I purchased an Ericson 29 last spring. It has a recirculating tank. First I had seen of this type. However, there is not a lot of room under the forward berth so it seems to work. The tank has a 15 gallon total capacity. You start by filling it part way with chemical and water which is supposed to keep the recirculating fluid smelling fresh. It works mostly as specified. Haven't yet found out just how long I might stay aboard before a pump out is required but I think it would probably do a couple of weeks anyway for a couple.
I have and Ericson 29. Just bought her. The fellow that I bought her from has the head draining into the drink - no holding tank. Any 29 owners out there with possible solutions?