Chapter 10: Rudder Geometry, Shape, and Size
Figure 10-15.
Effective rudder
angles at different
points during a
turnand at different speeds. In every case—as we
discussed earlier—the rudder kicks the stern
outboard (to make the turn), and the boat
effectively pivots about a pivot point that is
well ahead of the boat center. Indeed, on fast
planing craft, the effective pivot point may be
ahead of the boat itself. This puts the entire
boat outside the nominal turning circle.
Figure 10-15 shows how the skid changes
the effective rudder angle, even with the rudder
actually held at the same absolute angle (in the
case of the drawing, at hard over, 35 degrees).
Given these realities, the standard meth-
ods in Chapter 11 for calculating water force
on the rudder are good practice and give con-
servative results.