Jake,

I suspect that this Mystere is a 1970's 16ft that was a contemporary of the Condor, Hydra and early Dart 18's. In answer I would say that a boat of that age is unlikely to be happy with 145Kgs plus, say another, 70Kgs for the helm. I also doubt that the trap wire could be guaranteed to take that weight and anyway - where do you get a harness in XXL?