A heat pump only works when the sea water
temp is > 40F or so. When it's winter they don't work.
On our cat, I heat it at the dock with 2 x 1500 W heaters; one in each hull
. But that's for working aboard, not living aboard
and it is not enough Watts on a day near 32F / 0C.
My plan for living aboard
is a single Dickinson
"Antarctic" in one hull
, a hot water coil inside the heater, hose to the opposite hull, and a small fan forced radiator. And a circulating pump. The computer fan on the radiator won't draw much, but the circ pump will be at least 1 A. The saloon
is the warmest part of the boat from solar
heating during the day. A fan blowing warm air from the saloon
into the hulls isn't very workable IMO. This is a much simpler, cheaper, and more electrically efficient system than an Espar/Webasto system.
Friends of ours live aboard at a dock in Annapolis
, MD on a St Francis 44. They use oil
filled radiators in the hulls and move them around from saloon to bedrooms as the need arises. They don't try to heat the whole boat.
is very important in preventing condensation
inside lockers that will ruin clothes, food
. We lived aboard in Annapolis
for 3 winters and every year more lockers got insulation (closed cell foam glued to the hull mostly)