I have two questions regarding the Oday 28. With the 2QM15 engine is there a special fitting for directing the jacket water to the potable water heater? If so does anyone know what it is called, or is it a matter of using a longer hose off the engine and then daisy chaining the water through the heat exchanger and then back to the engine? It is a fresh water boat, does the jacket water go to the water heater and then to a heat exchanger before returning to the engine? I do not know if the engine was OEM for the 1983 28 footer. My other question is does any one know if there is much of a difference in interior space between the 28 and 30? Thanks