Accepted Answer

If a boat had enough weight, far enough below the waterline and it was wide like a catamaran it's theoretically possible that if you loaded up people on one side, you would run out of space along the rail on the upper deck before the boat capsized.

There was a case in upstate NY a couple years ago where a sightseeing boat capsized just because the people on the lower deck, it didn't have an upper deck, all moved to one side at one time.

If you look at a ferry boat it will illustrate my first point. You could put people on every inch of one rail and in most cases it wouldn't do much more than cause the boat to list slightly to that side. The buoyancy of the hull is compounded the further you get away from the centerline. A narrow boat doesn't have as much buoyancy along the outside edges of its hull.

The most likely place you'd see a dangerous situation like the one you describe, would be on a vessel where someone built an upper deck onto a hull that wasn't originally designed to have one.

Because all passenger carrying vessels in the US must be inspected by the coast guard, it's highly unlikely you would find one that could not meet the testing required for this very issue. This is not the case in other countries. There are loads of stories about relatively large ships capsizing due to overcrowding and it's often on multiple decks.

the answer to the question is yes, a boat could capsize due to too much weight on one side on an upper deck. To further clarify, there are some that would not.

Expert:	ProfessionalBoatGuy
Pos. Feedback:	100.0 %
Accepts:	1
Answered:	10/8/2009

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