John,
I have worked in water situations for almost 25 years. I would say that on average my tripod and view and MF gear (now DSLR), spend on average 75-80 days a year in wet areas with 1-3 feet of water (sometimes more). I have always used gitzos, but not the carbon fiber gitzos. I tried CF gitzos but I prefer my old metal gitzo tripods for water work. It is a nightly job in my motel room or tent to unscrew my tripod legs and dump water out of the leg and brush off grit. On average, with this care a gitzo lasts 12-15 years before there are thread wear issues with the locking collars or threads on the legs.
I work in both fresh and saltwater.
I don't know if using the CF tripods will present any other issues for you. But my regular old gitzos have held up very, very, well in water useage.
Lyle