Wednesday, January 31, 2018

________________________ CHANGING STOVES ________________________

This (above) is my yacht 'Mariner's stove. It is a primus stove that uses kerosene under pressure (Stored in the tube on the bottom of the stove). The kero burners are pre-heated at their bases with meths which has the effect of vapourizing the kerosene which then burns with a clear blue flame. When they are in good working condition they are great little stoves and I love them. When they get old and worn they develop a number of alias's - 'Flame Thrower', 'Grenade' and 'Bomb' come to mind. New Kero burners for primus stoves are now available again but they are very expensive and have to be specifically imported into NZ.

So reluctantly I modified the old primus by lowering the burner tray and purchasing a couple of gas camping stoves which fitted neatly into the recessed trays. I don't much like gas on a boat but I thought this might be a compromise as I would only be using small canisters rather than having a professionally fitted installation complete with a large gas bottle.

Right from the start I had a bad feeling about what I was contemplating. Instead of listening to my gut instincts I simply forged ahead. I sobered up when I read the instruction leaflet that came with the camping gas stoves, which gave this advice:

- "This appliance uses oxygen when in use. DO NOT light or use indoors, in a tent, vehicle or other enclosed areas. A fire or carbon monoxide poisoning could cause injury or death" - Yikes!

- " DO NOT obstuct the flow of combustion and ventilation air. - OMG !

- " DO NOT use any windscreen (ing) with the stove. Any windscreen, including a standard windscreen, may cause the canister to explode. - Fucking hell !

- " DO NOT use the stove.......... in close proximity to another stove, or near any heat, fuel or ignition source." - Shite! You mean I have two bombs side by side!


- Sounds as though if I was to take the gas option I would have a stove ensconced in my boats galley with the explosive power of an Exocet Missile! Yikes! and Yikes!! again!

Only a fool would not take this advice. So I used that old adage that changing my mind is a males prerogative and went in another direction.

So shipmates, I did the research I should have done right at the beginning of this little sojourn and decided to change fuel.

I have purchased a new stove with a couple of nifty adjustable pot holders. It's a Swedish built Dometic 3000 two burner stove specifically designed for use in tents, campers and boats. It burns meths which is not pressurized in any way which is a big safety factor. It eliminates the pressurized flare ups that can occur with a primus. Any meths fires can be put out with water.

According to the Utube videos I have viewed and literature I have read a meths burning stove is the safest option available and has the advantage that meths can be extinguished using water in the unlikely event of a fire. The only disadvantage that I can see is that meths doesn't burn at the same fierce temperatures as gas or kerosene, so the kettle will take a little longer to come to the boil..... but shipmates if you are a sailor traveling everywhere at 6 - 7 knots or less, what's the bloody hurry?

The big advantage is that the stove is relatively safe, simple, easy to use and fits neatly into the modified gimballed frame of the old primus stove. It is also a compact, non intrusive and reasonably attractive looking little unit.

So I am happy to have this job ticked off the list. One down, three more jobs to go and then we can go sailing again.


Paul Mullings said...

Surely any open flame burns oxygen?

Steve-the-Wargamer said...

Happy New year, Alden.. not sure I've wished you it yet.. how is Mariner - was hoping to see have seen some trip reports by now... better hurry, the first signs of spring are showing here in the UK, so the new season is just around the corner, which means the same for your end of season.. :o)) On Sparrow I went the gas canister route as per your interim solution but different canister type... ==>$Web$&$DefaultPDP570$

Alden Smith said...

Happy new year to you Paul. You are quite correct, any open flame burns oxygen and dangerously produces carbon monoxide.

"Carbon monoxide is produced by the incomplete combustion of carbon-containing fuels, such as gas (domestic or bottled), coal, oil, coke and wood. Gas stoves, fires, heating boilers, gas-powered water heaters, paraffin heaters, and solid fuel-powered water heaters are all potential sources of carbon monoxide."

So the important point regarding using stoves and fires in confined spaces is to make sure that the space is well ventilated. On 'Mariner' I am usually at anchor, head to wind with the forward hatch open and a good flow of air flowing through the boat when the stove is in use.

My main worry in all of this is the confined space where the stove is situated. A test on my boat with the camping gas stoves proved a real risk of explosion as the area around the stove heated up in an alarming way. The gimballed stainless steel frame became extremely hot and would have scorched the surrounding woodwork if I had continued. The new meths stove doesn't burn so ferociously and isn't under pressure so the risks are significantly lower.

Dan Gurney said...

Take care with that stove! Sounds like you are. Gotta breathe good air, above all. Warm food and drink are definitely secondary.

What’s up with the barnacles, I wonder? Are waters in the harbor warmer?

Alden Smith said...

The barnacles are a real big problem. A few decades ago I would pull the boat out after a year and there might be say half a dozen or less. Now after 4 months 'Mariner' is thickly covered with them and they have to be scraped off.

Whangarei city is at the head of a river where my boat is moored is over 20 nautical miles from the coast. Boats moored in the river and in the wider harbour are being adversely affected.
Boats moored in coastal bays are not having the same problem with barnacles, so it seems something particular to our harbour. I thought it might be a rise in sea temperature but as someone pointed out to me the other day, he had lived well up on the Australian coast at Cairns where the water temperature gets up above 30 degrees without producing the fouling problems we have here.

I think the reasons are complex - fertilizer runoff from the huge numbers of surrounding farms providing nutriments for barnacles combined with rising water temperatures may be part of the reason.

It's getting to be such a problem that I may have to seriously consider somewhere else to moor my boat, maybe out on the coast at Tutukaka or up North in the Bay of Islands.

Steve-the-Wargamer said... if I understand you're mooring you're mostly fresh/river water? If you sailed though you would travel through brackish/salt as you got towards the coast... if I remember rightly that should kill them? Also is Coppercoat allowed in NZ, I know some countries have more stringent rules on biocides and the like than others..

Alden Smith said...

Steve, the river is very tidal, but it's source at the head of the river is fresh water - similar I guess to the Thames River which well inland would be fresh water but becomes a tidal mixture at London and further out into the Thames estuary.

You may be correct about the greater concentrations of salt killing the barnacles as two friends have boats out on the coast and they are not getting the infestations that those of us inland are plagued with.

Coppercoat is available in NZ and is advertised as being more environmentally safe than other biocides. I know that it is expensive but how much I don't know at this stage. Because it is an epoxy product it would require removing all the existing antifouling paint - so it would be a bit of work, but I am seriously considering coppercoat as a solution along with maybe mooring somewhere else.

It would be useful to hear of others experience with Coppercoat rather than just reading the vested interest advertising - I will do some internet research!

Thanks for your comment Steve, I thought about Coppercoat (and copper sheathing which really isn't appropriate for my type of yacht) the other day - so your comment has prompted my thinking again.

Alden Smith said...

...... and perhaps on a lighter note, when 'Mariner' was hauled out and I was dealing to the diesel engine and the barnacles the owner of a steel boat in the boat yard smeared one third of one side of his yacht with lard! He had heard that this kept the barnacles away and the hull clean - we are all waiting with baited breathe for when he hauls out again so we can see how the experiment fared!!

If it works be prepared for lard to rocket in price like everything else connected with the marine industry!!

Steve-the-Wargamer said...

Ha... I've heard the same about udder cream which is a thing used in the dairy trade apparently... Sir Robin K-J swears by a bloody big handful of the hottest chilli power mixed into the final coat of antifoul... no idea if any of these things actually work... :o))

Alden Smith said...

Yes, urban myths, snake oil, old wives tales and a lack of common sense have always been at large in the world - but if buckets of hot chilli powder could be scientifically proved to do the trick I would try it!!

Alden Smith said...

Happy New Year to you Steve. No one is more sorry about the lack of trip reports than I am; but what with a couple of months in the UK awaiting the birth of a grandchild and the usual dislocation of working time over Christmas I haven't as yet got 'Mariner' fully sorted. The jobs requiring completion are: 1. Sorting the Stove, 2. restoration of a whale gusher bilge pump (the aluminum casing is heavily corroded and a new plastic one is over $300) and 3. Fix a leak in 'Mariners' fuel tank.

Also the boats in Whangarei Harbour are fouling up with barnacles at an alarming rate (a real problem and no one really knows why) so before any trips I will have to come out, scrap, scrub and paint before any sailing happens.

Luckily though, here in the north of New Zealand we are able to sail for 12 months of the year, so I will get some sailing in hopefully in the near future when all the jobs are sorted and I have been and raced in the Zephyr Sailing Dinghy Nationals.

Ben said...

Saw your blog relative late so I didn’t have to make the smartass remark that all flames need oxygen to burn. 😊. You are right, methanol produces a relative cool flame, because during burning a lot of water vapour is produced, compared to gasoline for example.
The big disadvantage that methanol shares with propane / butane gas and gasoline is that the vapour is heavier than air. In case of a leak it collects in the lower part of the space it is in. Here it accumulates till the concentration of the methanol reaches the lower explosion limit (LEL = 6,7 %) and a small spark or flame with a temperature higher than 470 oC will start an explosion. Fortunately this LEL is more than 3 times higher compared to propane/ butane gas or gasoline.
A disadvantage in high temperature countries is that methanol has a low boiling point of 64,7 oC. Above this temperature no liquid can exist. Furthermore spilled methanol that burns produces a colourless flame that is hard to detect.
So it is a balance of pro’s and con’s
Do you have a cardanic construction to hold the stove to compensate for the ship’s movement?
Good luck with the Zephyr Nationals in two weeks

Alden Smith said...

Ben, boat stoves are a metaphor for life in general i.e everything is a compromise.
I hope I have made a good choice, time I guess will tell on that score.

One of the advantages of my kind of sailing routine is that there is usually a good dose of sailing before the stove is used, which means a good deal of air has circulated through the boat dispatching any fumes that may have accumulated. Having said that I don't know of any gas explosions that have occurred with a meths burning stove.

The rules I guess when using naked flames in any context is to be very careful, vigilant and keep all of the cooking kit clean and well maintained.

I am not sure what a "cardanic construction" is that you are referring to but the new stove will be gimballed within the modified old kerosene stoves gimballed frame.

Thanks for the best wishes for the Zephyr Nationals; I am looking forward very much to the weeks sailing - my goal is to finish every race and get a placing in the top half of the fleet - if that doesn't happen I will just have to go back again next year and try again!!

Ben said...

With a cardanic construction I mean a pivoting balance holding the stove, that keeps the stove horizontal by gravity when the ship is not.

Alden Smith said...

Yes, I looked it up on Google Search ---- Cardanic from CARDAN, meaning "a universal joint that transmits motion unchanged."

In Kiwi parlance this mechanism has always been referred to as a 'Gimbal' in reference to marine stoves and compasses. With the gimballing of compasses the gimbal allows the compass to keep level fore and aft as well as from side to side. With most marine stoves that I have seen the gimballing is usually only from side to side - keeping the top of the stove level when the yacht heels; which I guess is a kind of 'half gimbal'.