Atomic Split Fins vs. Scubapro Jet Fins

[djanni]

Sorry but I have to disagree.

I've been behind many divers who don't realize they're leaving a large silt trail as they speed off 2 feet off the bottom flutter kicking.

A silt trail from "speeding off 2 feet from the bottom flutter kicking" is hardly limited to split fins. However, it does illustrate the temendous force one can generate with the vortex created by a split fin.

I have never owned splits...

That pretty much says it all right there.

I pretty much don't trust anything in magazines like that. I've seen some dangerous things in magazines such as that--an example being tips for making your gas last longer. They were practically advocating skip breathing!

Sometimes being a skeptic is a good thing.

 

[wunat]

At NCSU where I took scuba they performed a test between SP Jets and Twin-Jets. Same diver--took twice as many kick cycles to get across a 25-yard pool with the Twin-Jets than with the standard Jetfins.

Just my share of experience on the performance difference on the Twin Jets vs. Twin Jets. I am in the final part of my DM training and is getting ready for my stamina test. One of the test is 800m mask+snorkel+fin surface swim. In my first attempt, I go with my Jets. Then with pair of Twin Jets I borrowed from my instructor days after my first attempt.

The Jets made the 800m in a shorter time than the Twin Jets by about a minute. But I have to say that Twin Jets are certainly less power demanding than the Jets in completing the laps.

 

[bradshsi]

It's "easier" to use because there's essentially a hole down the middle of the fin that gives, every time you kick.

That's a gross oversimplification of the rather clever fluid dynamic principal used in split fins. They also require less effort because they are generally more efficient.

I've been behind many divers who don't realize they're leaving a large silt trail as they speed off 2 feet off the bottom flutter kicking.

That's a dubious correlation. You link a type of fin with silting without much supporting evidence. You might as well observe that all divers who kick up silt trails were wearing tanks on their backs Spits do frog kicks just fine IMO. Further, the amount of silt kicked up has much more to do with diver trim and kick type than the type of fin.

Also remember that they're essentially useless for proper backwards kicking and helicopter turns...

Not correct. Splits can do all these kicks. Not as precisely as a paddle fin, but they can be done. Check out http://www.ndsu.nodak.edu/instruct/grier/fins.html for this and other discussions on these myths regarding backward finning.

I pretty much don't trust anything in magazines like that. I've seen some dangerous things in magazines such as that--an example being tips for making your gas last longer. They were practically advocating skip breathing!

Fine, but the link posted is an independent review and is not magazine hype.

 

[Jay Roy]

Everytime I see a fin ad in a scuba magazine, I find myself wondering, who cares how fast you can go? The general idea of this sport is to look at things and most people I see kicking like stink are the ones on the boat saying, "no, I didnt see that, or that"

 

[Al Mialkovsky]

I did something similar when I went to work for a shop, tested everything they had in the shop. I didn't do it exactly the same as you but since my legs are old those jet fins just didn't work for me.

I also factored in distance per kick.

Overall winner for me after testing 12 different fins were the ScubaPro twin jets.

Go figure, we're all different.

 

[SparticleBrane]

It might be a gross oversimplification, but you'll note that when you kick with them, they give in the middle, whereas Jets don't.

I'm linking the silt trails to split fins specifically because the split fins are useless for good proficient (ie: correct) frog kicking. Sure other divers silt up the bottom but if taught correctly they could probably frog kick in their non-split fins.


For me I want something that's going to give me maximum thrust when I need it, and that happens to be Jets. I also want something that's going to allow me to do helicopter turns and backwards kicks properly, which splits are terrible at. With splits, while you can kick backwards, it isn't as efficient and you have to wait for the floppy parts of the blades to settle back into position.

And to be honest, I think splits are just another gimmick (see: SpareAir) and plain look silly.

 

[*Floater*]

In OW class I was only taught the flutter kick. I tried both split fins and paddle fins, and the splits felt much better (for flutter). I then bought a pair of Tusa x-pert zooms and they rocked; fast, effortless, just as advertised. Then I learned about other kick styles and realized my splits sort of sucked for how I wanted to dive. I sold them soon thereafter.

 

[scubadobadoo]

The problem with most test is the only thing the testers seem to be interested in is which is the "fastest", many of us could care less how "fast" a fin is. I try to go slow. Control and precision are what is important to me. Efficency depends on what you want the fin to do. The fastest fin may well not be the best at turning or reverse. I carry a camera a lot of the time, every fish in the water can swim faster than me so I need to ease up on them and then slowly turn or back away to keep from spooking them. A fast fin with little control is useless to me. On the other hand, for some divers I see zooming around the water a fast fin may well be what they want. There is a reason the old Jets are still popular and it's not because they are pretty or cool.

I agree 100% but I will concede that my agreement doesn't make me "right." It just means that I personally agree.

 

[Timotheus]

I'd have to agree with those ANOVA results. I think what I was going after was the idea that split fins are faster. The magazine adds and "tests" make you think that if you fork over lots of money for splits, you'll blow everyone else away. For me, I like the control the Jet Fins provide.

 

[djanni]

Even if there is not a "real" effect of thrust of a kick on speed (the null hypothesis), the test result groups are likely to have different average speeds. The likely range of variation of the averages if our thrust-effect hypothesis is wrong, and the null hypothesis is correct, is given by the standard deviation of the estimated means:

/N½ where

is the standard deviation of the force of all the thrusts and N (10 in this example) is the number of thrusts in a group. Thus if we treat the collection of the 7 group means as data and find the standard deviation of those means and it is "significantly" larger than the above, we have evidence that the null hypothesis is not correct and instead thrust has an effect. This is to say that if some (or several) group's average thrust is "unusually" large or small, it is unlikely to be just "chance".

So it's therefore obvious that Timotheus kicked much harder with the Twin Jets yet the additional speed achieved was negligible.

I'd have to agree with those ANOVA results. I think what I was going after was the idea that split fins are faster. The magazine adds and "tests" make you think that if you fork over lots of money for splits, you'll blow everyone else away. For me, I like the control the Jet Fins provide.