry suit, doubles, can light, etc for exactly that reason to reflect a realistic cave configuration. In a single tank and travel wing, I can fly in a set of Jet Fins, and I suspect the Force Fins would do very well there as well. I just don't dive that configuration often so it was not the basis for my testing.

Plus, I almost never flutter kick. When I initally started frog kicking in Jet Fins way back when, it took a long time to develop the strenght and stamina to be able to do it the whole dive with speed and with no discomfort. I suspect my flutter kicking skills and speed have not benefitted from the near total lack of flutter kicking.

And, for a cave diver, 180-200 fpm is what you get using a scooter. A mile in 20 minutes is 264 fpm and that is well beyond what even the best scooter can do towing a dry suited diver in doubles.