The Debate : Split Fins or not ?

[meesier42]

there have been lots of "test" with them (see Rodales Scuba Diving, Undercurrent, and etc), but only 1 true study that I know of that included splits (performed at the University of Buffalo),

All of them basically say the same thing, some people perform better with splits, others perform better in paddles, and the physiological differences in terms of O2 burned is more dependant on what you are comfortable in then the fin itself. Of course, there are a few highlights here and there that stand out from the crowd, but that is not the point. In the Un. of Buffalo study concluded itself with a statement, to paraphrase it, it stated that the fins the divers felt were most efficient were infact the least and vica versa, this test however only examined efficiency moving in a straight line at constant speed, and did not look at manueverability, sculling, backing, etc...
I will say, I can do all of these with every fin I have used, but it can really be a PITA with some designs.

 

[jmitch3938]

Does Louisiana have a college football team ? lol..yea, Notre Dame ! : )

 

[jmitch3938]

Totally agree, when I'm doing any deep dives or confined spaces dives, I'm sticking to my full fins, less stir up and I can feel the difference between the two types of fins...

 

[Teamcasa]

If you like splits, use 'em. If you like Jets, use 'em. Me, I'll stick with my Omega Flip fins for shore diving, Cressi Reactions for travel or boat diving. My wife loves her Atomic Splits.

I don't race anyone when I'm diving and if the current gets too heavy, I surface.

 

[pescador775]

From the U. Buffalo study reported by Undercurrent in 2004:

The researchers concluded: “Based on the physics of fin swimming ... it is clear that some fins have better performance (Mares Attack, Apollo Biofin) than other fins; however, this cannot be ascribed to a single fin characteristic. The research also made it clear that Venturis, vents, troughs, and splits did not improve the performance of the tested fins.” As a result, they determined, “Further work is needed to develop the optimization of fin characteristics, by lowering drag (kick depth-rigidity) and maximizing efficiency (kick frequency-flexibility), to minimize energy requirement and maximize performance.”

Scubapro Twin Jets, manufactured from the same Nature’s Wing patent as the Apollo, were stiffer but did not perform as economically as either the split or taped Apollos. In fact, the Scubapro fins (9%) had a significantly lower maximal aerobic velocity than all the others.

Scublab reported the similar results for the Scubapro.


Reading the entire study might be of interest to some but interpreting the results could be tricky, and don't expect any "Perry Mason" AHAH. In the end, they acceded to the obvious and repeated the same conclusion reported by every major tester such as Scubalab. Well, you read it and, of course, further research is needed. Now, that has a familiar ring.

Dr Grier's studies were comparable but, personally, I think they were more informative for the consumer.

 

[meesier42]

personnally my favorite quote from the U of Buffalo study is
"the hamstrings of men are weakers than the quadriceps, thus the power stroke should generate more thrust than the recovery stroke,..., however this type of fin was not available for testing"

and then
"fins where the successive TE segments that progressed to 90 (degrees) to the horizontal produced the most thrust during the power phase, which was predicted by the Lighthill Model, As most of the power was generated in the power phase, and little in the recovery, it may be advantageous to have higher thrust in the power phase but relieve the force required for the recovery"

sounds to me like they have just decribed a fin that I know of, but again that not the point and I don't want to start a new argument. I am not sure where the quote about the Twin Jets came from but they were not included in this study, so I am not sure what the basis for it is.

BTW- the study can be found here for everyone to read Rubicon Library.

 

[pescador775]

There was one competitor to the Apollo Biofin, the Attack. If I recall correctly, the Mares Attack was a slipper fin with very stiff foot pocket and blade. Overall length was 60 cm and construction was of graphite composite and other plastics. I seem to remember that the Germans tested it and found that it had huge thrust. Also, the foot pocket would bite into the flesh and produce cramps in the arch. It cost about $600, similar to another hi performance fin, the ex-something.

 

[jeffchandler1]

After a serious leg and knee injury three years ago, I had to go with something that would put less strain on my knee. The split fin design was just the ticket, and I was glad to make the switch.

My faith in "split" was rattled a year ago in Jamaica, seeing what this big, strong dive master could do with a couple big paddles. I saw him haul a distressed diver back to the boat in heavy current. The novice diver had run out of air, and was breathing off the dive masters tank. The leader came back, finished the dive, and had air to spare. Certainly, he was a good diver. But he was still able to get a lot of propulsion from those big flippers.

I have concluded that the debate comes down to strength. I bike ride in Colorado up some big hills. I'm much more efficient with smaller gears spinning at higher speeds. I my twenties, the story would be different. I would get a monster 54 tooth front gear and power up the mountain with no worry about blowing out my knees. The years have taken their toll, however.

The same analogy seems to hold for fins. If you are an average Caribbean diver who goes out 2-3 times a year, buy the split fins. They won't wear you out. If you are a strong kicker, you will do well with paddles. But then, if your are that strong, you already know that.

NOTE: If you are a new diver, you are not a strong diver. Buy the split fins.

What I don't like is the big strong swimmers looking down upon us middle-aged vacationers, sneering at our split fins as if we were polluting the waters. We like our split fins. They do what we want them to do. We aren't pretending to be Mark Spitz. And, we find great solace in our fast-cadence flutter kick.

Just one more analogy. In Colorado, all the tourists come in to ski with their big, wide "shape" skis. I refuse to buy the shape skis, as I like my long stiff Volant skis. I'm an experienced skier, and I like the acceleration and quickness of the straight skis. Nonetheless, there are certainly some advantages to the short "bubble" skis. But you'll never see an olympic downhill racer on those fat little things--get the big sticks.

Don't be ashamed or intimidated for using equipment that is suited for you. Find a fin that fits, is easy to get on/off, and that matches your diving style.

 

[lmorin]

.............
NOTE: If you are a new diver, you are not a strong diver. Buy the split fins.
.............
Just one more analogy. In Colorado, all the tourists come in to ski with their big, wide "shape" skis. I refuse to buy the shape skis, as I like my long stiff Volant skis. I'm an experienced skier, and I like the acceleration and quickness of the straight skis. Nonetheless, there are certainly some advantages to the short "bubble" skis. But you'll never see an olympic downhill racer on those fat little things--get the big sticks.

Don't be ashamed or intimidated for using equipment that is suited for you. Find a fin that fits, is easy to get on/off, and that matches your diving style.

Nonsense. There is absolutely no support for the view that if you are not a strong diver you should use split fins. Ridiculous. And, my view has nothing to do with the issue of splits vs paddles. My wife is a good example. She is a very efficient, but not strong, swimmer who uses Mares Volo full foot fins that are extremely light and flexible. They actually bend at right angles, even with gentle kicks, because they have hinges that intend that action. She has zero difficulty keeping up with me and I have bigger, much stiffer fins (no longer manufactured Mares open heel fin).

The published information about fins supports the view that nobody really knows what constitutes a great fin. And, even when certain features suggest they yield better results, divers choose to ignore them. An example are the results from Scuba Diving Magazine that suggest full-foot fins are better than open heels. But most divers seem to shun full-foots, even if they are diving off a boat.

As for skiing and skis, all those "tourists" who come to Colorado with "their big, wide "shape" skis" ...., most probably come from places, particularly the northeast, where snow surfaces are very hard or granular. Shaped skis are perfect for such conditions. Most folks don't have more than one pair of skis. If I lived in Colorado or Utah, I wouldn't use shaped skis either. As for Olympic downhill racers, they use skis that are long and not shaped because those skis, like ski jumping skis, don't need to turn quickly. Slalom racers do use short, shaped skis precisely because they facilitate turning without speed loss on hard surfaces.

 

[richerso]

Oh boy! Split fins or blades? I might have to go ressurrect that old RJP post from a few months back where he talks about diving on the U-869 using air, silting up the place, losing his SpareAir, puncturing his BCD, using the 'up elevator' lever on his i2 BCD, etc. etc. etc. Now that was funny!

Seriously, I have been threatening to conduct a massive comparative field study between splits and blades by utilizing the massive volunteer pool available here at SB. But alas! I haven't done it. I do have a draft copy of my field study methodology. I feel like it needs more work though. And I see some familiar names in this thread from previous discussions.