The Navy SEAL Physical Fitness Guide 75
" If your ankles are inherently flexible, short fins may be more efficient as well
as less stressful on relaxed ankle joints." Your natural kick frequency will also influence your choice of fin stiffness
and size. Larger sizes and stiffness produces a slower rate of kicking, while
short 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 susceptible
to cold. If it is too loose, energy is lost in the slop between foot and footbox; slop also
translates into foot chafe! Booties provide grip for the foot within the footbox and the
neoprene acts to even out areas where stress is concentrated.
Other Fin Selection Considerations
Fins vary slightly in buoyancy; about half of sport fin models float and the
remainder sink. This may be an operational consideration. In the April 1996 Rodale’s
Scuba Diving fin test, fins testing as "outstanding" in the area of power included the
expensive Scubapro Gorilla, Mares/Plana Avanti, Ocean Edge Spectra, and the U.S. Divers
Blades. However, so did the IDI Frog Foot and Power Fin models, which have been the
standard fins in the Teams for many years.
The authors of the article reveal honestly that, "In spite of extensive research and a
multiplicity of designs applied to modern fins, there are still tried and true fins that perform
as well as many of the top newer models." The older, buckle-style strap fasteners have the
advantage of being reversible and are far less likely to foul in fishing line or seaweed than
fasteners on newer models, many of which have quick-release buckles. The simple straps
on older models have no plastic to break, are easy and inexpensive to replace, and can be
found 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. You
should not only consider characteristics of the fin, but know your own physical attributes
and any particular operational constraints in making your decision.
When buying fins consider:
" Size, stiffness, weight, buoyancy, buckles and releases.