Having a little difficulty with some of the posts suggesting that propane and alcohol is a wet heat. The product of any combustion should be vented to atmosphere to avoid carbon monoxide poisoning.
While propane and alcohol burns cleaner than most other fuels, you still shouldn't breathe the combustion products. While you operate these on the boat in summer while the hatches and windows are open. They shouldn't be operated with the boat closed up, when you are trying to heat it.
The moisture, that is most certainly a product of propane or alcohol combustion, goes up the chimney.
When choosing a heating system, one should consider:
1. Fuel availability.
6. Heating in slip vs underway.
7. Heating when aboard vs off the boat.
1. Fuel availability. From a fuel availability standpoint, it is wise to consider the type(s) of fuel already aboard. If one has a diesel engine
, that fuel is already aboard. If one has a propane BBQ, that fuel is already available. Rarely would firewood be on-board already. If the boat has shorepower or a generator
, electricity is available.
. Diesel has low chance of accidentally combusting. However a spill from a leaking connection is possible. Propane is explosive in concentration and heavier than air so may ne the most dangerous. On the other hand, any propane heated vessel, likely already has a propane BBQ and stove, and should be equipped with a "sniffer" to detect a leak, and solenoid to shut off the propane supply (and a valve) when the heater is not in use. Wood or charcoal may combust if stored too near the heater. Bringing firewood on board risks undesirable insect infestation. Electricity is likely the safest "fuel" to have aboard, as long as the boat wiring
is proper, and a safe heater is used. Alcohol, while burning clean, also can burn invisibly. Many a boat fire has happened due to this (including a dear friends, using a non pressure alcohol stove we sold them). Radiant heaters pose a serious burn risk if one should accidentally come in contact during operation, whereas forced air heaters, not so likely.
On our first 20' boat some 20 years ago, I realized we had:
1. Propane for the BBQ.
2. Gas for the auxiliary and dinghy motor
3. Butane for the portable stove.
4. Lamp oil
5. Wax candles.
6. Arial flares.
7. BBQ lighters.
That's a lot of combustibles in a pretty small space. On subsequent boats, we have taken steps to avoid building floating bombs.
space consumed. If one has a diesel engine, there is no additional storage space required for diesel. Same goes for propane if a BBQ exists. Fill-ups may be more frequent. For wood, charcoal, kerosene and alcohol, this may not be so, and additional storage space may be consumed. Shore power
electricity consumes no space.
4. Cabin space consumed. Every kind of system will consume cabin space. Forced air heaters are often mounted in remote
storage areas of the boat of lowest value storage, but the ducting running throughout the boat, may be through high value storage areas, like under settees.
Radiant cabin heaters consume a lot of highly valuable real estate in the cabin (especially when including the minimum clearance zone around them).
spaced consumed. For diesel and propane, this is usually none (as no additional fuel storage space is required if the fuel already exists aboard. However, radiant heaters require a vent coming through deck, that is usually unsightly, may catch on lines and sheets
, and may be a toe stubber, shin scraper in the summer.
6. Heating in slip vs underway. A few years back we were hired to consult a new liveaboard
(Ontario) on heating options. As soon as it was ascertained that heat was not desired when away from the slip, electric quickly became favoured. (Installaing a generator
solely for winter heating, would be cost prohibitive.) We installed a 30A shore power
system to handle normal boat electrics, and primary 1500W electric kickspace heater. We installed a second "deep winter" 30 A shore power system to handle the bilge
heater, two bubblers and a second kickspace heater. (This took advantage of the marinas
shore power offering of 30A year round charge plus a secondary "deep winter" shore power charge.) Most other heating methods can be used underway, which if desired, eliminates electric heat (unless the vessel is equipped with an AC generator.)
7. Heating when aboard vs off the boat. This gets very tricky. For a winter live-aboard, the heating system must operate all the time to prevent freeze-up, perhaps for several days. This eliminates wood and charcoal for sure. I do know some who have left forced air diesel heater for extended periods. Most marina and vessel insurance
policies will prohibit leaving portable electric heater unattended. For this purpose, permanently mounted electric heating becomes very attractive. (If leaving the boat for extended periods, it is wise to have a slip neighbour in a winter live-aboard community ready to start and keep running your potable generator in the event of marine
8. Ambiance. There is no doubt a fire is a heart-warming visual. Our current
boat is equipped with a forced air diesel heater. When we want a romantic atmosphere, we light the "Crackling Fire" DVD
. Insulation is helps to reduce heating costs, and prevent condensation when moisture laiden air contacts walls. Any hatch
metal frames will drip like crazy, as will the ceiling above sleeping areas. There are all kinds of commercially available insulating materials. Metal film coated bubble wrap is a great solution for some requirements. Insulated tarps laid on the deck are a low cost solution for winter live-aboards.
For winter live-aboard in freezing climates, a greenhouse is a virtual necessity. This also increases living space on nicer days, and prevents vessel access snow and ice build-up.
10. Ventilation. This is second factor in the condensation reduction formula. For winter live-aboards, who don't use forced air systems, we install several 12 Vdc fans to keep air moving thoughtout the boat. It is also important to "open up" all enclosed areas, by installing vents in lockers, under settee and berth upholstery, and the head
. (Nothing worse than a chilly seat.)
Full Disclosure: I sell and install vessel HVAC
systems. This post is offered as friendly advice and is not intended to solicit business.
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