Hey JimB,

Thanks for the info!

I'm embarrassed to reveal my ignorance here, but why is the ratio of CO2
to H2O relevant, rather than just the H2O? I've encountered other
combustion analyses that also focused on that ratio.

Appreciate your input.

Chuck


News f2s wrote:
"chuck" wrote in message
ink.net...

A molecule of alcohol does not contain a molecule of water.

As has already been pointed out in this thread and elsewhere,
and which I pray is not in dispute, is that ALL hydrocarbon
combustion yields water vapor as a product.

The question has been whether to expect a greater (and to
capture the essence of the thread, unacceptable) amount of water
vapor from a btu generated by burning alcohol, than from a btu
generated by burning, say, propane. Even better, we would like
to know how much more water vapor is generated from alcohol
combustion if in fact there is more. Because different alcohols
can be used (methanol, ethanol, isopropyl, etc.) combustion
chemistry is likely to be difficult to generalize.

Unless someone can provide the detailed chemical analyses, we
cruisers are stuck with testing and observation. Someone
suggests a hypothesis that burning alcohol will make my cabin
clammy. I conduct a thousand experiments, the results of which
contradict the hypothesis. Therefore, I have demonstrated that I
believe gravity is just hype! Now there's a brand of science
only Fox could sell.


If you ignore the heat output from each reaction, and just look at
the ratio of carbon dioxide molecules to water molecules produced,
there's no doubt that burning an alcohol produces more water.

Methyl alcohol, 2*CH3-OH + 3*O2 = 2*CO2 + 4*H2O
Ethyl alcohol, 2*C2H5-OH + 9*O2 = 4*CO2 + 12*H2O

Propane, C3H8 + 10*O2 = 3CO2 + 5*H2O

Benzene, 2C6H6 + 15*O2 = 12*CO2 + 6*H2O

On the heat equation, since alcohol is already partly oxidised,
you're likely to burn more of it to reach the same heat result.
That means yet more water.

Whether this matters is a subjective judgement . . . it obviously
offends some, and not others. Fine.

JimB

On Sun, 26 Feb 2006 09:00:27 -0500, DSK wrote:

Is your refrigeration AC or PTO from the genset? We
considered the 120VAC option but went with 12V DC instead...
takes a lot longer to pull down but less dependent on
outside power & works longer "off the grid" IMHO. But then
we invested heavily in insulation, too.

It is the 120VAC Grunert system that was original equipment on the
Grand Banks although I have upgraded it with a digital thermostat. It
requires about 2 or 3 hours a day of generator time. We also have a
holding plate freezer capable of keeping ice cream at the requisite
zero degrees. Talk about nautical decadence... Both systems work
well, however the freezer unit has been totally rebuilt with new
plates and condenser in the last year.

"chuck" wrote in message
nk.net...
Hey JimB,

Thanks for the info!

I'm embarrassed to reveal my ignorance here, but why is the
ratio of CO2 to H2O relevant, rather than just the H2O? I've
encountered other combustion analyses that also focused on that
ratio.

For a given heat, you're breaking down a fuel (takes some energy)
then oxidising its components (gives energy back). One element of
this thread was breaking into the criticism of alcohol fuels 'that
produced more condensation'.

For a given heat, alcohol fuels do produce much more water than
carbon rich fuels. The easiest way to see this is by looking at
the ratio of combustion products, and that's easy to envisage if
you look at the reaction equations.

At the top end you could consider a charcoal heater - all carbon
dioxide, no water. We'll dodge the issue that pure carbon burning
easily creates carbon monoxide if it is not extrememely well
ventilated. Which is always the case with all carbon rich fuels if
they're not adequately ventilated. Something that hasn't been
touched in this thread so far . . .

JimB

"News f2s" wrote in news:dtsb4h$mrb$3
@news.freedom2surf.net:

Methyl alcohol, 2*CH3-OH + 3*O2 = 2*CO2 + 4*H2O
Ethyl alcohol, 2*C2H5-OH + 9*O2 = 4*CO2 + 12*H2O

Propane, C3H8 + 10*O2 = 3CO2 + 5*H2O

Benzene, 2C6H6 + 15*O2 = 12*CO2 + 6*H2O

On the heat equation, since alcohol is already partly oxidised,
you're likely to burn more of it to reach the same heat result.
That means yet more water.

Whether this matters is a subjective judgement . . . it obviously
offends some, and not others. Fine.



I believe a more correct term than "offends" would be "baffles".

I get light headed, myself, when anyone talks about alcohol. It's probably
just a Pavlovian response, though...(c;

"Larry" wrote in message
...
"News f2s" wrote in news:dtsb4h$mrb$3
@news.freedom2surf.net:

Methyl alcohol, 2*CH3-OH + 3*O2 = 2*CO2 + 4*H2O
Ethyl alcohol, 2*C2H5-OH + 9*O2 = 4*CO2 + 12*H2O

Propane, C3H8 + 10*O2 = 3CO2 + 5*H2O

Benzene, 2C6H6 + 15*O2 = 12*CO2 + 6*H2O

On the heat equation, since alcohol is already partly oxidised,
you're likely to burn more of it to reach the same heat result.
That means yet more water.

Whether this matters is a subjective judgement . . . it obviously
offends some, and not others. Fine.



I believe a more correct term than "offends" would be "baffles".

I get light headed, myself, when anyone talks about alcohol. It's
probably
just a Pavlovian response, though...(c;

So, I was right.. alcohol is lighter than air. :-)

--
"j" ganz @@
www.sailnow.com

In article . net,
says...


A molecule of alcohol does not contain a molecule of water.

A molecule of ethyl alcohol has two carbon atoms, six hydrogen atoms and one
oxygen atom. That oxygen atom is linked to one hydrogen and one carbon. When
it breaks the bond with the carbon it links to another hydrogen making H2O
from elements that are part of the alcohol molecule. So it does not contain a
molecule of water per se, just the components.

Just putting my 2 cents worth in. I have owned and operated a Sea Swing pressurized
stove over 30 years and never had any incidents with it. It is basically
an Optimus #4. It has been used heavily, when I took long cruises living on the
boat
for months at a time, and it was a single burner and only cooking stove aboard.
The only problem I have with alcohol is finding the right brand to burn under
pressure. I have found that brands like Parks burn well, whereas other brands are
real duds. I suggest trying small samples first if one is not sure.

Sherwin D.

Mys Terry wrote:

On Fri, 24 Feb 2006 21:24:26 GMT, chuck wrote:

Roger, the non-pressurized alcohol stoves have to be the safest of the
liquid fuel types in terms of the fuel itself.


Two problems with alcohol stoves, even if not pressurized:

1) major by-product of burning alcohol is water, and lots of it. It's a great
way to make your cabin clammy in a hurry

2) The real problem with all alcohol stoves from a safety standpoint is that the
flame is almost completely invisible. If somebody doesn't see that as a
significant safety issue, they just aren't thinking clearly.

On Fri, 24 Feb 2006 19:38:47 GMT, Mys Terry
wrote:

On Fri, 24 Feb 2006 11:07:01 -0800, "Capt. JG"
wrote:

I don't think you'll find it in the bilge... it's lighter than air unlike
propane.

???

alcohol is lighter than air?

Thanks. I didn't know that!

In that case, I'll have another.

(*******s were out of Gosling's)

R.

On Fri, 24 Feb 2006 14:18:40 -0500, Wayne.B
wrote:

On Fri, 24 Feb 2006 18:18:55 GMT, "Roger Long"
wrote:

If that bottle of stove alcohol in your cockpit locker leaks and
drains into the bilge, how much danger is there of explosion or fire?

Alcohol mixes readily with water and that will quickly reduce its
flammability below the danger level in most cases. The real risk with
alcohol on boats (other than consumption), is with the old fashioned
pressurized stoves. They have probably caused more boat fires and
burn injuries than any other single reason. Another problem with
alcohol is filling a stove that is already hot, typically because it
has run out while in the middle of cooking dinner. It is very easy
for the vapors to ignite in that situation and the flames are
difficult to see in sunlight.

I had two bad flare-ups with alcohol and finally converted the
Homestrand to propane. I haven't finished the installation (the rules
just changed here recently and apparently all that copper tubing in
the forepeak is no longer applicable) and use a Coleman camp stove in
the cockpit. That and the barbeque suffice, but I already use the
gasoline/propane sniffer in the bilge and it works well. I have all
the pieces except the new "to spec" tubing...I just have a few more
pressing jobs this spring...like new portlights.

R.

Rodger,
Fire is the biggest risk in boating, very few events can be more
catastrophic than a fire on board a boat. All heat sources represent some
risk, but volatile hydrocarbons represent the greatest risks. I will not
carry gasoline, LP gas, CNG or alcohol. I carry only diesel and everything
on the boat is electric. I think diesel electric represents the lowest risk.
You may choose differently. Diesel electric solutions are not only the
safest, but they also offer low weight, simplicity, ease of use and the
smallest consumption of space.
Steve

"Roger Long" wrote in message
...
I can't recall seeing anything definitive on this topic.

If that bottle of stove alcohol in your cockpit locker leaks and drains
into the bilge, how much danger is there of explosion or fire?

--

Roger Long