Doug, P18-2,

You want your crossbars water tight?

Usually, there are so many lines inside the front and REAR crossbar, that in a capsize, they drain out equally as well.

NOt using the inside of the crossbars for things like trap bungees, downhauls, barberhaulers, reaching lines (aka chicken lines), etc. is a huge waste of potential space.

My Nacra 6.0, that I bought from a rigging shop owner in the area,
had the barberhauler all internal, where on a jib, you didn't have to do anything, it was on or not.
With the spins I ran though, it was NEVER used, only without spins and going deep, or Really light air.