Portable, Temporary Underway Heater

[sailorchic34]

I heard a rumor that a blonde engineer, mounted a little buddy on a bulkhead (it has tabs on the back for that it seems), removed the built-in 11" w.c. regulator and piped the heater direct to the low pressure propane system. Then installed a 8x8x2 draft hood (brownie pan) with 1-1/2" copper tube/ flue through the deck. No moisture, no co2 buildup.

Of course that would totally void all manufacturers warranties.

Note: the older Little buddies were easier to modify. The newer ones are a bit harder to modify. But just a bit.

Either 1-1/2" copper tube or SS pipe would work fine as a vent and is more then adequate for venting 9000 btuh. Vent cap was a 4" dia. 6" long piece of copper with a tin shield shaped to allow gases out, but block rain from getting in.

Deck penetration consists of a round teak block, contoured to remove deck slope with 2" hole and a 2" threaded galvanized and painted pipe flange bolted to it. To that is screwed in a 2" union.

Flashing to make the flue water tight was done in aluminum in the shape surprisingly like that of a 12oz beverage can. Not ideal, but plentiful. The bottom being trimmed out from the center of the can with tabs puched down to allow them to grip flue. 600 degree F High temp gasket sealer keeps the flashing/ flue joint leak proof. A pipe clamp holds the flashing to the union on the deck flange. The flue is removed for ocean passage and a 2" plug screwed into the deck plate (pipe flange).

Or so I heard anyway ...

[Dockhead]

Originally Posted by bensolomon

I respectfully disagree. I specifically use 200 proof grain alcohol which has no water in it. In addition, since it is not "denatured", it does not contain methanol which is what is used to denature alcohol for a fuel use. Therefore, with no methanol, pure grain alcohol will produce zero carbon monoxide and an indetectable amount of water.

Our exhaled breath will produce more condensation then burning grain alcohol. Anything less than 100% pure alcohol, there will be water in it and condensation will be formed.

I think Thinwater already answered this, but the water vapor produced by the combustion of any hydrocarbon has nothing to do with water in the fuel. All hydrocarbons -- alcohol, diesel fuel, gasoline, rocket fuel, whatever -- are comprised of carbon and hydrogen, and produce varying amounts of CO2 and H2O depending on the proportion of hydrogen and carbon in the particular fuel. Ethanol (pure grain alcohol) is C2H5OH. So ideally combusted ethanol will produce 3 parts water vapor to 2 parts CO2, by mass. Burning alcohol produces a damp mess in the cabin of an insufficiently ventilated boat.


And the takeaway from all of this is that it is extremely undesirable to let the products of combustion of any fuel into the cabin of a sailboat. You will get some or another proportion of CO, CO2, and H2O -- NONE of which you want in your cabin air.

[thinwater]

Originally Posted by Juho

If one connects some additional elements to the stove, the idea could be to move as much of the heat of the stove to the other elements of the boat (via radiation and via the heated air). If one sees it this way, I guess metal parts (cooling fins) and fans (maybe heat driven stove fans) would be the most efficient solution. Clay pots might not be ideal, but maybe useful still (don't know about their heat conductivity etc.).

Clay may not be the best way to store heat. When I have wondered how to store heat in the boat, my best understanding so far is that hot water might be the best substance for storing heat (to keep the boat warm overnight). Also the properties of paraffin wax seemed interesting, but water has the advantage that you can (at least in principle) take the water from the sea/lake when you need it, and also pump it overboard when you no longer need it, and the extra weight in the boat.

Do you have any expert's comments on what would be the best way and medium to store (and distribute) heat inside the boat?

Google "specific heat" and you will see that hot water is probably the only practical answer. A 5-gallon pot could store 6000 BTUs... but that is only 1 hour of burner time. A thick blanket is best.


Fins won't help. In fact, they will reduce radiant heat by cooling the pot. And by definition, all the heat is going into the air, so convective surface does not help.


The only thing that helps is a flue, so you exhaust, primarily, only the combustion products. If you want it to be safe in a boat, a sealed unit is required... but that is another subject.

[thinwater]

Originally Posted by sailorchic34

I heard a rumor that a blonde engineer,...

Or so I heard anyway ...

That is so funny! I did something similar (based on a different heat source) for my F-24. Just a few simple calculations and a little attention to detail.


I hate the notion of an unvented heater... so add a vent!

[Juho]

Originally Posted by thinwater

Fins won't help. In fact, they will reduce radiant heat by cooling the pot.

I was thinking of the pot as a fin of the stove. In that case I considered a metal fin (and a fan) to be a more effective solution.

I maybe didn't follow all of the discussion properly since I assumed also a flue to be present (in which case catching the heat better than a clay pot could do becomes important).

[bensolomon]

Originally Posted by john61ct

link to brand or better, a purchase source please?

Source-Local liquor store. Brand-Everclear.

[hellosailor]

Everclear is sold at 120, 150, and 190 proof. The most common being the 150, AFAIK.

Dockhead, I think the electric mattress heaters are just totally unknown outside of truck stops and some RV stores. And then again, their electrical drain isn't trivial, so the heavy comforter still has a reason for being.

[Pizzazz]

Some comments:

1. Any burning carbon produces CO2. CO is produced when you burn alcohol, gas, diesel whatever and there is not enough oxygen for complete combustion to occur. If you have a crack in the window next to the burning flame you are unlikely to run out of oxygen. Anyone can test this by installing a CO detector close by and watching the buildup of CO before and after you open the window. You do not even need to exchange the air as the higher oxygen concentration outside will push oxygen inside. Check it for yourselves. Years ago, in some parts of the world, people were using gas heating appliances to heat entire homes. Hundreds of thousands of people with very few deaths. Of course some people are paranoid. I do not recommend it either not because it is unsafe but because people forget (tired, drunk, etc.) and lose their vigilance.

2. Regarding stored heat, you either need water or a huge mass, i.e. engine. You can store about 5,000 BTUs in a 6 gallon water heater and about as much in a the engine (if the engine is 450 lb, the specific heat of iron is 11% of water, approx. the same. If you need to store more heat the only practical solution is to fill the bilge with seawater warmed by the engine or to heat the water in the fresh water tanks (or the waste tank of you are comfortable with the seals - an 20 gallon waste water tank will give you 15,000 BTUs.

3. Infrared heat is great on boats as long as you are willing to keep an infrared lamp (250W) pointed at you at all times. Kind of difficult but very efficient and economical. You can also use it in the cockpit at night. Producing infrared heat from a flame is hard as mentioned above.

4. The original question was for heating a 51 ft boat. I estimate you need min 70-80,000 BTUs per night for that boat. This will not come from alcohol, even propane is going to run out quickly. You need a forced air diesel heater, a reverse cycle AC or temporary propane.

SV Pizzazz

[newhaul]

Originally Posted by hellosailor

Everclear is sold at 120, 150, and 190 proof. The most common being the 150, AFAIK.

Dockhead, I think the electric mattress heaters are just totally unknown outside of truck stops and some RV stores. And then again, their electrical drain isn't trivial, so the heavy comforter still has a reason for being.

https://www.my12voltstore.com/mobile...roductCode=T36

If its 12 volt they have it


Here's one down under
https://www.12volt.com.au

[thinwater]

Originally Posted by bensolomon

Source-Local liquor store. Brand-Everclear.

What I'd like is a link to cheap stove fuel. Vehicle ethanol is only about $2/gallon, so why is denatured ethanol $15-30/gallon?

[Jammer]

Originally Posted by bensolomon

I respectfully disagree. I specifically use 200 proof grain alcohol which has no water in it. In addition, since it is not "denatured", it does not contain methanol which is what is used to denature alcohol for a fuel use. Therefore, with no methanol, pure grain alcohol will produce zero carbon monoxide and an indetectable amount of water.

Our exhaled breath will produce more condensation then burning grain alcohol. Anything less than 100% pure alcohol, there will be water in it and condensation will be formed.

Well, it's like this. The best you can hope for is:



CH3CH2OH + 5O2 -> 2CO2 + 6H2O


The CH3CH2OH is your ethanol, you burn it with oxygen, you get some CO2 and some water. That's your basic 10th grade chemistry, right there. For every 23 grams of ethanol burned you get 19 grams of water. I'll let you look up the molecular weights and check my math, if you want.


If it doesn't burn completely, and some of it won't, you get:


CH3CH2OH + 4O2 -> 2CO + 6H2O


Now, how much CO you get, and how much CO2 you get, depends on the conditions of combustion.


But then again I am a scientist of very small mind and perhaps do not grasp these concepts as fully as you do.

[Dockhead]

Originally Posted by hellosailor

...Dockhead, I think the electric mattress heaters are just totally unknown outside of truck stops and some RV stores. And then again, their electrical drain isn't trivial, so the heavy comforter still has a reason for being.

Well, they come in 230v (110v) also, and since they only draw 50 to 80 watts or so, it's no big deal running them from even a very small inverter. There is ZERO power loss with the inverter in this case, because the inverting losses end up as heat


I can easily run 80 watts all night from my battery bank, and the duty cycle will mean average consumption will probably be much less.


But I agree with you -- the heavy down comforter is generally fine for me without any kind of heating, down to about freezing. But for someone with inadequate cabin heating, an electric mattress heater could be a great solution -- maybe even just heat the bunk for an hour before getting into it, and switch it off.


Unless it is near freezing or below, I shut off my heat at night, personally. I even like sleeping in a cold cabin, under a nice down duvet.

[Dockhead]

Originally Posted by thinwater

. . . The only thing that helps is a flue, so you exhaust, primarily, only the combustion products. If you want it to be safe in a boat, a sealed unit is required... but that is another subject.

Originally Posted by thinwater

. . . I hate the notion of an unvented heater... so add a vent!

Amen! A flue solves everything -- getting the nasty combustion products and water vapour out of the boat and away from your lungs, but keeping the heat in.


There's just no shortcut around this, if you want to heat your boat by burning something.


That wouldn't help the OP, of course, who only needs a temporary solution, but I think we found out that he has reverse cycle heat.

[Bill O]

Originally Posted by hellosailor

Everclear is sold at 120, 150, and 190 proof. The most common being the 150, AFAIK.

Dockhead, I think the electric mattress heaters are just totally unknown outside of truck stops and some RV stores. And then again, their electrical drain isn't trivial, so the heavy comforter still has a reason for being.

Everclear is the drinking variety of grain alcohol. They do make a "utility" 200 proof (100%) grade ethanol which is not for human consumption. The price was fairly steep to use for heating at >$30/gal (if you purchased 5 gal.).

Looked that the truckers 12V mattress heaters and they were much more expensive than the smaller electric blankets. The electric blanket that I was looking at only drew 3.7A (~40W) and had a timer so it would turn off if you fell asleep. The bigger blankets and mattress heaters will draw more due to their increased area.

Totally agree it should be used in conjunction w/a good comforter. Even w/supplemental heat in the cabin, when I was living aboard with thick ice surrounding the boat, I would pre-warm the bed w/an electric blanket. Admit it is a luxury item and you could tough it out until you body heat did the trick, but then again it makes a big difference in comfort.

Also think it would be good as an emergency heat source for someone suffering from hypothermia.

Bill O.

[Jack Sanford]

A word of caution on the use of a Origo Heat Pal. They put out a LOT of moisture, which then condenses on a cold exterior of the cabin. In the right conditions, it will be raining inside your boat.