"Capt. JG" wrote in message
...

The boat becomes very much more stable, giving it an extremely
rapid natural rocking motion. If this is sparked off by waves,
the boat is all but untenable.

I think you mean "because more *unstable*" right? I'm not sure
what would have been worse... a washing machine with sharp
objects or just an empty washing machine with soft sides. I
think I'd like to avoid both!

No, I meant stable! Take the top weight of the mast off, and the
centre of gravity of the boat drops down, so the righting moment
goes up.

Add to that the fact that the mast's inertia has gone, and the
boat now reacts very much more quickly to any disturbance - then
rolls back and forth, one cycle every couple of seconds.

JimB