Hi Siam,

I guess that either south Australia or northern Europe have more UV intensity. I stored my carbon mast outside and up, however it was the first season. One neighbour is storing his A-cat mast up and outside as well, for some years now without any but cosmetic problems. As any organic material, any gelcoat will be harmed by UV radiation. But this is not realy a show stopper for carbon masts, because there are solutions:
At the begin of the season I put wax on it to protect it. More consequent would be paint or this scotch film stuff, that car builder use to protect their new cars.
Have fun with your new boat.

Cheers,

Klaus