Kent, this is one of those problems that, if you
have to ask, it can't be done. I don't know how the 33 is set up, but if the bottom of the ice box is anywhere near the waterline, your out of luck. I've never seen a box that wasn't. On my 34, I built a freezer next to the refer. (ice box) Both are cooled with engine driven holdover plates. I hooked the drains to a common hose and led it past the bilge to the shower sump. I did it for several reasons that I won't get into here, but the big reason was ease of cleaning the sump vs. the bilge.