all, has anyone replaced their holding tank? I imagine most Catalina's have oddly shaped holding tanks (read not nearly square) like my C28 as they try to get them as big as possible out of the way. I want to replace my black tank with opaque poly(won't even try to spell it). I have no inspection port and would rather just be able to sneak a look to see if it's getting full rather than holing a port into it and adding a tank monitor. The size is just so wierd. it's under the port seat and is 11" high on the cabin side and 4" high on the hull side tapered between the 2 heights to fit into the hole. Any idea where I can get a new one sized correctly? Mike Elmore Windward Hull-C28 Hull #7