In contemplating sailboat design I think I have found a fundamental flaw,
that when corrected should yield a great improvement in sailboat
performance.

The flaw is that the keel is put before the rudder. I believe this legacy
continues in modern designs because of accident.

The rudder rightfully belongs in front of the keel, not behind it for
reasons that shall become obvious upon further reading.

Firstly, think of cars and motorcycles. Are they steered by rear wheels?
Mostly not and with good reason, the steering is better done by the front
wheels.

In making a turn, the front mounted rudder would direct an increased water
flow to one side of the keel which would increase the effectiveness (lift)
of the keel - keep the boat upright , the sails would have more power, the
boat less leeway and the turn executed much more quickly.

In heavy seas, the forward mounted rudder would provide greater stability
and control because of its beneficial redirection of water to one side of
the keel.

Docking and tight maneuvers would also be much easier because the bow is
steered, rather than the stern.

Under power, the propeller would be many times efficient. The rudder would
not be blocking the thrust of the propeller nor inefficiently redirecting
it.

The rudder could be configured to alter the characteristics of the bow wave
which would increase the hull speed and overall speed of the boat.

Just like railroad tracks are the width of a horse's ass, rear mounted
rudders are the result of the legacy of dry helmsman. In these modern times
it's very practical to put a rudder under the bow and enjoy the increased
performance benefits.