The Navy SEAL Physical Fitness Guide - Uniformed Services ...

" If your ankles are inherently flexible, short fins may be more efficient as wellas less stressful on relaxed ankle joints." Your natural kick frequency will also influence your choice of fin stiffnessand size. Larger sizes and stiffness produces a slower rate of kicking, whileshort flexible fins allow a higher kick rate.Operational Constraints:" Face down versus sidestroke position." Surface versus submerged." Space limitations (SDV)." Thermal protection.The fit of the fin is critical.If the fin is too tight, the finbox may make your foot cramp up and more susceptibleto cold. If it is too loose, energy is lost in the slop between foot and footbox; slop alsotranslates into foot chafe! Booties provide grip for the foot within the footbox and theneoprene acts to even out areas where stress is concentrated.Other Fin Selection ConsiderationsFins vary slightly in buoyancy; about half of sport fin models float and theremainder sink. This may be an operational consideration. In the April 1996 Rodale’sScuba Diving fin test, fins testing as "outstanding" in the area of power included theexpensive Scubapro Gorilla, Mares/Plana Avanti, Ocean Edge Spectra, and the U.S. DiversBlades. However, so did the IDI Frog Foot and Power Fin models, which have been thestandard fins in the Teams for many years.The authors of the article reveal honestly that, "In spite of extensive research and amultiplicity of designs applied to modern fins, there are still tried and true fins that performas well as many of the top newer models." The older, buckle-style strap fasteners have theadvantage of being reversible and are far less likely to foul in fishing line or seaweed thanfasteners on newer models, many of which have quick-release buckles. The simple strapson older models have no plastic to break, are easy and inexpensive to replace, and can befound in almost any dive store. These fins are also not as slippery on deck as newer designs.As a SEAL, you will need to evaluate individual fin performance carefully. Youshould not only consider characteristics of the fin, but know your own physical attributesand any particular operational constraints in making your decision.When buying fins consider:" Size, stiffness, weight, buoyancy, buckles and releases.The Navy SEAL Physical Fitness Guide 75