Aluminum Chambered Boats. They went belly up a few years ago. have never run one. They were part of an R&D OTH project with the USCG i think and ended up losing the contract to Safe Boat.
There is (or was) one operating out of a dive shop in Sacto (Double Down, used to be run by Rek Tek.) Pretty well built, as far as I remember. Never looked too close at it, as the group was kind of snobbish. I do know they had problems with their twin Suzuki motors (pair of 140's?) Lost a couple of them at various times.
I was outbid and it just sold for 22k. There should be more popping up for sale, but if they keep selling for that price I think a Willard or Hurricane might suit me better, even though I love that aluminum hull.