The differences between split fins and paddle fins

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This instructional video by Scuba.com describes the two major types of fins available. There is the paddle fin and the split fin. The paddle fin uses more effort from your leg to push the water. It's similar to a boat paddle, whereas the split fin is similar to how a propeller from a boat works. The water goes through the blade and creates vortices that push you along. Ultimately the split fin reduces the amount of energy you use, and it saves your air because you're using less energy.

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• fins
• paddle
• split
• instructional
• scuba
• diving
• fin

[flspy]

I bought a pair of split fins based on all the rave reviews. I liked the idea of less strain on knees and ankles. However, I am apparently a much stronger swimmer than I thought because compared to my old Cressi Specefrogs, my Tusa split fins were like trying to kick with wet blankets on my feet. They are whippy and gave almost no propulsion in current. Am I supposed to adjust my whole kick just to wear these fins? I also didn't notice any big difference in small speed maneuvers.

[scubacom]

@flspy They are supposed to be soft and very "floppy" feeling. The beauty of them is in allowing for any kick strock but over all they work best with a bent-knee flutter kick similar to that of a normal swimmer. You'll find they are easier to kick and since you are working less hard you don't consume as much air.

I have used them in as much as a 3 knot current successfully, and have on more than one occasion proven their superiority to other fins in races in a pool against

[scubacom]

everything from Force Fins, to the paddle fin of your choice and even long bladed free diving fins.

[TCSkiFilms]

Split fin, paddle fin, mini fins, small fins, big fins..... whatever. The smaller the surface area the less water displaced. Pick fins based on your leg strength and the requirements of your dive environment (high currents and lots of gear to move will likely be better wth larger paddle fins but also requires stronger legs to use them). Split fins will give you a slower cruise speed and slower acceleration but if you aren't trying to go fast or cover large distances....then go easy.

[scubacom]

@TCSkiFilms Again more misinformation generated frequently by "old timers" and/or shops who don't understand the fins or the engineering. Split fins work great with a load. That's why the Imax filmers use them with their large multi-camera framed structure underwater. And, not that speed underwater is generally something most divers need to worry about, but I have personally raced a person using long bladed free dive fins in a pool and won with very little effort involved.

[k956upg]

basic....split feels more natural & is great for cruising but the vortex effect is blown away by current so in the sea there no good unless slack...this is very obvious & i even gave my split fins away as i dont go into still lakes much..

i have seen the difference & felt it bigtime..also its stupid not to realise a current would displace the vortex & thus your kicking effort.

force fins or slingshot fins are noticably better.

most fins feel alike..split fins are only good in still water.

[scubacom]

@k956upg I can't disagree more. I personally have held in a current under the Tacoma Narrow bridge when a dive operator there misjudged the tide change and have used them in the current in Agate Pass in Puget Sound. Not to mention in the surgy S. California waters off shore here. I have never noticed any disadvantage when using my split fins in a current.

[TCSkiFilms]

@TCSkiFilms Misleading, biased or an 'old timer' etc...NOT! Probably 90% of the typical diving (start, stop, turn,  short distances etc.) would be better off with Split Fins, much better. I am equally sure that split fins will eventually come in different sizes (not shoe size but length/width/stiffness etc). Different models for different diving conditions. Top speed, distance, fastest lap, strongest pushing force and most manuverable... Same fins for every event..NOT!

[TCSkiFilms]

@TCSkiFilms Misleading, biased or an 'old timer' etc...NOT! Probably 90% of the typical diving (start, stop, turn, short distances etc.) would be better off with Split Fins, much better. I am equally sure that split fins will eventually come in different sizes (not shoe size but length/width/stiffness etc). Different models for different diving conditions.Top speed, distance, fastest lap, strongest pushing force and most manuverable... Same fins for every event..NOT!

[TCSkiFilms]

Unless split fins can defy physics I am still correct. Split fins is like a lower gear ratio. You will kick easier and faster than a larger fin. Bigger split fins will yield more water displaced and smaller split fins will move less water. The smaller the easier to kick. Are the smaller ones better? Split fins are easier because they displace less water 'per stroke' .Your fastest kick speed with splits will not be as fast if you kick "AS FAST" with bigger fins split or not.

[TCSkiFilms]

This is for the physics guys and fluid dynamics geeks:

Fins are like sails on a boat or wings on a plane. Boats are pulled thru the water and not pushed and wings lift up not push up. It is the vacuum created on the backside that moves you. Same in fins.

"In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy."