Heating options for Cape Dory 27 Sailboat

[Rob S.]

The spec sheet (for the Espar Airtronic D4 in this case) at an output level of 6800 BTU per hour, which ought to be more than enough for a 27 footer, says electrical consumption of 1.1 amps.

If I understand correctly -- and the reason I am posting this is to check -- a typical marine deep cycle battery could have a 100 amp hour rating, so it could run the heating unit for 99 hours continuously (and in most cases it would not be needed continuously) assuming nothing else was drawing on the battery.

This doesn't sound too bad to me, as that amount of draw can be replenished easily with even a modest solar recharging system.

The spec sheet says diesel consumption at that setting is 0.25 litres per hour. Sound pretty damn efficient for both electricity and fuel. I've seen some posts from existing boat users about the electrical demand, so what am I missing?

[mitiempo]

Originally Posted by Atcowboy

........I feel I am leaning towards a parking (torpedo) heater. 5kW, so I have some head room if I end up hanging around New England in the fall. I feel pretty confident I can find room for the unit without much sacrifice in space. I don't envy the extra complexity it will add to the boat, but they do seem fairly simple.

- AT

If you install a forced air heater - Espar, Planar, or cheap Chinese - install it aft in a cockpit locker. Run the exhaust through the transom - the only logical place on a sailboat that is sailed. 2 outlets should be enough for a 27' boat.

I am doing the same on my CS27. Installing a Planar with a 4" outlet. Reducing that to 3" at the heater, running that to the cabin and through a reducing "Y" with 2 outlets each 2 1/2" and then to 2 adjustable heat outlets in the cabin.

[manitu]

Finding the space for a small reflex/dickinson heater in the center of the boat seems like a difficult task..

If battery capacity or regular charging could be a problem, you should check out the wallas 22dt or 30dt heaters. They are more expensive than their chinese counterparts, but use one third of the power. 0.9amp max.
The price difference is'nt as big as it seems , as a proper exhaust for the chinese heater cost at least as much as the heater.

Their new 22gb and 30gb versions run on about any diesel-like fuel.
Autodiesel, Commercial boat light fuel oil, kerosene , HVO , B10/20/30 biodiesel blends..

.manitu

[Atcowboy]

Originally Posted by Rob S.

The spec sheet (for the Espar Airtronic D4 in this case) at an output level of 6800 BTU per hour, which ought to be more than enough for a 27 footer, says electrical consumption of 1.1 amps.

If I understand correctly -- and the reason I am posting this is to check -- a typical marine deep cycle battery could have a 100 amp hour rating, so it could run the heating unit for 99 hours continuously (and in most cases it would not be needed continuously) assuming nothing else was drawing on the battery.

This doesn't sound too bad to me, as that amount of draw can be replenished easily with even a modest solar recharging system.

The spec sheet says diesel consumption at that setting is 0.25 litres per hour. Sound pretty damn efficient for both electricity and fuel. I've seen some posts from existing boat users about the electrical demand, so what am I missing?

I think the general concern is that (in my boat's case) two group 27 batteries net around 180 amp hours. Lots written about this, but most batteries in service get charged to like 90% and you shouldn't go below 50% (which is pushing it). That means 72 amp hours available. Say I ran it overnight for 12 hours (all the reviews I have seen about 2amp draw) so that's 24 amp hours.

- AT

[Atcowboy]

Originally Posted by mitiempo

If you install a forced air heater - Espar, Planar, or cheap Chinese - install it aft in a cockpit locker. Run the exhaust through the transom - the only logical place on a sailboat that is sailed. 2 outlets should be enough for a 27' boat.

I am doing the same on my CS27. Installing a Planar with a 4" outlet. Reducing that to 3" at the heater, running that to the cabin and through a reducing "Y" with 2 outlets each 2 1/2" and then to 2 adjustable heat outlets in the cabin.

This is a part that I haven't started researching yet, but I am definitely curious about. What is your reasoning on transom exit? I'd just be worried about the exhaust getting stuffed while sailing.

I'm also trying to follow your ducting. Why are you reducing the ducting at the heater? I would imagine reducing it right at the heater would create back pressure/reduce flow over the heat exchanger. Is it because a 3" duct will be easier for you to route?

Thanks,
-AT

[mitiempo]

Originally Posted by Atcowboy

This is a part that I haven't started researching yet, but I am definitely curious about. What is your reasoning on transom exit? I'd just be worried about the exhaust getting stuffed while sailing.

I'm also trying to follow your ducting. Why are you reducing the ducting at the heater? I would imagine reducing it right at the heater would create back pressure/reduce flow over the heat exchanger. Is it because a 3" duct will be easier for you to route?

Thanks,
-AT

The heater I am installing is ok with the 4" to 3" reduction at the heater. 3" is easier to run. Then reducing it to 2 1/2" with the "Y" to one heat outlet. The other part of the "Y" will be split again I think to 2 separate outlets, one forward in the main cabin and the other in the head area.

As far as transom outlet sailboats heel, sometimes to deck level. One good ingest of salt water and the heater either needs an expensive service or worse. An exhaust in the top half of the transom rising inside before going down to the heater eliminates any water issues.

If you think you need to install the heater farther forward Wallas has a closable deck exhaust that can be used.

I have installed many heaters professionally - work at the Canadian distributor for Wallas. The only situation for an exhaust out the side of the hull is on a powerboat.

[mitiempo]

Originally Posted by manitu

If battery capacity or regular charging could be a problem, you should check out the wallas 22dt or 30dt heaters. They are more expensive than their chinese counterparts, but use one third of the power. 0.9amp max.

Wallas are energy efficient but not that much. The 22GB consumes .7 to 1.2 amps. The 30GB consumes 1 to 2 amps.

The DT models are no longer available, replaced by the GB models. Power consumption is the same but the GB models are designed to use biodiesel.

[nwdiver]

Wall mounted, vented propane.....uses propane but just sits there happily waiting until you need it.

[mitiempo]

Originally Posted by nwdiver

Wall mounted, vented propane.....uses propane but just sits there happily waiting until you need it.

Good depending how the boat is used. If used continually, as a liveaboard would, not efficient. The small Dickinson (P9000) lasts 5 hours on 1 lb of propane, so 50 hours on a 10 lb tank. Then you have to lug the tank to be filled. This is a 4500 btu heater.

Diesel forced air will run efficiently on a fuel which is already there in a tank.

The Wallas 22GB consumes .1 to .22 liters per hour. That's 38 hours/US gallon on low. And 17 hours/US gallon on high. This is a 7500 btu furnace.

The propane heaters are nice, just not the best choice for an every day need for heat.

[alansmith]

The thing that disturbs me much more than cold is the condensation. Can’t abide cold and wet. That is torture. It is Navy Seal trainees worst nightmare. You can always get a rubber bag and put hot water in it for warming up the sleeping bag.

Been an interesting discussion. Last February I was sleeping in the boatyard at San Carlos. It was getting down into the low 40’s at night. No heater. Wore everything I had. Still not comfortable sleep. Never thought it would get that cold in Mx.

[Atcowboy]

Originally Posted by mitiempo

The heater I am installing is ok with the 4" to 3" reduction at the heater. 3" is easier to run. Then reducing it to 2 1/2" with the "Y" to one heat outlet. The other part of the "Y" will be split again I think to 2 separate outlets, one forward in the main cabin and the other in the head area.

As far as transom outlet sailboats heel, sometimes to deck level. One good ingest of salt water and the heater either needs an expensive service or worse. An exhaust in the top half of the transom rising inside before going down to the heater eliminates any water issues.

If you think you need to install the heater farther forward Wallas has a closable deck exhaust that can be used.

I have installed many heaters professionally - work at the Canadian distributor for Wallas. The only situation for an exhaust out the side of the hull is on a powerboat.

Transom mounted exhaust on sailboats is always at risk of getting stuffed in large following seas or a pooping. Water over the lee rail from stem to stern is a pretty common occurrence so yes, side exit is not a viable option. If money weren't something I need to worry about, I would change the skin fitting for my engine to a seacock out of an over abundance of caution.

I'm trying to intake the collective wisdom of the internet for these heaters at the moment and haven't gotten to the very specific aspects of installation. That disclaimer out of the way, I would also say that a high transom mounted skin fitting for any purpose is not likely to get stuffed under most instances. Arguing against myself, I would imagine that dog house exit would be the safest regarding water ingestion. On the other hand, I imagine transom exit would be the least annoying regarding sound to the boat's occupants.

The CD 27 has two 4" intakes on the rear deck for ventilation for the engine compartment. I was thinking one of these could be dedicated to cabin air intake for the heater.

I've read a lot of different opinions on where to get the combustion air intake and think I would like a dedicated source from outside the boat. But I haven't decided where I would like to pull that from.

Do you know of any good articles describing how to go about this?

- AT

[DefinitelyMe]

We've just installed a 2kW forced-air Chinese diesel heater. It's running as I write this. Very happy with it so far. For a 27' boat I really would have thought 2kW should be plenty. The unit is physically smaller than the 5kW, ducting is smaller etc. which should be a good thing for your limited space. Actual measured output is even a little greater than 2kW so performance will be better than that electric heater you're currently managing with.

[mitiempo]

Originally Posted by Atcowboy

The CD 27 has two 4" intakes on the rear deck for ventilation for the engine compartment. I was thinking one of these could be dedicated to cabin air intake for the heater.

I've read a lot of different opinions on where to get the combustion air intake and think I would like a dedicated source from outside the boat. But I haven't decided where I would like to pull that from.

Do you know of any good articles describing how to go about this?

- AT

You don't have to have a dedicated inlet for combustion air. As long as the rear deck vents are there the heater will pull in air.

Heater not likely to be used in rough conditions offshore - just plug the exhaust at that time.

[Atcowboy]

Originally Posted by mitiempo

You don't have to have a dedicated inlet for combustion air. As long as the rear deck vents are there the heater will pull in air.

Heater not likely to be used in rough conditions offshore - just plug the exhaust at that time.

I don't really follow your logic. Cold, wet, miserable offshore conditions sound exactly like when I would want my boat to be warm and dry inside.

The only thing I can imagine that is more miserable than sitting at anchor or at dock in vile conditions is hove-to while waiting out vile conditions. The first two, you may be able to go to shore for a coffee or to walk to dogs at least. I guess hove too, you hopefully aren't as worried about land or other hard objects...

- AT

[Cheechako]

Combustion air should not be a problem, your boat is not air tight, any crack in the companionway hatch or etc will feed it when you have it on.
You may be overthinking that part. I doubt cabin heat will be a high priority when you are hove to in rough conditions. You are more likely trying to figure out if running downwind would be more comfortable?, or a different sail?, or why does the boat keep wallowing? or......
Sailors have been living without heat for that for 100's of years.