[Paddlewise] "Why do rocker and carving work?"

Ken Rasmussen


kayakfit_at_fidalgo.net


www.kayakfit.com





    Carving is usually like a ski, except opposite.  If you tilt your ski to
the right, it carves to the right.  If you tilt your kayak to the right, it
carves (usually very weakly) to the left.  The effect of tilting the kayak
dramatically increases the rocker, and makes it easier to turn in either
direction.  The carving effect is usually weak enough that one can easily
overpower it, and turn in the opposite direction, if desired.  The amount of
carving force exerted by the kayak depends upon the design and ballasting.
Occasionally, one comes across a boat that carves backwards, i.e., turns in
the direction of lean.  


    I attempt to explain carving by observing that when a sea kayak of
commonplace design is leaned hard to the right, the curvature of the right
side is forced into the water, and the curvature of the left side is lifted
out of the water.  Consequently, the asymmetrical form of the boat tends to
glide through the water following the left curving, right edge of the boat.
Once the turn is initiated the water pressure along the outside edge of the
boat increases, which causes that edge to exert even more control over the
turn.  I think that is why one can do a reverse carve so easily--once the
turning direction is established, the outside edge is pressurized, and the
inside edge isn't.  If the inside edge isn't pressurized it doesn't matter
much if it has the greater curvature.





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