After reading sources recommending 795 for bedding things like acrylic to aluminum or fiberglass (ie hatch lenses or skylights) I tried it on our hatches and skylights about 3 months ago. I didn't do a particularly swell job of cleaning out the old stuff (the hatches mounted on a strip of rubber I left in tact) but so far no leaks, and the acrylic hatch bond to the frame is strong.

I can't speak for its long term set, but have read good things about it as Westcoaster attests.