tophatyachts.com

Hi all,
I have only recently been enlightened that a time honoured practice with many yachties of using an upturned (empty) ceramic pot on the cooker to heat the cabin will produce toxic gas and can be deadly. Apparantly it is odourless, colourless, etc and unnoticeable, until it's too late, even with ventilation.

Yes, this is one of the dangers of smoking Pot...

Its not the POT



It's the gases [includes Carbon Monoxide, have to pay a tax on that I suppose]

being produced by the fuel being burnt in the stove!

Incomplete combustion to blame in either case I suspect.

Their is a good article in afloat this month on this subject, a couple of professors state that ceramic pots as heaters are harmless as they give of carbon dioxide!!! not carbon Monoxide, cheers Oberon.

p.s i have been heating my boats with clay pots for 35 years and never had a problem.

So whats the verdict?

My preliminary research indicates that unglazed ceramic pots are probably fine on metho stoves, whereas not so good on LPG stoves due to the nature of LPG containing a small percentage of carbon monoxide.

There is no doubt that incomplete combustion will produce carbon monoxide, and complete combustion will give you CO2. However, if you have good ventilation, you might get away with it. On the other hand, that is a relative term, and who knows what the limit is.

For my money, I go for the radiant heat option, http://www.investigator563.com/forum/vi ... ?f=4&t=362, but you still have the CO2 problem. Plus the relatively large volume of the Top Hat makes it difficult to heat.

Looks like the solution is either spend thousands on a fancy diesel heater with a flue, or just warm the hot water bottle, and dive into a warm bunk, hopefully with a warm companion.

Here is the limit for CO
What effect might carbon monoxide have on my health?

Carbon monoxide quickly enters the blood when inhaled into the lungs. Levels normally present in the atmosphere are unlikely to cause ill effects. Carbon monoxide concentration may reach harmful levels in poorly ventilated rooms during operation of unflued gas heaters or defective non-electric heating appliances, or in the passenger compartment of vehicles with defective exhaust systems. At low levels it may cause poor concentration, memory and vision problems, and loss of muscle coordination. At higher levels (200 ppm for 2–3 hours), it may cause headaches, fatigue and nausea. At very high levels (400 ppm) the symptoms intensify and will be life-threatening after three hours. Exposure to levels of 1200 ppm or greater are immediately dangerous to life. Carbon monoxide combines with haemoglobin to form carboxyhaemoglobin, reducing the oxygen-carrying ability of the blood. Long-term (chronic) exposure to low levels of carbon monoxide may produce heart disease and damage the nervous system. Exposure of pregnant women to carbon monoxide may cause low birthweight, increased foetal mortality and nervous system damage to the offspring. Carbon monoxide is classified by the NOHSC as a Category 1 reproductive toxicant (substance known to cause developmental toxicity to humans).
End quote,
200ppm is 0.02per cent. CO has 210 times the affinity for Haemoglobin than oxygen. It suffocates you witout you even knowing it and leaves a very nice normal looking corpse without the usual blue lips.
The rest of it is here;
http://www.environment.gov.au/atmospher ... oxide.html

No different to any other naked flame heating system. It removes breathable oxygen from the atmosphere in the cabin. Same reason you can't safely, or legally operate an in-flued gas heater in a bedroom.

Greg, I like your technical description though..... Ya mad scientist!

Neither carbon monoxide (CO) nor carbon dioxide (CO2) support life. Oxygen does. In an enclosed space with a naked flame, oxygen is being consumed. If there is no air movement or insufficient movement in and out of the enclosed space, even the flame will eventually go out. Carbon monoxide is less likely to be formed than carbon dioxide as it is from more incomplete combustion. It is also more dangerous as it can surpress the body's reflex to breathe. Therefore, any naked flame inside ya boat carries risk. Mostly the risk is low since there is usually enough air movement in and out of hatches etc or the flame is not long lasting such as with making a cup of tea.

The fact that folk such as Oberon11 has been heating his boat with a flame and pot for 35 years and still going strong indicates that it is not always lethal. However, it is certainly worthwhile being careful.

The danger can be unrecognised. When the Yasi cyclone hit up north Qld some years back, rain was belting down, high winds meant ya had to stay indoors, and power lines came down. One fella started his generator in his garage. Couldn't run it outside, obviously. Not so obvious was the CO build up. Sadly it killed him.

For me, I used to use an electric heater but it had a problem. It would stop working every now and then. Usually when I was ten metres out from the marina pontoon going for a sail. I think my extension cord needed to be longer. : )