Galley, Gas v Spirit comments

[Bilgediver]

i

On a small boat an Origo is the business!

If an Origo flares up and or stinks to high heaven then enough has been posted in this thread to show what to do to correct it.

Used properly there is little to no smell, no flaring or control problems, no evapouration wastage and no sooting of pans....

I got mine as a temporary measure many years ago and it performed so well it stayed.

 

[Alfie168]

Totally agree - the single ring Origo in my 1st boat was awful. It flared up when people tried to light it, ensured anyone below in any seaway was quickly sick, cost an arm and a leg to run and had great difficulty frying bacon.

I tore it out and replaced it with an high-pressure Camping Gaz.

I can only think that all those who laud the Origo, never do any serious cooking.

You'll NEVER find one on a liveaboard.

A number of points here. If its flaring up that is operator error, overfilling most likely, or incorrect fuel. No its probably not suitable for a liveaboard as they are quite basic. I've cooked a couple of decent stews on mine, so it is possible to cook properly.

What Origos offer is simplicity and safety. Gas on boats is a known risk factor with an added maintainance burden, and I take your 'costs an arm and a leg to run' comment with a pinch of salt in view of that and the installation costs of gas. I'm not anti gas, installing and repairing it is my living after all, but I am a fan of the Origo which is a perfectly adequate solution for small boats and long weekend sailing. Anything over a week and I think I'd miss an oven.

Tim

 

[dave.zap]

I have a Origo 1500, It dutifully boils water for coffee before I go to work each morning and meals in the evening.

It smells if I put the wrong type of fule in it, either way the smell does not bother me.

I think the spirit stove is way safer, I would not want to use any other.

Either way you should follow the instructions for filling, not a good idea to over fill them.

 

[Nealo]

You sure about that? All other things being equal, gas density is proportional to molecular weight.

Air is 80% N2 (m.w. 28) and 20% O2 (m.w. 32) so has an effective m.w. of 29 (ish).

Propane (C3H8) has m.w. 44 and therefore sinks, as you say. Petrol is heavier hydrocarbons and therefore even denser than propane. Ethanol (C2H5OH) has m.w. 46 and therefore just a tad denser than propane.

Methanol (CH3OH, m.w. 32) has the same gas density as oxygen and I'd therefore expect it to diffuse away pretty fast. Same with ethane (C2H6, m.w. 30). Methane (CH4, m.w. 16) is lighetr than air, which is one reason it was used - as a component of Blau Gas - as fuel in the Graf Zeppelin airship.

Well, well, I must admit I had assumed that the paranoia surrounding propane/butane was because these gases have qualities, eg a very high molecular density, which makes them more likely to settle in the bilge of a boat. eg. BSS extract - "propane sinks in air...and does not readily disperse" The BSS makes no mention whatsoever of spirit stoves, though I do remember some directive about spirit stoves being preferable to portable propane/butane stoves. I'm confused now.
My understanding is that the volatility of gases is hardly affected by the relatively weak force of gravity. To put it another way, if you mixed two different gases in a sealed container, however long you waited the heavier gas would never "sink" to the bottom, it's not like mixing liquids of different densities. Going back to petrol/alcholhol fumes, I suppose it would be correct to say they would, if undisturbed, drift towards the floor initially, but almost immediately "bounce" back up again. Propane's lower molecular density should make it even less likely to settle on the floor, I mean, it's only 1.5 times as heavy as air, the natural air movement in a boat alone would surely dissuade it from sinking to the floor, and as for the bilges filling up with a dangerous mixture of propane and air, it just doesn't seem to me to be very likely.
I'm glad Ubergeekian has pointed this out, I must admit I have never been over concerned about the dangers of petrol/alchohol fumes, thinking that they are easily wafted away. It seems I should be even less concerned about propane, unless I am missing something??

 

[2Tizwoz]

Well, well, I must admit I had assumed that the paranoia surrounding propane/butane was because these gases have qualities, eg a very high molecular density, which makes them more likely to settle in the bilge of a boat. eg. BSS extract - "propane sinks in air...and does not readily disperse" The BSS makes no mention whatsoever of spirit stoves, though I do remember some directive about spirit stoves being preferable to portable propane/butane stoves. I'm confused now......
........ It seems I should be even less concerned about propane, unless I am missing something??

What you are perhaps missing is the vapour pressure and lower explosive limits of these fuels.

Butane and propane are gases at atmospheric pressure so that when they leak they immediately form a potentially explosive mixture of considerable volume

whereas the vapout pressure of alcohol is relatively low so that an explosion is much less likely.

The densities are important as they readily sink to form an explosive accumulation, and displace air which we need to breathe, in addition to their flammability problems.

The risk of a problem working with the gases is much higher than the liquid fuels, that's why alcohol is safer.

 

[Ubergeekian]

To put it another way, if you mixed two different gases in a sealed container, however long you waited the heavier gas would never "sink" to the bottom, it's not like mixing liquids of different densities.

Sort of.

There are two different processes at work. Gravity tries to pull the heavier stuff down while diffusion tries to mix them together. Diffusion takes longer to happen, so if you start with a layer of propane under a layer of air it will take a while for the two to mix properly. Once mixed, though, they'll never separate.

So yes, you do have to worry about propane and even more about petrol fumes: they will form a layer at the bottom of the boat and before diffusions has mixed them away, that't not a good thing.

The only two gases for which gravity beats diffusion, by the way, are hydrogen and helium. There are negligible quantities of either in the atmosphere because air is so much heavier, so H and He float to the top ... where their thermal velocities are higher than escape velocity.

 

[Nealo]

What you are perhaps missing is the vapour pressure and lower explosive limits of these fuels.

Butane and propane are gases at atmospheric pressure so that when they leak they immediately form a potentially explosive mixture of considerable volume

whereas the vapout pressure of alcohol is relatively low so that an explosion is much less likely.

The densities are important as they readily sink to form an explosive accumulation, and displace air which we need to breathe, in addition to their flammability problems.

The risk of a problem working with the gases is much higher than the liquid fuels, that's why alcohol is safer.

So a petrol/alcohol leak could "only" cause a fire, wheras a propane/butane leak could cause an explosion..? Presumably that is why there is greater concern about bottled gas.

 

[NUTMEG]

Great, this forum

Bit like the perennial Seagull debate. I have a mate that says they are only good for anchors, whereas I loved mine (before they were nicked) never let me down, always started etc. I did make a point of regular servicing though. Have had Origos on both boats I have owned, the latest being the twin burner version. Always used meths, never 'flared', boils kettle, cooks bacon and eggs and never worried about the odd whiff. In fact I quite like it. Different strokes for different folks?

 

[Seajet]

Though I am in the pro-gas camp, I'd certainly say you need to be careful with it.

I simply cannot imagine having problems with an actual gas bottle, it's the installation which gets people.

For a start, discipline must be rigid with everyone on board that every time the cooker is turned off, the regulator on the bottle should be turned off, only turned back on immediately before use.

Gas bottles must be stored in a ventilated locker, with drains at the bottom of the locker to either overboard or into the cockpit, if it's self draining.

It's worth mentioning that a lot of older boats do not meet this requirement, so to my mind are uninsured, though that's the least of one's worries.

My Anderson 22 originally had the gas bottles stowed in a non-draining locker, while the standard fit was a bottle directly beneath the cooker, which is itself illegal now.

I got round it by making an extended bridge-deck, ventilated at the sides and lower edge, which also stows handy buckets etc and makes a good seat; the regulator can be reached from inside the cabin.

It's not only small boats which one has to check; a few years ago a services Nicholson 55 exploded at Poole town quay, a crew member lost a leg and the boat was utterly destroyed by the explosion, not fire; surprising such a boat in pro' hands should have a fault like that, but she suffered from lots of passing crew who weren't sufficiently familiar with the set-up, it seems the regulator had been mis-attached.

I saw a power cruiser go up in spectacular fashion; the gas cooker had caught light somewhere it shouldn't, at the attachment I presume, and the crew wisely jumped overboard before the bottle went; it was their first trip, again a snag with installation and user. The boat was uninsured.

The flexible hoses at each end of the installation, ie at the regulator one end and for stove gimballing at the other, should be replaced every winter; the date is stamped on this hose, and this is in my view the worst potential point for leaks.

The armoured type of flexible hose must be avoided ( I think it's illegal now ) as one cannot see the state of the rubber underneath.

I learned that one the hard way; had just bought a Carter 30 which had this stuff, was having a lumpy late season sail from Salcombe to Fowey, went below to check the chart while off the Eddystone light.

I put the kettle on then turned to the chart, when I next looked around there was a moderately fierce jet of flame going vertically up from the back of the cooker.

I can assure you " Fire ! " was the second word I shouted...my chum in the cockpit turned it off at the bottle, while I already had a dry powder extinguisher going.

It was over in seconds, what I didn't know is that this dry powder is quite corrosive, and it pitted some of the woodwork; the fire had not actually done any damage.

If it had got hold we would have been poorly placed, about 10 miles offshore in a F6 with a stowed inflatable and no liferaft.

As long as the gas pipe run is well done ( mine is one length, no joins which is how I like it ) and the flexible ends are maintained, it's a good way to cook food, I have 2 burners and a grill on my Anderson 22.

I would really like an oven for cruising, but it's simply not possible to fit one; I aim to try out the latest hob-top pans, though earlier ones made claims they could not keep to, and of course if one can get enough heat out of it an Origo would work one of these too.

Despite the snags outlined above I still prefer gas, though if crewing / chartering a gas equipped boat I wasn't familiar with I'd run a discreet eye over the installation, which would be wise for anyone to do whether their own boat has an Origo or whatever.

 

[andygc]

Gas bottles must be stored in a ventilated locker, with drains at the bottom of the locker to either overboard or into the cockpit, if it's self draining.

It's not only small boats which one has to check; a few years ago a services Nicholson 55 exploded at Poole town quay, a crew member lost a leg and the boat was utterly destroyed by the explosion, not fire; surprising such a boat in pro' hands should have a fault like that, but she suffered from lots of passing crew who weren't sufficiently familiar with the set-up, it seems the regulator had been mis-attached.

Well worth reading the MAIB report on Lord Trenchard's explosion. The point is not that the regulator leaked, but that the gas locker was not gas-tight. That resulted in gas passing through into the hold space where the generator was installed, rather than venting safely down the locker drain and overboard. The accident was not a consequence of crews being unfamiliar with the boat, it was a consequence of management failures arising from divided responsibility. As the MAIB report said, the cylinder connection was the only one accessed by crews and consequently was an area of a high risk of leakage. The system should have failed safe, but didn't because the gas locker was not properly sealed.

The same relatively high risk exists on any boat with gas, however familiar the users are with changing gas bottles - connector seals can leak small amounts of gas without being noticed. If your boat has a properly sealed gas locker then you can fail safe. If the locker is not gas tight (apart from the drain) it may fail unsafe.