Ted, I appreciate your reply, as well as the abundant comments already provided. I have read the continuing threads on this topic with rapt interest, but have been on the hard with family issues to respond. After reading and viewing the info provided, I did more research.
I called Dickinson to talk to their product experts about some of my installation issues. Harmony is a WS42 ketch and the location of the mast, forward salon bulkhead, and staysail track are important data points. My favored tack has been a diesel heater. The Dickinson models require a 5 inch hole in the cabin top for the 3 inch chimney to exit. Harmony's prior owner had a cabin heater and there is a 4 inch hole in the deck, but no heater. This 4 inch hole is just forward of the staysail track and just aft of the forward salon bulkhead. For me to install a 5 inch hole, I would intrude into the sail track and the bulkhead. Unfortunately, Dickinson's experts weren't able to provide a suitable work around for a 4 inch chimney hole: the 5 inch hole provides a 1 inch gap for heat dissapation on the 3 inch chimney. I guess the 1/2 inch gap is too small for their comfort and, perhaps, the deck's too.
So, a this point I don't have another area into which to direct the flue and drill the required 5 inch hole. Now, I can use the existing 4 inch hole to run the flue for the Dickinson propane heater. Or, I can investigate a new rigging system for controlling the staysail.
If I eliminate the sail track for the staysail boom, I might be able to install a different arrangement for the staysail and then be able to install the required 5 inch flue aperture for the diesel heater. While I have considered a roller furler arrangement for the staysail, I was not rushing into that decision. Besides, these decisions should be mutually exclusive, and I don't want to make rigging decisions because of a heater choice.
I eliminated the Espar type heater because it was way too expensive: $5,500 to $6,000 installed. This system, while seemingly well engineered, takes up a lot of valuable space in berth lockers, too. We are not planning extended liveaboard stays, especially in the winter months. However, we are contemplating a cruise down the ICW a few Fall seasons from now. Most of our heating needs will result from summer cruising in Maine and late Fall sailing in New England.
I am left with 2 options for heaters: (1) install the propane heaters, p12000 and p9000, in the salon and aft cabin, respectively, and deal with the multiple fuels and tank fillings; or (2) continue to investigate how to adequately insulate the 3 inch chiminey of the diesel heater for the salon in order to use the existing 4 inch hole in the deck. Right now, I am leaning towards option (1). However, I do like the simpler fuel situation provided by the diesel option.
One thought I have contemplated is trying to find some sort of insulating ring which would provide a significant amount of heat sink for the diesel chimney. But I haven't been able to come up wtih anything. So, the propane option has the lead until and if I can find how to solve the diesel chimney hole requirements.
Doug