Looking for some advice on a backup for an upcoming dive trip. The issues are that the trip will cost several thousand dollars in airfare plus a few more thousand for the liveaboard, etc. The upshot is that I do not want to miss a day of diving nor do I want a chamber dive! I have been using an older computer (Suunto HelO2) in gauge mode as the backup to my Petrel, and that works pretty well. The big problem is that IF the Petrel goes down, I can't get the Suunto out of gauge mode for 48 hours. Diving strictly tables is not the way I want to spend the dive trip so I am looking for a real back up computer that is compatible with the Petrel in that it would run on either the Buhlmann or VPM models. The computer doesn't need to have full trimix capability nor does it need more than a two or three gas capability. Ideally, it shouldn't lockout if I don't follow its profile. (If I use the Suunto as a full backup, I might as well take a sleeping bag to wait out the deco stops.) I am looking at this as an insurance policy for the trip. I would welcome any ideas.