The short answer is that canards are destabilizing. Not that a vehicle is unstable with a canard, it's that all other things being unchanged, the vehicle will become less stable. To add a canard, the CG must move forward to maintain the same stability.

However, if you were to combine a moving canard (hinged) with a heading hold gyro, you could have a system where you could tune the pitch attitude of the boat with "elevator" and the gyro would react to any waves or turbulence that would try to lift the nose and flip the boat, and keep the bow rock solid. That's artificial stability, same thing used in fly-by-wire fighters... Just might be a challenge getting the gain set right. Worth a shot.