Originally Posted by thorcat
Had a friend with a mono hull
in the marina just down from Kangaroo Point, which is badly affected by ferry wash. He hoisted a 40-50 lb weight and secured it to the top of his mast, seemed to dampen the rolling significantly . Didnt make any sense to me, you would think it would make it worse.
But i saw it in action when the ferries past and sure enough when all the other masts where bouncing around nearly hitting each other, his boat was sitting there relativaly calmly. Might be worth a try. You would want to secure it pretty well thou or it could do some damage.
I think it was Dockhead who corrected me on my false physics that 100kg of mast and rigging
should have little effect on stability compared to a 3000kg keel
(in the context of rig loss).
With my new Cruisers Forum updated physics brain I can take a stab here.
As the radius of gyration increases, the moment of inertia of a the mass will increase by the square of the distance that the radius of gyration increases.
Example: If two rolls have equal weights, but Roll 1 diameter = 1 inch and Roll 2 diameter = 3 inches, it will take 9 times more torque to accelerate the 3 inch roll than the 1 inch roll.
So while it slightly raises the centre of gravity and makes it fractionally more unstable in respect to capsize
the weight aloft is REALLY hard to move so passes force onto standing rigging
and dampens motion in waves.
I remember reading about old ships putting cannon balls up in their rigging and never understanding this concept