Hey Y'all

Been wondering for a while why recommendations I've read and seen in
practice indicate that boats on a cartop carrier should have the hull on the
car-side of the rig. Especially with an open canoe it seems like it would
accumulate rainwater. I'm usually carrying a sea kayak, and orient the deck
adjacent to the roof of the car (that is, hull up). Never caused a problem,
but would be happy to know other's perspective on this issue. Is this some
sort of aerodynamic deal?


All advice appreciated,

Bill Rezny