Sorry, missed this
Really, the SUL starts to feel it's being pushed around at about 6-8 mph (Can't be totally acurate as I don't have a wind meter and am not a natural guesser of wind speed
)
I have now got an EXP leading edge and UL down spars so I can fly it in higher winds. It will eventually stretch the sail I am sure, but for now I am happy enough. Effectively I now have a 1-15ish wind range though. Anything more and I would definitly have to consider a vented. I borrowed a vented for Luton Stack coaching and even that was pulling like a train in the 25+ mph gusts!
I think the blast is meant to be just that, a blast to fly, but not a precision instrument, however I am sure I will be corrected if I am wrong