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User:Meesier42/Force Fin

Force Fin

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Force Fin is a small US based company that operates out of Santa Barbara, CA. "Force Fin" is a trademark that distributes fins from Bob Evans Designs, Inc. This small company has introduced many innovative designs to the market. Their designs incorporate a few common elements that offer them distinction from more conventional designs. These include: 1) An open footpocket that leaves the toes free to flex and 2)a cast polyurethane material that has flex and rebound properties significantly different than the latex rubber or TPU that most more conventional fins utilize.

The open foot pockets used in the Force Fin designs fit over the bony mass of your instep. Your foot is free to flex and point with each kick, releasing the calf contraction that is the cause of cramping from other fins. This combined with the higher flexibility of fin has been shown to decrease the hyperflexion of the ankle decreasing the range of motion injures that are believed to be a primary cause in cramping.[1]

Force Fins have an unbalanced power/recovery cycle. This utilizes the large muscle groups on the power kick and relieves stresses on the leg during the recovery stroke. Humans, unlike fish, can not generate equal power on the down stroke (forward) than on the recovery stroke. The human body is has a much greater ability to generate pressure against the fin during the power stroke than to pull the fin upwards (recovery stroke). "the anatomical joints and muscular power a human uses during fin swimming (hip, knee, and ankle) and body attitude in the water does not allow symmetric range of motion when flexing and extending. This fact leaves fin improvement to increasing thrust in the power phase and minimizing drag in the recovery and transition phase."[2] To take advantage of this physical limitation the Force Fin blade is shaped with upcurved tips. These upcurved tips allow the fin to spread during the power stroke to its maximum effective surface area, while collapsing slightly during the recovery. This collapse of the blade minimizes its effective surface area reducing the load on the human leg, reducing fatigue, specifically on the hamstrings. An independent study conducted at the University of Buffalo evaluated many fins for quantitative comparative analysis. Its worth noting that Force Fins were not included in this study. In the discussion and conclusions of this study the authors state that:

"The transition and recovery phases provide little thrust, and in fact, added to the total drag, and had to be compensated for by an increase in kick frequency to meet the overall thrust requirement"

"It has been reported that curved fins had greater thrust than straight fins. In our work, fins where successive TE segments that progress to 90o to the horizontal produced the most thrust during the power phase...As most of the power was produced during 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. This is due to the flow of water over the upside of the fin and the lower muscular force of the hamstring muscles (hip abduction)."

"Swimming with a rigid fin in the down stroke and a flexible fin in the up stroke may be advantageous, but this type of fin was not available for testing."

"As the trailing edge transitions from the recovery stroke to the the power stroke (or vice versa) the fin loses pressure gradient between the attacking and leeward surfaces of the fin. The loss of pressure gradient reduces the potential for forward propulsive thrust during the transition period... To improve the performance of the fin, the time required to complete the transition should be minimized"


"Fin selection is most often made on the basis of the diver's perception of the effectiveness of the fin. In our studies, the diver invariably ranked the stiffest fins as the best and the flexible as the worst, which did not correlate with the objective analysis of these fins."

An earlier study showed Force Fins to be ~25% more efficient than larger more rigid fins.[3]

Force Fin and Bob Evans Desings, Inc. has been awarded many notable awards. These include a permanent collection in the Museum of Modern Art in New York.[4] Recognized in Time Magazines best inventions of 2002 for the OPS fin design.[5] Los Angles "Hall of Fame" [6] As well as being awarded the "Best of Show for Innovative Products" at DEMA 1999.[7] Bob Evans was awarded the prestigious NOGI award [8] and currently (2009-2010) serves as the president of The Academy of Underwater Arts and Sciences.[9]

Force Fins seem to have a love/hate position in the market. It appears that many diver either detest the fins and claim their function and ability to be lacking. While there are divers that sing glorious praises of the designs. There are a few truly notable names that endorse the Force Fin Designs that include: John Chatterton[10] (the books "Shadow Divers"[11] and "Titanic's Last Secrets" and the History Channel's series "Deep Sea Detectives"[12] are based on his experiences), Dr. Phil Nuytten designer of the NewtSuit[13], Fraser Bathgate[14] of International Association of Handicapped Divers (IAHD)[15], Jean-Micheal Cousteau and the Ocean Futures Society[16] that exclusively use Bob's innovative designs.

References

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  1. ^ http://www.forcefin.com/FF_wisewords/lindsey-study.htm
  2. ^ http://archive.rubicon-foundation.org/dspace/handle/123456789/3936
  3. ^ http://archive.rubicon-foundation.org/dspace/handle/123456789/7480
  4. ^ http://www.moma.org/interactives/exhibitions/1995/mutantmaterials/plastics.html
  5. ^ http://www.time.com/time/specials/packages/article/0,28804,1934259_1934566_1934569,00.html
  6. ^ http://www.forcefin.com/FF_PAGES/FF_wisewords/articles/la_magazine_oct2002.htm
  7. ^ http://www.forcefin.com/FF_PAGES/FF_wisewords/research_awards_index.htm
  8. ^ http://www.auas-nogi.org/bio_evans_bob.html
  9. ^ http://www.auas-nogi.org/officers.html
  10. ^ http://en.wikipedia.org/wiki/John_Chatterton
  11. ^ http://en.wikipedia.org/wiki/Shadow_Divers
  12. ^ http://en.wikipedia.org/wiki/Deep_Sea_Detectives
  13. ^ http://www.nuytco.com/about/phil.shtml
  14. ^ http://www.forcefin.com/FF_PAGES/FF_wisewords/testimonials/Fraser_Bathgate.htm
  15. ^ http://www.iahd.org/
  16. ^ http://www.oceanfutures.org
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Force Fin[1] A Kinematic Comparison of Swimming with Two Different Designs of Dive Fins[2]


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