For the Potter, I think either a propGuard or a standard DoelFin (sold
at KMARTS) would keep the rudder out of the outboard. I would shy away
from a "link to rudder" arrangement because you may need the
"hard-over" ability of the motor by itself to turn on the centerboard in
tight quarters.
I steer with the rudder, but keep the motor tight enough to not move
except with some force as in an emergency. An example was at 4:00 AM
several years ago, I was headed out of S/Barb to Santa Cruz Island, went
below to stow stuff, rudder slowly fell off and when I came up, my next
sight was the breakwater 30 feet dead ahead! Rudder AND motor went hard
over in record time! (Murpheys' Law).
A homemade version would be a piece of PVC with brass snap hooks at
ends, and eye hooks on engine cowling and on rudder at stern rail for
QUICK release.
My thoughts only . . . .
Larry Steffen, Monterey Bay, CA
YUUKI HMS 18 #35