Looking for a simple start.

[hartleymartin]

I'm looking for a fairly simple-to-build engine and boiler to suit a small launch. At the moment I don't have access to machine tools, but I am looking to obtain it here in Sydney, Australia - perhaps through some sort of engineering club or "men-in-sheds" program.

My (rather long term) plans are to build an Atkin & Co "MoToSkiff" hull and fit it out with a small single-cylinder engine, slip eccentric valve gear, small boiler, to run as a small pleasure craft. I am looking at options, and I may expand the design to 18' or 20', but I have nothing settled yet.

I suppose I'm looking for something in the order of 4-5hp. I'm not 100% about Australian steam boiler regulations, but I was under the impression that for certain uses we have a restriction of 100psi for boiler pressure.

The first stage of the project is that I would like to build a steam engine:

- Single Cylinder - I've looked at a few other launches, and many seem to have 2.5"x3" bore x stroke engines.
- Slip Eccentric Valve Gear - less parts to make, less parts to oil, quieter in operation.
- Maybe a cross-head feed pump for the boiler?

I would like a design that doesn't require me to purchase lots of expensive castings. Something that could be fabricated largely from bar stock would seem to be ideal, although I have seen a cylinder casting set for $125 which may prove economical.

Then I need to consider a boiler:

- Has to be big enough to supply steam for the engine (obviously, which is why I want to make the engine first)
- Has to be small enough to suit a hull which might be as small as 16' LOA
- Copper construction - can be silver-soldered rather than welded-steel.

All ideas and suggestions are welcome. I spent 4 years as an Australian Navy Cadet so I have some experience with basic seamanship and I have previously learned to use a machine lathe and vertical mill at a basic level.

[hartleymartin]

Perhaps something like the Murray Marine would be suitable for my purposes:

http://www.strathsteam.com/page5.html

[barts]

Consider http://hasbrouck.8m.com/eng10.htm

or do like I did - convert a refrigeration compressor to steam. I ran mine for 20 years until the bearings gave out...

- Bart

[cyberbadger]

Have you tried to contact anyone from the Steam Boat Association of Australia?
http://www.steamboat.com.au/

Might be a good place to start....

They have classifieds and maybe a member could let you use their machine shop or show you the steam boating ropes?

-CB

[fredrosse]

A 1.5 to 2 horsepower engine will work well in your 16 foot hull. That can be made relatively easily from a single cylinder IC engine, built with a new cylinder head. I have made this conversion in 2 days with only hand tools, a small power grinder, and a hand electric drill, plus files and, of course, a hammer. Also need some simple silver soldering. Better yet, a two cylinder air compressor, with a new head, similar conversion. Virtually the same as Bart is recommending. Then you can at a later date replace the engine with a more traditional machine. The engine will require about 75 PPH (pounds per hour) steam flow.

Your boiler will require about 15 (watertube boiler) - 25 (firetube boiler) square feet of heat transfer surface area, and steel silver solders just as well as copper, so you could use either material. Welding would be better for the steel boiler, and silver soldering might have corrosion issues if the boiler is not looked after carefully.

Best wishes for your project, and get much advice here, or in you native lands.

[hartleymartin]

As much as converting another engine for this purpose is tempting, I'm really rather keen on building an engine from scratch, preferably from bar and round stock on a machine lathe. I've recently learned that quite a few milling jobs can also be done on the machine lathe, although it would be convenient to have access to both!

I've been watching Keith Appleton's series of workshop films on YouTube. A most interesting fellow. Turns out that I'm a bit like him in that we're both musicians with an interest in engineering.

[Mike Rometer]

The Ray Hasbrouck engines that Barts has recommended are designed round using no castings, everything is fabricated, or cut from solid. Of course some machinery would be needed but a simple lathe will do an awful lot with some ingenuity.

[hartleymartin]

The Hasbrouk No.10 Engine has caught my attention and looks like a rather attractive project. Although I think I'll stick to a simple slip-eccentric valve gear (less bits to make, less bits to oil).

[hartleymartin]

Having ascertained that about a 2HP single-cylinder engine would be sufficient to power a small 16' launch, a boiler to match this needs to be considered.

http://www.tinypower.com/store.php?crn= ... how_detail

This "M" boiler looks like an attractive option, being relatively small in overall size, 30 sq ft of heating surface not including a superheater, but I don't know much about how hard it would be to build one. All-welded steel construction means that I'll probably have to pass the plans to a welder and have it made for me.

[url]http://www.tinypower.com/store.php?crn= ... how_detail[/url

Something like this small vertical fire-tube boiler might be a more realistic option. This would be simpler to construct in copper as the tube plates are flat, the tubes are parallel and the whole thing can be silver-soldered (I think that's the term for it). The only trouble is that copper is fairly expensive, but I'm lead to believe that they are a bit lower on maintenance than steel boilers, and they are not as badly affected by sulphurs and such in the fuel.

I'm looking for something that is relatively simple to build, will supply plenty of steam for the plant equipment and will not require too much in the way of maintenance. Hopefully something that also steams quite well so I don't have to tow a fuel barge with me!

I suppose another idea to field at the moment is simple conversion to gas-firing. Some sort of burner or set of small burners which could simply sit on top of the fireballs and be fed from a gas cylinder like the ones used on barbecues. I'd prefer to burn wood or coal, but it is a possibility I should at least consider.

[Lopez Mike]

My advice:

I would not bother with any boiler material but steel. Silver soldering a complex structure like this is a nightmare. I have done it once and will never do it again. The heat transfer advantages of copper alloys are illusive at best. And the differential expansion of ferrous v.s. non ferrous materials is significant.

Make it out of steel. Have the welding done by an experienced welder. Roll the tubes in. Perhaps a TIG sealing weld on the ends. A rolled tube is easy to replace. A licensed pipeline welder can handle it if you can't find an experienced boiler welder. The welds on pipelines are done with a TIG root weld and 7018 filler. Nothing else is being done on pipelines. They operate at pressures far, far beyond anything you will ever see.

Have a discussion with the prospective welder before you cut any steel. If he does not specify certain clearances and shapes for a full penetration weld and does not seem aware of such things as the tube sheet and mud ring being recessed, smile and find another welder.

Build it with a water leg. Much simpler than a bunch of refractory. This was beaten to death over a hundred years ago.

Save yourself a lot of effort, expense and grief and build a very ordinary boiler. Copy a Beckman VFT. They work. I have one and I have zero complaints.

I know less than zero about water tube boilers. Others here can illuminate the subject for you. They work fine too. Just a different set of design and welding skills.

Sorry to sound so rigid and dogmatic but we see this here again and again. A new person trying to invent the wheel. It is a significant project to complete a launch. And equally as much work to design some unusual power power plant with illusive advantages. Most of us enjoy complicated and unusual machinery but usually on someone else's boat.

Mike