Ewest, The part that isn't covered is just bracing. When the barge is connected on the end of the ramp there could be alot of wind/wave pressure against the ramp/barge combination. I wanted an eight foot base rather to four feet to handle the pressure.
I could have covered it, but that would have meant more joists to install and more plywood. A 4 foot wide ramp is wide emough for me.
