Split fins

[The Chairman]

The BIGGEST difference I see is how you kick with them. The Jets get speed/power from kicking harder. The Black Twin Jets get speed/power from kicking faster NOT harder. I believe that the best analogy would be the pitch on a blade. The Jets have BIG pitch, which make them harder to kick, but an awesome acceleration when you do. The Twin Jets have a variable pitch, that almost works in reverse of how you like it at first. The faster you go (or the harder the push), the lighter the pitch. BUT, as I grow use to them each and every dive, I find myself using this to my advantage. The fins are far more aerobic in nature than the Jets, and unless you treat them as such you are only fighting yourself. Kick them hard and they are useless... increase the frequency and reduce the intensity of your kick and you will zip right along. You can't start out as you normally would either. Quick, tiny little kicks first then increase the intensity to normal.

As for the various kicks, I can not answer that, as I am still ignorant of the ways of the caver. I know that I do back up and helicoptor in my own way. I have really been concentrating on holding my hands and NOT using them for attitude or directional adjustments. Its like re-learning to dive for me, but the Twin Jets are doing it perfectly... and did I mention my new adjustable spring straps??? 1.5 inches longer (13.5" total) to accomodate the repositioned attachment points. I could lossen them by another 1/2" or tighten them another 1.5" from where I have them now. I still have a couple of wrinkles with the system to work out, but I love the way they are coming along.

 

[The Chairman]

I have heard it said that it is better to go to the well many times than to try and tote it all at once. This is the principal of the Twin Jet. You may move less water with each kick, but I truly believe that you move more water per Calorie spent. Try and ride your ten speed in tenth gear all of the time... that's the Jet Fin. Now introduce some automatic shifting... so you are inputting the same power, whether the finning is harder or softer. No more need for massive leg muscles to propel you through the suds... just a leaner, more aerobic kick to move at top speeds, or very little if you just want to crawl.

So you have to learn how to kick it differently if you are going to enjoy all of the benefits. AND, it will take some time to adjust your style and for your body to adjust to the difference. I am glad I did!

So, why don't I sell my Jets??? Other than them being the oldest piece of gear I own ( I bought them in '69 or '70) they do have their place. WHENEVER, I know that I have to do a tired diver tow for time, I put them on. Maybe later, as I perfect my technique with the black Twin Jets, I won't want to. But right now, I find that trying to hump a guy through water while being timed; I want the stiffest, baddest piece of rubber in the pond on my feet. They are indestructible, and they will ALWAYS be a classic. I may hate them at times, but I will always love them for where they have taken me.

 

[DivingDoc]

Originally posted by NetDoc
The fins are far more aerobic in nature than the Jets, and unless you treat them as such you are only fighting yourself.

If by "aerobic," you mean that you are using more oxygen, this has not been shown to be the case. Rodales found that the split fins were more efficient than paddle fins, resulting in lower air consumption.

See:


http://www.scubadiving.com/gear/propfins/

And as for splitfins working by "pushing water down," that is not correct. Look at the pictures in the Rodales article listed here:

http://www.scubadiving.com/gear/smackdown/

Seems to me, the paddle fin pushes water down more and therefore would have to cause more silt-up.

Just MHO.

 

[The Chairman]

I did not mean to imply that it consumed more oxygen. Just as anaerobic (sp?) excercising ulitmately uses more oxygen than aerobic, Jet Fins use more than Twin Jets. The Jets are like lifting 250 lbs all at once... the Twin jets are like lifting 50 lbs five times. One completely exhausts you, the other lets you lift some more. Both accomplish the same amount of "work". Is this as clear as mud yet???

 

[Drew Sailbum]

Originally posted by NetDoc
I did not mean to imply that it consumed more oxygen. Just as anaerobic (sp?) excercising ulitmately uses more oxygen than aerobic, Jet Fins use more than Twin Jets. The Jets are like lifting 250 lbs all at once... the Twin jets are like lifting 50 lbs five times. One completely exhausts you, the other lets you lift some more. Both accomplish the same amount of "work". Is this as clear as mud yet???

Trying to fight urge.... cannot resist....

I know what you mean Pete, but you are having the same trouble I do when I try to explain this one. I liken it to the thrust required to send a rocket into orbit. Either a lot of thrust applied few times (blades), or a little thrust applied many more times (splits) - either way you end up in the same place.


But, Anaerobic = without oxygen; you don't use more oxygen during an anerobic process, but you do consume more metabolic fuel to produce the same amount of ATP (basic energy unit your body uses) compared to an aerobic process. Byproduct of anaerobic exercise is the production of lactic acid, which can alter blood pH and increase breathing rate. Your body then shifts to aerobic processes to deal with that lactic acid, and your breathing rate then slows.

 

[MikeFerrara]

Are you guys saying that split fins are like being stuck in high gear? You have plenty of speed once you get going, but not much off the line. Or, is it more like being stuck in low gear? They don't work for the way I dive. I do not kick continuously. I flip or kick and coast, skull backwords or turn on a dime. For me manuverability with minimum motion is the key. When I do kick hard I mean to MOVE NOW not after a bunck more kicks. I do understand why they apeal to divers with leg problems or those that haven't yet developed their finning technique.

 

[Uncle Pug]

Originally posted by MikeFerrara
Are you guys saying that split fins are like being stuck in high gear? You have plenty of speed once you get going, but not much off the line. Or, is it more like being stuck in low gear? They don't work for the way I dive.

The two different brands I've tried were both like being in stuck in neutral for starting out and then stuck in low gear for maintaining cruising speed..... and they didn't take corners too well either.... kind of the best at being the worst.

BTW Mike I agree with you completely on the use of fins... that is the same way I dive... I am not continuously finning trying to get somewhere... or maintain buoyancy and trim

 

[Shadow]

Dive Rite's website has an interesting story about their comparison trials of split fins in a some rather strenuous cave diving current situation that they tried. It's worth a read. It might be biased towards their own fin, but it seemed like a fair test.

My Tusa Zooms get a lot of attention, and I don't seem to have any trouble keeping up with other much bigger people on dives. As far as mucking up the bottom, it's kind of like the saying about guns don't kill people... Fins don't make a mess, it's the divers wearing them that do!

 

[Uncle Pug]

...that I didn't get split fins for my birthday.

I probably wouldn't be here to post on ScubaBoard today....

 

[Shadow]

Like I said UP, it's not the fins, it's the diver operating them...:tease: