Probably from what most people see on the water everyday, (wedding cake
boats) you should be able to put almost anything as high as you want on top
of the highest deck on the boat and be ok. We see it all the time.  The old
addage was " one pound up top is equal to five pounds of ballast". I'm sure
it depends on the distance from the center of gravity as to the  ratio of
topside weight/ballast but the axiom still applies. Most fiberglass
production boats are built as light as possible, not only for better
performance but because raw materials are expensive. Lighter does not
neccessarily mean less stabe, I happen to like lighter, it's cheaper to
operate and faster for the same amount of power input as a heavier identical
hull. However, lighter boats are more susceptible to destabilization from
added weight, especially from weight added farther from the center of
gravity. 1000 lb's of batteries in the bilge might make the boats motion
much faster but 200 lb's on the upper deck will make it's motion much
longer, and 1000 lb's up top will make the motion so long that recovery may
be unlikely befor the next wave hits. There's a fine line between being an
easy roller and a crank, I'll take the crank everytime.

-----Original Message-----
From: bob england:
lighter boats are more susceptible to destabilization from
added weight, especially from weight added farther from the center of
gravity. 1000 lb's of batteries in the bilge might make the boats motion

much faster but 200 lb's on the upper deck will make it's motion much
longer, and 1000 lb's up top will make the motion so long that recovery
may
be unlikely befor the next wave hits. There's a fine line between being
an
easy roller and a crank, I'll take the crank everytime.

REPLY
???  Okay, Ill bite.  What do you define as "crank"?
Arild