Heating System for My Multihull

[bobconnie]

All we can say is Hot water heat is the only way to go if ya want warmth and a Dry interior. No matter how ya heat the water, you can move it and regulate the temp so much easier!! with proper temp diodes you can control each and every area on your boat !! Less loss of heat then with duckted forced air! and less noise and less power to operate!! All ya need to worry about is insulation !LOL Hot water heat worked for us in the winter time in alaska a couple or three winters in a steel boat!

[Palarran]

I don't have the spec's but if you figure a heat pump needs to absorb between 10 and 15 degrees of heat from the water and therefore the refrigerant temp needs to be about 10 degrees below that, you will ice up the heat exchanger. What temperature does seawater freeze at?

We do closed loop ground water heat pumps regularly and they pretty much become ineffective when the ground temperature falls below 25 degrees. The water temp going out to the loop is only 5 to 10 degrees.

In any case, you would have to run the generator to run the heat pump, burning diesel that would be more efficiently used with a diesel heater. I'd also guess that since the air will be hotter from the diesel heater it will also dehumidify the boat better.

[BambooSailor]

I installed ESPAR 32000 BTUs hydronic heater on my 41' cat. 4 fan heaters in each cabin + 2 for salon/galley, all individually controlled by digital thermostats. Installing supply and return tubing was a challenge because of space and accessibility constrains. I used PEX tubing and built fan heaters using remanufactured heater cores used in cars + 2 computer fans/per core. Works very well. I can heat my boat to 80-90 degrees (or more - but never tried) in freezing temperatures. Condensation on cold, not insulated surfaces (e.g. below waterline or windows) can be significant, though.

[webejammin]

We installed a Dickinson Newport Propane furnace/ fireplace 1200 and love it. If your catamaran is big I would recommend one in each hull. On our Gemini 105Mc it only takes one unit to keep it warm at 32F on the hook. At a price of $850.00 US thru Fisherman's Supply, not a bad price for clean heat and the install was easy. We use a std propane bottle and it lasts 5 24 hour days at least. The double walled intake and exhaust pipe can be run thru a plexiglass window and mounted on a vertical surface so no cutting thru the deck.