Most parafoils are open-celled all along their leading-edge. Water parafoils are closed-cell along the leading edge, with two or so intake openings to allow wind pressurization. Often these openings are valved, with flaps or sleeves to prevent back-flow.
SkySails and various water parafoil trainer and race kites share this special feature. Not only is kite flooding less likely, but the wing takes becomes a cleaner better airfoil. Much like an LEI, the kite somewhat rolls on the surface to orient for launch. So why are such water parafoils so rare, and have not taken hold on land?
Open-face parafoils are simply much easier to fly when water is not part of the mix. They inflate and deflate very fast for versatile operations in complex terrain, where a valved parafoil gets mired misfiring, and must be set up carefully to inflate, and can’t just pop-up or pop-down, and kill almost instantly. They are slower to pack-up, to get the air all out.
This mixed picture is a piloting opportunity, to master the valved parafoil onshore, where others do not. SkySails is in fact undertaking just that. kPower is flying a Pansch Adam valved parafoil in its quiver for some years now. Valved Morse-sled and parafoil pilot-lifters are future kite design directions.