No more pain and suffering
One of the most common complaints that people have about diving is that their feet and legs hurt when they try to kick with today's long or stiff fins. Their arches or calves cramp, their toes are smashed into the end of the foot pocket, their legs tire... Sound familiar?

The primary cause of all this pain is that most fins are designed to concentrate much of the force from kicking on the smaller muscles of the lower leg and feet. And those muscles simply can't take the stress of powering a large fin blade through the water. The result? Fatigue and cramping.

But with the trail-blazing Force Fin^®, our unique foot-pocket design transfers much of the effort of moving the blade to the largest muscle group in your body, the quadriceps, removing pressure from the toes and feet. Because your entire leg is now doing the work, muscle fatigue and cramping is significantly reduced.

And Force Fins^® are the only fins in the world designed to let your toes really breathe, move and wiggle about like they're meant to do. In fact, we've patented this concept, no one else can claim it, no one else can do it. Because of our true, open foot pocket, your toes are finally free!

Natural V-shape
If you've observed fast-swimming fish like tuna, mackerel, jack, pompano, marlin or dolphin fish, you've probably noticed that they all have tail fins - caudal fins - that (1) are relatively small compared to the size of their bodies, (2) are shaped like a crescent or in a "V," and (3) are tall or wide, but short.

These constantly swimming fish are models of efficiency, built for a hunting existence, ranging the ocean and able to swim for miles on end looking for food. By contrast, the slower-moving bass, grouper, rock fish, croaker and snapper that tend to be bottom feeders or grazers and are found skulking around reefs and caves have blunt or squared-off tails.

What is nature trying to tell us? First, fins don't need to be long. Second, the best shape for a hydro mechanically efficient tail that reduces resistance or drag is one that is V- or crescent-shaped and with a high aspect ratio (aspect ratio is the wingspan of the tail divided by its average width); that is, a wider but shorter tail like a bird or airplane wing or fish tail -- or like the blade of a Force Fin^®.

¨ The wrong way (top) and the right way to kick (bottom) The farther from horizontal the feet go when resistance they encounter because of improper body trim and streamlining. When the fins come out from behind you, they slow you down like the air brake flaps on a 747 jet that's just landed. Fighting this increased resistance requires more energy; you're just working against yourself.

Better propulsion than offered by common fins
Divers propel themselves by moving their legs (and the increased surface area of their fins) back and forth against the water with a flutter kick motion. This kicking results in a complex combination of propulsive forces that move the diver forward as well as resistance or drag forces that hinder that movement.

Virtually all of the propulsion comes from the downward phase of the kick (imagine you're horizontal in the water with your stomach toward the bottom) and almost none on the up kick. You can test this yourself in the water by trying to kick up, with or without fins. You'll go nowhere. But simply extend the lower leg down when your knee is bent and watch yourself move ahead.

One reason for this uneven propulsion is that humans naturally have more strength when kicking down. The power or downward phase of the kick emphasizes the powerful quadriceps muscle group at the front and side of the upper leg. The kick's upward phase uses the weaker hamstrings at the back of the thigh and is mainly a recovery movement setting up the leg for the next power phase. The result is a natural two-stroke kicking cycle of power and recovery for each leg. It's the same with other continuous activities like running, bicycling or swimming where a power/recovery cycle is built-in to conserve your energy.

¨ Efficient two-stroke cycle

While most other fins make you work just as hard on the recovery as on the power phase, Force Fins^® take advantage of this two-stroke cycle and work in harmony with the body's natural strength. The flexible blade of our Force Fin^® opens out to its maximum surface area to move a high volume of water during the powerful downward portion of the kick.

At the end of the down stroke, the blade snaps back to its original position, driving water behind at a high velocity and catapulting you forward while at the same time resetting and helping to recover your leg upward for the next downbeat.

During the recovery, the blade folds down, channeling water behind while limiting resistance to conserve your energy. (If you have to put the same amount of energy into both parts of the kick, you fatigue much sooner.)

Force Fins^® are the only fins that provide propulsion consistent with your natural two-stroke kick cycle to this degree. By providing for more of a separate power and recovery phase, oxygen depletion is reduced, and the onset of fatigue is delayed. The result is that divers can kick continuously for longer periods of time.

How Force Fins® work
As you kick down, the blade pushes against the water engaging muscles of the whole leg and providing initial forward thrust.	At the end of the down stroke, with its blade bent back, the fin recoils to its original position, providing additional propulsion and setting up the recovery.	The fin then rebounds to help begin the upward recovery phase of the two-cycle kick stroke.	The fin's tips fold inward to aid the upward recovery and to prepare your leg for the next downward power stroke.

The man behind Force Fins ®
Bob Evans of Bob Evans Designs, Inc. in Santa Barbara, California is always looking for ways to incorporate his observations of the natural world in his fin designs. His Force Fins line is an excellent example of Mr. Evans' creativity and knowledge. Shown below, Mr. Evans demonstrating some of his recent and past experimental prototype fins at DEMA trade shows in 1998 and 1999

View a streaming video of Force Fins ® in action!

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