Thicker rails are going to be more
forgiving than thinner rails. For the
water to push down on the deck and
destabilize you, first it has to get onto
the deck. Any SUP paddler that comes
from kayaking will tell you that a round
creek boat shaped kayak is more
forgiving than a flattish hard railed
playboat style kayak. The same
physics apply to SUP. An eight-inch
thick rail requires the water to travel
that much higher to get onto the deck
than a five-inch thick rail. And a
rounded deck is going to force the
water to apply the pressure gradually,
rather than the switch like on/off of a
flat deck.
Simply put, a narrower (within reason)
thick-railed board with a rounded deck
rail is going to be more forgiving than a
wider, thinner, flat deck rail.
That said, stance height above the
water is a major contributor to
stability. For every 1cm lower you
stand, its about the equivalent ‘flat
water stability increase’ of a 2cm wider
board, all other design elements being
equal. This is not an absolute, but it’s a
foot as both plastic and inflatable
boards have, nor longitudinal and
torsional flex like inflatable boards have.
Flex in a board amounts to something
much like trying to do yoga while
standing on a waterbed: you might
develop the skills to do it, but it’s a lot
harder than standing on a solid floor.
nice little rule of thumb. Therefore
standing on a six-inch think board
that’s 34 inches wide has the same ‘flat
water’ stability as standing on a five-
inch thick board that’s 32 inches wide.
Clearly, a low standing area conflicts
with a high sidewall rail if the board is
essentially planar in its design (parallel
deck and hull), which all inflatable
boards are. Composite and plastic
boards allow you to recess the standing
area as the design is not dictated by
the construction method, so that you’re
at waterline (or below) and have a thick
rail – letting you eat your cake and
have it.
Centre of gravity
The most stable position on the board
is when your centre of gravity is lined
up with the centreline of the board.
Your centre of gravity is close to an
imaginary vertical pole running down
through the center of the top of your
head, down through your chest
following a straight back, out the
centre of your crotch and down to the
board, landing directly on the
centreline of the board (stringer).
If you’re on an inflatable, then you
have to make decisions between the
extra volume and forgiveness of six-
inch versus the lower standing height
of a five-inch. There is no correct
answer: this is simply information for
you to use.
No matter what your knees, ankles and
legs are doing, the goal is for this
imaginary pole to always remain
vertical (even if the board is not
horizontal) and pointing at the
centreline of the board.
Construction method is a contributor as
well. The most stable boards are
composite as they are the stiffest. They
have no flex at all, either directly under
Main pic: The moment before the fall- bending at the waist throws
your centre of gravity out from both the centreline of the board, and
out from an imaginary line going through your entire body that’s
centred between your feet
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