I dont know of any on the water tensioning systems on Javelins, I14s, Cherubs or 18teens.. (perhaps 12s or 16teens may have something but doubt it) They are all set and forget..
I suspect because the 49er is a SMOD any change to any part of the rigging is forbidden.. The one design is complete down to the size of the wire one uses for the trapeze wire.. The 49er has set battens ie they slide in and if the sail or batten isnt completely accurate your either up tension or down... What I suspect they are looking at, are either buckles or velcro batten holders.. To allow for inaccuracies in sail plan by the one world sail maker, and or small differences in batten production by the registered builders..

The only system I have seen on skiffs that is out of the ordinary is the batten system one sees on some racing boards.. Its a fixed batten with an allen key that increases the batten length or stiffness.. Definately not easably adjustable from the drink..