Most manufacturers do not recommend long term storage or low temperature storage -- it may affect the cured property or strength. Some builder find that not much change after accidentally freezing the epoxy, but please check with the manufacturer before building a whole boat on frozen epoxy.
I have,in my past, frozen my brush or roller and reused them the next day. It looked OK, but committing frozen epoxy to build a whole boat is different.

: hey, thought I'd make a post about my findings... I mixed up about an once of
: west system slow epoxy, and put it in a container so there was about a
: quarter inch sitting in the bottom, and I threw it in the freezer. it has
: been in there for a week now, and I went to check it. At first I thought
: it was fully cured, because I could crack it. but to my surprise, after I
: warmed it, it became liquid again. so I guess west system freezes solid
: "or atleast solid enough to crack" My aplication for this will
: be with fibreglass tape. I will wet it out then freeze it. after it has
: been frozen, it will be stiff and not tacky. "I'm going to make ribs
: for a SOF with kev carbon ribs"

: any one else tryed this with faster setting epoxy's? or other brands? I want
: to know if all brands do this. I may want to use a different brand of
: epoxy for my boat.