Cabin heat from diesel engines

[Boatyarddog]

Originally Posted by UNCIVILIZED

Propane fueled heaters, from what I understand, add a lot of extra moisture into the cabin, as a by product of their combustion. Which you don't, of course, want, when it's cold outside. As such will just magnify the condensation problems which you likely already have, when the thermometer starts dropping.
Where as, diesel heaters, produce a dry heat. And so, aid in managing the moisture issue.

Regardless of which you choose, it's probably worth doing the numbers on installing water heating coils in, or next to/around, your heater(s). So that you can more efficiently spread the heat around your boat. Particularly given that it's a catamaran, which has several different "zones" which will need heating.
That, & look into installing 2+ heaters. One in each hull perhaps, plus possibly one for the bridgedeck cabin.

You can get Refleks heaters with such coils, built in. And there's a little info & feedback on a few different types of heaters, here on Beth & Evans's site Top Rated Equipment

Refleks's website is definitely worth visiting, too. Especially when you consider where the units are made. Plus, their target audience.
I mean guys who live & sail that far North (Professionally), in waters which never really warm up, must know a thing or three about heating boats.

Also, making sure that your boat's well insulated is Huge. To the point where it'd make sense to borrow a Thermal Imager of the sort that's used to check for heat leaks in homes (gratis I think, or for a small fee at most).

When I insullated my 1st boat, the results were giant, & immediate. And it took me all of a weekend to do, with; closed cell foam, 3M Spray Glue, & automotive headliner carpet + trim.

You certainly don't want to vent exhaust of any combustion heater into the cabin space.
Many heaters that use petroleum fuels, or gasses draw air from the outside, as well exhaust to the outside.
If you have any open flame in the cabin, supply a lot of fresh air to the cabin interior.
Also an CO ( carbon monoxide ) sniffer is really recommended.


Sent from SV Cloud Duster

[bix85]

Thanks for all of the replies. Much appreciated! Now, I'm trying to decide about hot water for dishes and showering. A forced air system won't help me there, but is nice otherwise.

Sent from my HTCONE using Cruisers Sailing Forum mobile app

[a64pilot]

Originally Posted by Liam Wald

a64Pilot,
What fuel do you use to cook with aboard your boat?

Propane, and it's on for a very short time, is always monitored and is shut off by a solenoid at the tank. (I put a very bright LED on the switch as my wife kept forgetting to turn it off)
A heater is of course going to be on when it's cold, even at night when your asleep and only rarely shut off at the tank.

[a64pilot]

Originally Posted by bix85

Thanks for all of the replies. Much appreciated! Now, I'm trying to decide about hot water for dishes and showering. A forced air system won't help me there, but is nice otherwise.

Sent from my HTCONE using Cruisers Sailing Forum mobile app

Now I don't know much about heaters, but I believe a system exists that heats the boat with hot water, and provides hot water for showers etc.

[Dymaxion]

Originally Posted by bix85

Thanks for all of the replies. Much appreciated! Now, I'm trying to decide about hot water for dishes and showering. A forced air system won't help me there, but is nice otherwise.

Sent from my HTCONE using Cruisers Sailing Forum mobile app

In that case go for a hydronic system. They can put out a lot more heat than the air units. You'll need to run a return loop back to the "furnace", think PEX tubing. Use automobile heater units, meaning small radiator plus fan. Plumb the whole lot into your water supply system with a branch feed to the HW side. This is called a combi system in the HVAC world. The furnace has a circulation pump, will return lukewarm water from heater units for reheat. Cracking open the HW taps takes water out of the system, but your CW pressurised supply will keep the heating system topped up. Be careful in that automobile coolant systems run around 15psi, your onboard supply may be 40+psi. Pressure test the heater core to at least double your system pressure. In a cat I'd put a large heater unit in the bridgedeck for main output, then use a T-fitting to run to a smaller unit in each hull, then return lines back from each hull to furnace. Complete Webasto Thermo Top C can be bought new for $1000 on FleaBay. Nope, don't work/etc for them.

[S/V Alchemy]

Originally Posted by UNCIVILIZED

Propane fueled heaters, from what I understand, add a lot of extra moisture into the cabin, as a by product of their combustion. Which you don't, of course, want, when it's cold outside. As such will just magnify the condensation problems which you likely already have, when the thermometer starts dropping.
Where as, diesel heaters, produce a dry heat. And so, aid in managing the moisture issue.

Regardless of which you choose, it's probably worth doing the numbers on installing water heating coils in, or next to/around, your heater(s). So that you can more efficiently spread the heat around your boat. Particularly given that it's a catamaran, which has several different "zones" which will need heating.
That, & look into installing 2+ heaters. One in each hull perhaps, plus possibly one for the bridgedeck cabin.

You can get Refleks heaters with such coils, built in. And there's a little info & feedback on a few different types of heaters, here on Beth & Evans's site Top Rated Equipment

Refleks's website is definitely worth visiting, too. Especially when you consider where the units are made. Plus, their target audience.
I mean guys who live & sail that far North (Professionally), in waters which never really warm up, must know a thing or three about heating boats.

Also, making sure that your boat's well insulated is Huge. To the point where it'd make sense to borrow a Thermal Imager of the sort that's used to check for heat leaks in homes (gratis I think, or for a small fee at most).

When I insullated my 1st boat, the results were giant, & immediate. And it took me all of a weekend to do, with; closed cell foam, 3M Spray Glue, & automotive headliner carpet + trim.

All this, plus read "The Warm Dry Boat" by Roger McAfee.

If you have your heart set on scavenging heat from your diesels, a bypassable circuit from your heat exchanger to a block heater and a muffin fan works, but only under motor, of course. Really, it's easier to have a diesel heater and to keep one area toasty. Keep other areas ventilated. Cool and dry is better than cold and damp.

[nortonscove]

We run our heater while motoring to warm the cabin and makes things dryer. It really helps when you arrive in a warm and dry boat. Not playing catchup.

[Juho]

If the weather is not very cold and you want just some heat, then I (like many others) recommend diesel heaters. If the weather is really cold, then I note that heating up a monohull would probably be cheaper and easier than heating up a catamaran, because of its large surface area.

I have considered the possibility of adding water based heating in my boat. The fact that my engine has a closed loop fresh water cooling system, makes it easier to extract heat from the motor. Currently it heats the hot water system. It is very efficient. Using the motor for 10 minutes when leaving the marina gives us lots of hot water for the day. We have a diesel heater too, but in a cold climate it would make sense to capture also the extra heat of the motor, that will otherwise go to the sea, if we motor more than what we need to heat out hot water tank.

But I guess these solutions are for colder climate and bigger heating needs than what you are planning for.

I have considered also storing the heat in paraffin. The idea here is that the melting temperature of paraffin is somewhere around 55°C / 130°F, and that would give me plenty of heat exactly at that nice temperature. The heat capacity of water is higher that that of solid or liquid paraffin, but the nice melting point could make paraffin better. Does someone have an opinion on this?

[Striker37]

Here in florida it did get cold for a few weeks one winter.I just run both my diesels till they both got up to temp then shut them off and then opened the engine hatches for a hour.The heat from the engine room heated my boat all night.

[mrmikek]

I had good luck with the Webasto forced air on my other boat. Sailing Puget Sound. I have a friend in Seward that is using the Webasto Hydronic system and likes it well.

[Jack Sanford]

I have been cruising the Maine coast for over 40 years, and highly recommend a diesel heater (Espar or Webasto). When we have installed ours, we run a duct to the head, as well as the main cabin. Locate the thermostat by the your bunk so you can shut off the heat at night, and turn it on again before you get out of the bunk in the morning. Your crew will love it.

[alctel]

I have a diesel dickinson bulkhead unit. Does a good job heating and the flame is a really great touch - just watching it warms you through and through

[tstano]

Well there is this place called LL Bean in Maine. Buy a jacket. Cheap, reusable, no electronics, no CO. look like a Mainer. When sailing there is no such thing a poor weather, just poor choice of clothes.


All U Get

[bix85]

Great replies! Thanks to all. I'm trying to digest it all. Tstano, I'll definitely get a good jacket.

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[sailor1924]

My current boat has a Sig 170 bulkhead mounted diesel heater that supplies 14,000 btu per hour at high setting it draws a tiny amount of power for a small dedicated fuel pump. It does a good job in the NY winter. I have a radiator system and a fan to scavenge heat off the exhaust stack. I also have a bus heater plumbed into the engine cooling system that will furnish cabin heat when the engine is running. The engine also will heat the domestic water heater as well.

On my last boat I had a slightly larger Sig 180 and I made a water coil and installed fin tube radiators under the cabin sole the length of the boat, warm feet were great! I had a demand tankless propane water heater made in Germany that required no electricity only the low pressure water system to control the flow of propane, there was always hot water for showers, the only problem I had was making sure the water wasn't scalding hot.