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Scuba Forum / General / December 2007Science project on Fins - RESULTS
A month or so ago I asked you all for some ideas on Science Projects for my 11-yr.old son to do. We finally settled on testing different fin styles to see how they compared. We tested three fins over a 100-ft course, swimming each fin three times. He measured the time and number of kicks. The fins we tested were a Scubapro Split fin, a Mares Quattro, a full foot snorkle fin (Mares Plana Avanti) and a freediving fin (I forget the brand). The quattro and the split fin were nearly identicle with the Quattro having a statistically insignificant advantage (each took ~40 kicks in 25 seconds). The free diving fin was the winner - it covered the distance in about 20 seconds with with 25 kicks. The snorkle fin was just a kick and a second behind. As I was the test subject, I ca give the following anecdotical statements. The split fins were the easiest to kick, but almost too easy, kinda like a bike in one gear to low. The long fins were the hardest but in a real world situation I would have been going a bit easier. I tried to keep my kick speed consistent. For a last measure, I did the distance bare footed (no hands, just feet). That took 56 seconds and 120 kicks (I didn't try to keep that consistent, I was just kicking to get it done. So what did we decide? The long fins ($120) were the best but the snorkel fins are the best buy - they only cost $40. Again, thanks for everyone's help. > a full foot snorkle fin (Mares Plana Avanti) and a freediving fin (I > forget the brand). Plana Avantis are not snorkel fins. They're diving and snorkeling fins. In fact, they're one of the most popular full foot diving fins on the market. It's a shame you didn't test the Quatro Power fins, which are even more powerful than the foot pocket/strap Quatros. Unfortunately, the Quatro Power fins do not work well on the surface, at least they don't for me. Split fins are not faster, they are marketing hype. They accomplish nothing different than reducing stiffness, reducing blade surface area or both. All they do is inefficiently spill thrust. > Split fins are not faster, they are marketing hype. > > They accomplish nothing different than reducing stiffness, reducing > blade surface area or both. > > All they do is inefficiently spill thrust. Cite? In article <3df3eea8-48d9-4699-af63- 3f941856a46a@d61g2000hsa.googlegroups.com>, mossman@qnet.com says... > > Split fins are not faster, they are marketing hype. > > [quoted text clipped - 4 lines] > > Cite? One of the things that came from the Healy incident was that NOAA now prohibits split fins for any diving that involves current, heavy loads or a drysuit. http://www.ndc.noaa.gov/newsltr/ts_07march.pdf http://www.hawaii.edu/ehso/diving/NOAA%20Public%20Statement.pdf This is not the kind of test you're probably looking for. I've tried all kinds of split fins and don't need any science to tell me they're not suitable for what I do. I still laugh when I think about the guys at the Navy EOD unit in Charleston. They were given Twin Jets, and they "fixed" them with plastic and duct tape. >One of the things that came from the Healy incident was that NOAA now >prohibits split fins for any diving that involves current, heavy loads [quoted text clipped - 3 lines] > >http://www.hawaii.edu/ehso/diving/NOAA%20Public%20Statement.pdf Though there's a certain lack of unanimity in test results. Probably because not all split fins are identical (and not all non-split ones are, either). Scuba Diving's tests showed some split fins doing better than the best non-split, even in the basic tests like speed. See http://www.scubadiving.com/gear/fins/200510_scubalab_fintest and http://www.scubadiving.com/gear/fins/200411_scubalab_finfight  SignatureRon (user ron in domain spamblocked.com) > Though there's a certain lack of unanimity in test results. > Probably because not all split fins are identical (and not > all non-split ones are, either). > Scuba Diving's tests showed some split fins doing better > than the best non-split, even in the basic tests like speed. A manufacturer's rep often came to the pool we used in SC with different fins he wanted us to do timed tests with. He could always find someone who would be faster with splits or whatever other new designs he brought, but I am consistently faster with jet fins or Mares Quattros. The split and robocop fins just don't work well for me, and I can't really see them working at all if you are pushing doubles and stages into somewhere like Devils Eye or Manatee. > > Though there's a certain lack of unanimity in test results. > > Probably because not all split fins are identical (and not [quoted text clipped - 9 lines] > really see them working at all if you are pushing doubles and stages > into somewhere like Devils Eye or Manatee. Hmmm... > As I was the test subject, I ca give the following anecdotical > statements. The split fins were the easiest to kick, but almost too > easy, kinda like a bike in one gear to low. The long fins were the > hardest but in a real world situation I would have been going a bit > easier. I tried to keep my kick speed consistent. I'm not a split-fin user, mainly because I don't feel any reason to switch from fins I've already paid for until they're completely worn out (going on nine years and they keep on kicking), but you stated the number of kicks was the same as with the Quattros. Wouldn't the ease of kicking the split fins allow for faster kicking, therefore getting in more kicks and more propulsion in the same amount of time as the Quattros? I believe that's the idea of split fins, to use a faster "bicycle" kick instead of the full-leg scissor kick that most of us are trained to do on standard fins. With the same amount of total effort expended, the split fin kicker should be able to go farther in the same amount of time. Of course the big reason why many of us don't switch to split fins even if they are proven to go faster or farther is because we don't want to necessarily go faster or farther. It took me hundreds of dives to learn how to slow down enough to get more out of my dives than people who cover twice the distance in the same amount of time. Were it not for the need to occasionally sprint underwater or kick against current, I'd dive barefoot for sure (my size 13-EEEs are almost as big as Jet Fins anyhow). Also, I like to dive with my nose about an inch from the stuff I'm looking at. Split fins kick up too much stuff with the whirlwind-like vortex they leave in their wake. (snip)> about an inch from the stuff I'm looking at. Split fins kick up too > much stuff with the whirlwind-like vortex they leave in their wake. Thank heavens, you finally mentioned that part. I've never seen a diver yet that was using split fins, that didn't kick up a world of crap behind them. If a diver out there is having cramping problems or has some other reason they need to dive a fin that will make things easier on them, then they should check out the Mares Volos. Just about everything that can be done with a stiff fin (frog kick, helicoptor, etc) can be done with the Volos. "chilly" <slarson@shaw.canada> pounded away at his keyboard resulting in: :Thank heavens, you finally mentioned that part. I've never seen a diver yet :that was using split fins, that didn't kick up a world of crap behind them. I see lot's of divers wearing lots of fins and I think the type of fin, split vs conventional, has no effect whatsoever on how much sand gets kicked up. Dan Bracuk Never use a big word when a diminutive one will do. > "chilly" <slar...@shaw.canada> pounded away at his keyboard resulting > in: [quoted text clipped - 5 lines] > fin, split vs conventional, has no effect whatsoever on how much sand > gets kicked up. True. Most divers don't know how to fin over sand without kicking up the sand no matter what fins they're wearing. But split fins are designed for bicycle kicking, not frog kicking. Divers with standard fins will still kick up sand if they bicycle or scissors kick, but there's no comparison between a diver frog-kicking with bent knees versus a split-finner who can't efficiently frog kick. |
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