The Steamboating Forum

Hi Everybody

Still lacking access to the workshop I have been idly mulling over a letter in the Steam Boat Association's magazine Funnel issue 184. In it, a fellow Forum contributor, Greg suggested that the SBA ought to address the difficulty of getting a new boiler at a decent price since this is one of the most significant blocks facing aspiring steam boaters. The are plenty of good boat designs and plenty of engine designs, not to mention ready made hulls and ready made engines. Boilers, however are thin on the ground.

My mulling has gone like this. Firstly what size of boiler would be sensible for building in quantity? My answer to that is one that would support the smaller launch in the 16 to 18 foot range since that is the sort of size that younger working people might be able to afford. The reason behind that suggestion is that we need to keep getting younger people joining our hobby or it will fade away as we old wrinklies fade away.

The second question is what design would best suit modern mass production methods? I am assuming that it would be a water tube design, but this is where the assembled expertise of this Forum comes into play. The SBA's WTB1 twin drum design might be the right size but all those copper tubes expanded into the drums sounds like a difficult object to make. The Blackstaff Wood suffers from similar issues and then there is the Ofeld which is nice but not easy to assemble.

The third question is how many would be a sensible production run for a manufacturer? Are we talking 100 or perhaps 200?

The fourth question is how this project might be funded. For that I do have some ideas. I suspect that the majority of steam boaters are retired or heading in that direction. They all seem to have had interesting and well remunerated careers and thus might be deemed to be 'comfortable'. We also know that with the Covid 19 crisis badly affecting the economies of most countries, interest rates are going to remain at very low levels for some time. Thus holding cash is not a very good financial strategy. However, most of us are not fixated on our savings. That must be true or we would not run steam launches. It seems likely, therefore, that a good many of us might be willing to stump up (say) £1,000 as a long term loan/gift to the project. The other possibility is for the design to be oriented to renewable bio fuel firing such as wood and hence be marketed more widely as a green power source. That route might possibly generate some external crowd funding.

The fifth question is to do with location or locations. It would no doubt be possible to get boilers made cheaply in China or some other low wage country. However, my feeling is that it would be much sounder to make them on the continent in which they are to be used. Sea freight may be cheap in C02 per Kg carried, but total shipping emissions are a serious issue. Would it be sensible to have a single agreed design that would fit with all pressure vessel regulations around the world and then build them more locally, eg. one set in the US, another in Europe, etc. This would mean that production funding would be more local too.

There may be other things I have missed, but over to you all to ponder and respond.

Regards

Pete

I would think that a simple VFT would be appropriate. My USA steamer has a simple "Stanley Type" VFT, 16 inch shell diameter, 3/8 wall, 48 tubes 1-1/4 OD x 0.095 wall, 18 inches height. 20 square feet heating surface, producing 60 pph at 100 PSI from 70F feedwater. All welded construction.

This design is about as simple as it gets, meets ASME Boiler Code, and could be produced economically. I think the slower response of a VFT, compared to a water tube boiler, is an operational advantage, especially for beginners.

I agree with Fred. Make it a VFT. The intended use will be a first timer. Leave the cross/reverse flow, monotone, internal pump, supercharged whiz bang stuff for a later project when disappointment and teething problems won't be so devastating.

With the advent of CNC to take care of the tediousness of drilling tube sheets and with welding in the tubes, many potential users could just take a computer file and go seek out a machine shop followed by another trip to an experienced pressure vessel welder.

One of the main ways to get in trouble with a boiler is home welding and designing. It would go a long way towards pleasing regulatory organizations to see a design on paper along with the associated calculations.

While I appreciate the lower weight and perhaps better efficiency of a water tube design, I find the complexity daunting. Leaks happen at connections.

Though I don't think it's as critical, the slow response of a VFT is a plus even for an experienced operator. Combined with a hot well float, the power plant just runs and runs.

Now the slow response can be a disadvantage when making short passenger hauling runs at an event. You need to plan ahead for stops and starts. I fire with wood and I find that saving up my dry cedar and other such rapid burning stuff helps a lot. A fire that can be calmed down more easily helps. A low glass helps too.

In order to promote steamboating, I will volunteer the drawings and the ASME Boiler Code calculations for the boiler mentioned above, unless there is an alternate design that might be better suited to a small steamer. Lets discuss.

As a matter of fact, just last week I was in the "candy store for machinery and steel" (Glick's in Fleetwood PA), and discovered about 2000 feet of new A178 boiler tubes, 1 inch OD x 0.095 wall. I bought about 200 feet, a bargain at $0.45 per pound. Then I contacted an industrial pipe supplier, and found some "drops" (very short pieces of big pipe, left over from previous sales) in 16 inch OD x 3/8 wall, A106 seamless, and I bought three pieces to make three VFT boilers. These will be 16 inch OD, 18 inch high, with about 30 square feet heating surface.

The reason I decided to move forward with this is the ease of getting CNC waterjet cut tubesheets for a very reasonable price. E-machine shop (on the internet) quotes about $1100 per tubesheet, vs about $75 with waterjet cutting. I don't know if I will get the waterjet tube holes just over 1 inch diameter, cut with a big chamfer to allow full penetration welds, or to get the waterjet cuts just below 1 inch, and finish ream the tube holes myself to allow conventional tube rolling.

The original pressure vessel shell for the Margaret S. Boiler, a simple Vertical Firetube (VFT) made in 2010. 16 inch OD x 18 inch high, 48 tubes, 1-1/4 OD x 0.095 wall. 20 square feet heating surface, 60-80 pph steam output.

This boiler was designed and fabricated to the American Society of Mechanical Engineers (ASME) Boiler Code, and could probably be modified to suit British, and EU requirements, while still complying with ASME. Who among us has technical knowledge about British and EU boiler design requirements?

Fred, You know more about this than many reading here, but given the choice and based on my exposure to the subject, I'd go the welded tube route. Have many instances of hearing steamcar folk bemoaning the issues of rolled in tubes. Typical causes, low water and hard firing.

-Ron

On a recent locomotive boiler I rolled in the tubes since it took no time at all and kept the two tube sheets aligned nicely for welding into the shell. But I then did a TiG sealing weld around the end of each tube. And I still had two tiny weeps due to my beyond amateur TIG skills. Took five minutes to touch them up.

Lest one get the impression that I am a welder (hah!), all of the rest of the welds were done by a certified pipeline and pressure vessel welder. TIG root welds followed by filling in with 7018 stick work. All starts and stops ground out all that.

These locomotive boilers are funny to see. A major goal is to have weight on the driving wheels. The locos are almost always bothered by wheel spin. The effect is to end up with a boiler that, except for the fire tubes, could easily be used for a scuba tank. I mean, what is the safe working pressure on a schedule 80 8" pipe? Almost 1500 p.s.i.

$75 bucks is really inexpensive to have a tube sheet done. I'm impressed.

Having done several over the years, and at times when I had very little cash and lots of time, I can attest to the fact that beyond good control over the diameter of the holes, the rest can be low precision. I have laid out the array with a straight edge, compass and scriber, hand center punched the locations, and then starting with a center drill and progressing through a 1/4" twist drill up through a nearly 1" drill, then finished with a reamer. I suspect that my locations might have wandered as much as a 1/32" or maybe a bit more. I generated a pile of chips and spent several evenings. I used a vertical mill as a drill press but finding someone with a large drill press that can slow down to perhaps 100-150 r.p.m. would suffice.

These were sheets only 10" and 12" in diameter fitting into well casing that wasn't all that round (as much as 1/8" out of round) so I had to do a bit of work with a hand grinder to get my fits for welding to the shell.

My personal bias is that if you are uncomfortable cranking up your hydro test to 1.5 times your safety setting, you've cut the corners too close.

It's not rocket science. Just don't do your own design and welding. Or let me sell tickets if you do. NASA has openings for low wage pressure vessel testers maybe?

Hi Fred and steamy Friends

Thanks for that very kind offer Fred. As a small contribution from this side of the pond I will chase up the equivalent boiler, if one exists, in the SBA designs library. I am assuming that one exists, but being locked down away from my library I cannot look it up.

Can I also suggest that we should add into this the base (if that is the correct term) on which the pressure vessel would sit and then the 'bit at the top' under the funnel. I am also envisaging the idea of making some suggestions for the valves that will need to be fitted, the water gauge, the stem drier, etc. which could be laid out as a table. Thus one column could be European fittings, another US fittings and so on. I am not at all clear on the prevalence of BSP and NPT threads around the world, but I am sure that readers will prompt us.

The idea is that the documentation will enable the new entrant to almost work down the list and get stuff as funds permit. I guess we also ought to draw up things like fire door and latches, fire bars, ash pan, insulation fitting and fixing, etc. either as separate drawing or part of the main drawing.

However, since this is a cooperative endeavour, I would be pleased to what you all have to say.

Regards

Pete

Hi Folks

A further update for you with this idea.

It seems that the SBA boiler design library does have a firetube design for an 18" diameter X 24" high pressure vessel that was drawn up by David Beale. I have been passed a couple of pictures for Fred (coming to you later tonight or tomorrow Fred). There is positive interest which is encouraging.

As an exercise I have downloaded a chunk of data from the old SBA Steamboat Register (the up to date register does not allow a search by length of boat strangely) for boats of 18ft and less. Using that data I have worked out the steam consumption in lbs/hr (E & OE!) for all their installed engines. My first impression is that a lot of the boats are over engined, but see what you think. My intention was to get a feel for the typical smaller boat engine but this has not really achieved that goal. More work required I expect.

Getting late so that is it for now.

Pete