Split fins?

[Scott L]

To the OP ...

See??? They just couldn't leave it alone!

Just because an OP has gained the information they sought does not mean more information cannot be shared by others hence the inability to close threads without moderator approval.

 

[vladimir]

My understanding is that since they induce less resistance, they're easier to kick, but since they don't move as much water, they don't create as much thrust per kick. If you are a swimmer, think of doing a crawl stroke with your hand in the vulcan "live long and prosper" position as opposed to with your fingers together.

Different people have different physiology, so while paddle fins work well for me, splits may work better for you.

I was taught to spread my fingers when swimming. A quick search turned up an article from the Journal of Biomechanics that concludes that fingers spread at a 12° angle create the optimal drag. (I realize that's not the "live long and prosper" or split-fin position, I'm just musing.) Extrapolating from the article, perhaps a fin that spread it's surface out and allowed water to flow through it (like the vents on jet fins et al?) might deliver "muscle, hydraulic and propulsive efficiencies." The rationale:

large vortices develop at the closest finger spacing, resulting in a strong back flow increasing the pressure on the dorsal surface of the hand, thus decreasing the pressure differential on the hand and the overall pressure drag. At the optimal spacing, water jets produced between the fingers prevent the formation of the vortex and contribute, via a reduced backflow toward the dorsal side of the hand, to create a stagnation region with the consequent increase in the drag force.

Here's the abstract:

Competitive swimmers spread fingers during the propulsive stroke. Due to the inherent inefficiency of human swimming, the question is: does this strategy enhance performance or is it just a more comfortable hand posture? Here we show, through computational fluid dynamics (CFD) of a 3D model of the hand, that an optimal finger spacing (121, roughly corresponding to the resting hand posture) increases the drag coefficient (+8.8%), which is ‘functionally equivalent’ to a greater hand palm area, thus a lower stroke frequency can produce the same thrust, with benefits to muscle, hydraulic and propulsive efficiencies. CFD, through flow visualization, provides an explanation for the increased drag associated with the optimum finger spacing.

 

[RJP]

I was taught to spread my fingers when swimming. A quick search turned up an article from the Journal of Biomechanics that concludes that fingers spread at a 12° angle create the optimal drag. (I realize that's not the "live long and prosper" or split-fin position, I'm just musing.) Extrapolating from the article, perhaps a fin that spread it's surface out and allowed water to flow through it (like the vents on jet fins et al?) might deliver "muscle, hydraulic and propulsive efficiencies." The rationale:

Here's the abstract:

"Dude, right after you and your split-fins zipped off we saw a leprechaun and a unicorn riding a whale shark!"

 

[highdesert]

Just because an OP has gained the information they sought does not mean more information cannot be shared by others hence the inability to close threads without moderator approval.

How many umpteen split vs. paddle threads ago was it when there was any new information shared? It's now in the predictable pi$$ing contest phase.

 

[Jim Lapenta]

I dive paddle fins exclusively now. Almost. But for a time I had a pair of Oceanic V-12's from a shop just to try them out and see the real differences for me were. They were great in the pool on long swims. No fatigue, no aching knees and ankles, and pretty good speed. I could not for the life of me get any knid of accpetable or even consistent back kick out of them. ALso noticed that they were not as efficient witha frog kick or modified frog. Which by the way also releived my knee and ankle pain with paddle fins. A few weeks ago I did an hour and 17 minute dive with no pain, no fatigue, decreased air consumption, and greater area covered. Aqualung Blades fins, Dbl LP85's. and dry suit. Oh and my Torpedo 2000 scooter. Fins are fins but fins and a scooter are the shizzle!

 

[Scott L]

My congratulations to merxlin for telling the OP everything he really needs to know about this subject ... seriously!

How many umpteen split vs. paddle threads ago was it when there was any new information shared? It's now in the predictable pi$$ing contest phase.

Not many at all...like this one according to your glowing review of merxlin's comments which you also thanked.

 

[Scott L]

Oh and my Torpedo 2000 scooter. Fins are fins but fins and a scooter are the shizzle!

Jim, are you bringing that scooter to ITK's?

 

[Jim Lapenta]

Nah, not going to make it. My son is coming home from Afghanistan on June 15 and scheduled to be in my area mid July. I have not seen him in two years. There are few things more important than diving to me but he is definitely one of them. The keys will be there next year. I only have 6 vacation days left since I had to use up some when my wife passed away. Priorities are much different these days.

 

[scubafanatic]

After the dive, do you get them to tell you about all the stuff you missed as you zipped along the reef?

:cool2:

nah, I usually just bore them after the dive with all my Whale shark close encounters they missed out on 'cause THEY couldn't keep up with the Whale sharks like I could!

 

[highdesert]

Not many at all...like this one according to your glowing review of merxlin's comments which you also thanked.

... and that was how many posts into the thread? Oh yeah ... 4