I fell in love with Rob's fore and aft break away rudders at first
sight.   While fore and aft rudders on a proa are hardly an
"innovation", nor are break away rudders, watching a Utube of one of the
Proas sailing, it instantly struck me that this is the solution to a
catamaran problem, as well as wonderful leeway device.      The problem
that it appears to be a potential solution to is tacking.  With a fixed
keel, centerboard, or daggerboard, and the rudder at the aft end of the
boat, you are pivoting  about the fixed surface.    With a rudder at
each end, if you steer them opposite, you are in a rotation with the
after end moving to port as the forward end moves starboard at the same
time.  The center point of the rotation may be the same, but the rate
per distance of forward travel should be double.   The low inertia of a
multihull can result in running out of inertia / forward motion before a
tack is completed, and being forced to backwind and sail backward to
complete the tack.  This problem is common enough that some cat sailors
use engine power to complete a tack.

    Of course if you can turn both rudder the same direction they
should do an excellent job of combating leeway.   Having no center
board, daggerboard, or keel, the dynamics of steering change somewhat.  
If the forward rudder is fixed straight, the turning radius becomes
larger because it becomes the pivot point, and you are farther from it,
so making the boat respond to the wheel "normally" might involve some
engineering challenges, and some trial and error.   Efficient well
balanced airfoil shaped rudders go without question.  The real challenge
is to make the rudders operate seamlessly in more than one mode without
being overly complex.

    It's fun to think about, and a great thing to experiment with on
smaller craft like the canoemaran I'm building.

                                                    H.W.