The moment of inertia for roll is so much smaller than for pitch, that the roll would be dampened, and the pitch movements wouldn't be too drastic (flat water, small ripples, mild chop maybe)

> Last point as it relates to kayaks. Lets assume you did install
> a full ship-steadying gyro. In a kayak, you'd regret it I believe.
> It's fine on a ship that has a nice tall hull to deflect the waves
> that the ship is now cutting through instead of riding up over. You
> don't have that much hull with a kayak. You'd find yourself soaked
> and exhausted, torpedoing through waves instead of bobbing up over
> them.

How fast do you lean to turn?

> Turning would become very difficult as you would not be able
> tip the boat to change water line and effective chine.

> Lastly, if you turned turtle, you'd never be able to roll it
> back upright.

I never said it had to be practical. As Brian Millington pointed out (paraphrase): Some things just need to be tried (to see if they will work at all).