I am sure there is a point where the polar falls off a cliff, however I
doubt you would ever get enough water in!!

Flying older generation gliders like a standard cirrus with winglets retro
fitted, they climb exceptionally well and carry water very well also. The
day has to be pretty crap (2 knot climbs) for me not to carry water!

In newer generation gliders which already have a higher wing loading, I
think it is much harder to call!

JC
Standard Cirrus 566 (UK)