Has anyone tried installing a gyroscope in the form of a water-filled
disc under the bridge deck of a catamaran to reduce the possibility
of a capsize ?

Having a large wave hitting a catamaran is like lifting up one end of
the boat while letting the other end drop until the weight of the mast
and the bridge deck cause it to capsize.

However, a heavy gyroscope spinning at a very high speed under
the bridge deck can cause the boat to defy gravity and stay upright
with a large portion of it hanging in the air until the wave has passed.

And when the storm is over we can just let the water out of the disc
to reduce the weight.