I'm not sure that the full complexity of this question has been fully presented.
I live on board a lot during the winter and have been through this exercise myself.
I have a professionally installed Espar central hydronic heating
system, part of the original build of my boat. This is an extremely useful device, maybe essential at this latitude, but I do not use it 24/7 throughout the winter. First of all, if you run these on normal marine diesel fuel
, they coke up and require expensive service
, so I try not to run mine when there are other heat sources available. Second, they use a fair amount of fuel
, and so are not that cheap
to run compared to electricity.
These systems have a lot of advantages, but they require professional service
, and can be quite expensive to keep up. I just spent nearly $2000 on mine this year, with several futile service attempts and finally replacement of a burner tube, an amazingly expensive part.
So I use the hydronic system while cruising, underway, at anchor
, but I don't run it if I have another good way -- so I usually heat with electricity when I have unmetered electrical
power. 3.5kW of ordinary domestic fan heaters will keep the boat reasonably warm (16 to 18C) as long as the outside temperature is above freezing. That's a 54' sailing vessel with lots of ventilation, which I do NOT plug
up in the winter, as air circulation is really important for fighting mold
In the U.S., I have used reverse cycle air conditioning
for heat on board, and this is a really excellent system so long as the water temperature does not fall below the minimum (I think 4C or something like that) required for the system to work. Depending on the water temperature, you might get 2x, 3x or even more heat per kWH consumed, compared to simple electric
If I were going to heat with diesel fuel 24/7, I might go to a simple pot heater which is not as sensitive to sooting up and which you can service yourself.
For the OP -- If there is enough electrical
capacity available, and it is either unmetered or reasonably priced, and if you plan to be at a dock
the whole winter, electrical heat can be a good idea. You need to run the numbers to know how much capacity you need -- I would guess it will be 5kW or 6kW for that boat, and don't expect to keep it as warm as a house. If you have air conditioning
, can you run it on reverse cycle?
For most full time liveaboards in cold climates, a single
source of heat will not be enough. I have hydronic plus fan heaters. My next boat will probably have a hydronic system which can use as its heat source not only a diesel furnace, but also engine
waste heat, electrical resistance heat, and maybe even reverse cycle AC.
Another approach could be to heat the salon
with a diesel pot heater (the main disadvantage of these is that it's hard to distribute the heat they produce, but they're great for heating
one big space), and heat the rest of the boat with electricity.
In any case, it's a complicated question with a lot of tradeoffs.