Mini Bull Designs Sketti Stove REVIEW

Powerful, dead easy to light, sturdy alcohol stove - just be careful lifting a pot off before it burns out.

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by Roger Caffin | 2006-06-14 03:00:00-06

MiniBull Designs Sketti Alcohol Stove REVIEW - 1

Introduction

Mini Bull Designs claims that the Sketti alcohol stove is powerful enough for two people, is robust and simple, and doesn't require a pot stand. This review investigates these claims.

What's Good

  • Large alcohol capacity
  • Powerful
  • Stable on the ground
  • Strong - handles a heavy pot
  • Easy to use

What's Not So Good

  • Uncertainty about amount of fuel to use
  • Flaring when pot removed

Specifications

  Manufacturer

Mini Bull Designs

  Year/Model

2006 Sketti

  Construction Material

Several bits of a 25 oz Fosters beer drink can

  Construction Process

Hot-rolled seams with no tape or glue to melt

  Mechanical Design

'Pepsi-can' inner wall creates annular chamber for alcohol

  Jets

31, drilled around outside, 3/4 in (20 mm) down from rim

  Alcohol Capacity

Open centre well claimed to hold up to 4 oz denatured alcohol

  Stove Style

Looks like an open jet, but closer to pressurised in use

  Burn Time

Claimed to run for 20 minutes when filled

  Target Use

Two or more people, heavy pots and heavy use

  Weight

0.77 oz (22 g) measured

  MSRP

US $12

Performance

I have used many white gas, kerosene, and gas canister stoves. I have used some old alcohol stoves, but only a couple of the newer ultra-lightweight alcohol stoves. It had struck me that the new alcohol stoves were all slow and fragile, but Tinny of Mini Bull Designs assured me otherwise, and recommended the Sketti stove as an example.

Well, I can vouch for the strong bit. The design is such that the pot sits on top of the stove; no pot supports are needed. I tried putting some very heavy pots on the Sketti, and it simply wasn't bothered. The large Fosters can makes the Sketti more stable under these loads, compared with other smaller diameter stoves.

MiniBull Designs Sketti Alcohol Stove REVIEW - 2
Details of the Sketti stove, showing the holes around the edge

I set the Sketti up on my test bench, poured 1 fluid ounce of denatured alcohol into it and struck a flame over it with a butane lighter. Nothing happened. This surprised me, especially as I was in the middle of the Australian summer at the time. Maybe the vapour was sitting in the middle of the can and not coming up high enough for the flame from my lighter to reach it? So I dipped a timber splint into the alcohol, lit it, and slowly lowered it into the middle of the can. Indeed, the alcohol lit only when the flame was about 1/2 inch (15 mm) below the rim. With the alcohol near boiling I could light the stove with a butane lighter, but not otherwise. In cold weather or with a little breeze blowing I found I had to put the flame slightly closer to the surface of the alcohol to get it to light.

Once lit, a flame rises from the middle and dances around, but nothing comes out of the jets immediately. One could hold a pot over this flame and start heating water already: this does slightly improve the fuel efficiency, but it's hard to say by how much. About 60-70 seconds later there are flames coming out of the jets and I can lower my pot onto the rim of the can. If I do this too early, the flames from the jets go out: I have to wait until they are over 1 inch (25 mm) long for the stove to work. But once it is going, things get interesting.

While the stove is just sitting there with a big flame coming up from the middle, the jets give out small flames. It functions like an open jet stove. But when I put the pot on the rim, the centre chamber is at least partially sealed, and the stove becomes pressurised. The flames coming out the side grow larger. After a while, they grow to at least 2 inches (50 mm) long and sometimes come up the side of the pot some way. Of course, flames coming up the side represent a loss of efficiency, so small diameter pots are not recommended with this stove.

Lifting the pot off the stove while it is burning normally releases the pressure inside the stove, so the flames from the jets decrease in length. However the alcohol is still boiling with lots of alcohol vapour coming off, and the centre flame will rise, up to 2 feet (600 mm) high or more. This is a bit scary and I would not want this inside my tent. I also found that lifting the pot off the stove under these conditions has to be done with some care, or with some pot grips, to avoid getting one's arm singed - those flames can leap around a bit. If you need to remove your dinner from the flames before the alcohol has run out, much care is needed as to where and how you do it.

MiniBull Designs Sketti Alcohol Stove REVIEW - 3
Boiling up for morning tea using the Mini Bull Designs Sketti alcohol stove on the bank of a small creek.

For the alcohol to give off enough vapour to make these long flames, it must be boiling away quite vigorously. This means the flames must be providing lots of thermal feedback to the stove, and I think this is a prime requirement for a good reliable alcohol stove. Well, the Sketti sure meets this requirement. Were the jets much closer to the top of the can this feedback would be reduced - and it might not be possible to use the can as a stove support either. That said, maybe moving the level of the holes just a millimetre or two closer to the top might throttle the stove back just a little, and the shorter flames might improve the efficiency. As it is, some heat is visibly lost up the sides of narrower pots with this stove. This is a stove for big pots.

I was a bit concerned to note that the flames come out of the stove very close to the ground. I would not be game to run this stove on any surface that was burnable, let alone on the floor of the Australian eucalypt forest in summer. The risk of starting a fire seems very real. I have compromised in the bush by only using the Sketti on bare sand beside creeks, bare rock and very clean earth.

With many of my other stoves I use a small square of plywood as a stove base, to provide stability. I tried using the same base for the Sketti, but the plywood started to get a bit hot. This is the same problem as above. So in the photo above I had planted the stove into bare sand; later on I used a small square of stiff aluminium sheet as a base in the field.

The testing of these two base materials (plywood and aluminium) made me realise that the aluminium base would suck some heat out of the stove, cooling the alcohol down. Then I realised that damp sand would do the same, only worse. Fortunately, the sand in the photo was fairly dry and did not cool the stove down much. Regardless, the stove burned well.

Measurements

I have used this stove inside at home for testing and out in the (Australian) bush for real, mainly to boil water for morning tea/coffee. I have to confess that in two cases in the field I slightly underestimated the amount of fuel needed, so that the flame went out shortly before the water boiled. I was intrigued to note that the flame did go out quite quickly when the fuel ran out: from full-bore to out in a couple of seconds. The stove cooled down fairly quickly when this happened.

I had to refill the stove each time. I wasn't sure just what was safe and what wasn't, so I waited a moment in each case and then poured a bit of alcohol into the centre. The can was still slightly warm when I did so, but the addition of cold alcohol quickly cooled it down. The warmth of the empty stove has not presented me with any hazard when refilling - in my experience. Relighting is done with a twig as before.

My standard test case is to boil two full cups (500 ml) of water for tea and coffee for my wife and me in our Trangia kettle with a base diameter of 150 millimeter (5.9 inches) and the lid on. The normal boil time starting from about 20 C (68 F) was 5.5 - 5.7 minutes. This compares very well with the 10+ minutes for one cup of water I have experienced with two other small alcohol stoves I have recently tested. It includes holding the kettle over the flames while the alcohol is heating up - before the jets start working.

What I can't answer with precise numbers is whether the fuel economy of the Sketti is better or worse than for the slower, smaller stoves. It is very hard to do this comparison. The smaller (one-man) stoves are designed for smaller pots and smaller quantities of water, while the Sketti stove is a two-man stove and is designed for larger pots and larger amounts of water. Using a small pot on the Sketti is not very efficient as the flames reach up the side of a small pot far more than with the smaller stoves, and this wastes heat. As it is, the flames often lick up the side of the Trangia kettle.

Starting with exactly 1 fluid ounce (28.4 ml) of alcohol fuel in the Sketti had the kettle boiling at about 5.6 minutes, and the flames went out at 7.0 minutes. In practice I can use a bit less than the 1 fluid ounce to make tea and coffee: about 0.9 fluid ounce (25 ml) usually suffices.

The claimed burn time of 20 minutes would be about right if you came close to filling the Sketti with alcohol - this would be about 3 fluid ounces. However, you would want to be sure you need this much heat before doing so: removing the pot before the flames have gone out is risky, and there seems to be no simple way of putting the stove out. I tried blowing, but this didn't always work. A snug cap of alfoil worked if I was very quick, but I don't normally carry such a thing. Also, there is a high risk of getting burnt doing this.

MiniBull Designs Sketti Alcohol Stove REVIEW - 4
Brown goo in the bottom of the stove after some use

Other Matters

After a while I found the inside of the can looked a bit brown and wrinkly: something had been 'cooked' there. Whether this is from whatever is put in the alcohol to 'denature' it, or whether it represents varnish off the inside of the can, I cannot say. But it didn't seem to matter.

I also looked to see if any alcohol would leak from the join that runs around the base. This seemed like a strange place to put a join: up near the top might have been more logical. However, the process Tinny uses to join the parts together (hot rolling) seems to create a pretty much leak-proof seam. The rolled seam means that there is no worry about epoxy getting too hot and melting.

I did try pouring excess alcohol back out of the Sketti. This was not very successful. Some did come out of the jet holes, but the double wall construction means you can't just decant. This means that you should try to gauge the right amount of fuel to put in each time. This comes with practice - and maybe a small measuring container. I just looked in the base of the stove to see how much was there.

In short, this is a powerful and robust two-man alcohol stove at a quite low price. You can throw it in your pack with few precautions. The design is more than the amateur stove maker could create, unless he had a lathe and skills in rolling tubing. It will boil enough water to make a meal for two to four people, but forget simmering.

What's Unique

The Mini Bull Designs Sketti alcohol stove has features which are relatively uncommon, and the combination of features is unique. Mini Bull Designs offers other quite similar, but smaller stoves.

  • Rolled seams which don't leak or soften with heat
  • Big heat output, enough to cook for two or more people
  • Integral and very strong support for the pot
  • Low profile despite the integral pot support
  • Use of the pot to force a pressurised jet operation
  • Very light weight
  • Dead easy to get going

Recommendations for Improvement

The Mini Bull Designs Sketti has a lot going for it, but of course I have some recommendations for improvements.

  • It would be lovely if there was some way of throttling the stove, but it doesn't seem very easy to include such a feature.
  • Maybe the row of holes could be moved up a very small amount, or slightly reduced in number, to reduce just slightly the power of the stove.

Citation

"Mini Bull Designs Sketti Stove REVIEW," by Roger Caffin. BackpackingLight.com (ISSN 1537-0364).
http://backpackinglight.com/cgi-bin/backpackinglight/mini_bull_designs_sketti_stove_review.html, 2006-06-14 03:00:00-06.

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