The Steamboating Forum

I have started construction of a 1/48 scale waterline model of a small freight sternwheeler. The model is a kit produced by Kitwood Hill Models, and is based on illustrations from the 1902 catalogue of the Marine Iron Works of Chicago. See http://www.kitwoodhillmodels.com/50ft-river-steamer/

I have a couple of questions about the power plant, which are not obvious from the catalogue drawing to me or indeed the kit´s designer. I do not expect anyone to have specific knowledge of this particular boat type, but I want my modeling to be based on sound engineering principles of the time.

- How – and where - would water be injected into the boiler? The kit shows a feed pipe entering through the steam dome, which does not feel right to my (uneducated) intuition. Mechanical pump or a steam injector?

- How would speed and direction of the paddle wheel be controlled? By a mechanical linkage from the regulator back to the cylinders, or by a control valve near the boiler with separate steam pipes for forward and reverse?

- Steam exhaust from the cylinders? Closest route outside, tall pipe exhausting above the cabin roof, feed back to main stack to improve draft?

After sailing for 35 years I am reasonably familiar with general principles of maneuvring a boat, but I am a total novice to steam propulsion.

"- How – and where - would water be injected into the boiler? The kit shows a feed pipe entering through the steam dome, which does not feel right to my (uneducated) intuition. "

ANS: A feed pipe dumping the water into the steam space was used to avoid cold feedwater impinging on the boiler plates, as this could cause stress and strain on the boiler plates. Many boilers use a feedwater connection into the boiler water space, and these connections should have an internal distribution pipe to prohibit cold feedwater impinging on the boiler plates. Feedwater connection and internal distribution pipe within the steam space is one method often used.

"Mechanical pump or a steam injector?"

ANS: It would be common to have both methods available, however this type of boat, because of its slow engine speed, would typically have a long stroke piston type feedwater pump connected directly to one of the crossheads of the main engine. This would be the normal method of pumping feedwater into the boiler for this size boat. Larger western river steamboats often used the "Doctor", but that is another story.

"- How would speed and direction of the paddle wheel be controlled? By a mechanical linkage from the regulator back to the cylinders, or by a control valve near the boiler with separate steam pipes for forward and reverse?"

ANS: A steam valve (or regulator) is not used to reverse the engine. The valve actuating mechanism, generally consisting of links and levers operating the steam admission and exhaust valves on the engine was universally used here. Only one steam pipe from boiler to engine. There are volumes of information about this subject, look up "steam engine valve mechanism" to get some of this information. Use of a regulator, generally having a valve which puts steam into the normal engine steam inlet, or into the engine exhaust connection, reversing the engine, is very inefficient, and as far as I know, only used on toys and small model boats.

"- Steam exhaust from the cylinders? Closest route outside, tall pipe exhausting above the cabin roof, feed back to main stack to improve draft?"

ANS: Usually steam exhaust out of the engine and directly up thru the roof. On riverboats I have never seen exhaust into the stack to increase draft on a riverboat, although it could be done, as in railroad locomotive practice. Many modern steam launches have a small main steam (high pressure steam) pipe into the stack to increase draft when starting the fire, or pushing the boat for maximum power, but a riverboat as shown on your model would probably not even have that feature.

"After sailing for 35 years I am reasonably familiar with general principles of maneuvring a boat, but I am a total novice to steam propulsion"

Hope you can get involved with steamboating, it is a simple, and very satisfying boating experience, silent and free of vibrations always associated with motorboats. Making a fire and silently propelling along the river is much fun.

There was a locomotive patent taken out, I believe in the late nineteenth century, that consisted of spraying the feed water onto the surface of the boiler water up near the front of the boiler. The advantage claimed was that the dissolved solids would precipitate out in a form that would settle harmlessly to the bottom of the boiler rather than coating themselves on the shell, firebox and tube/flues.

(Locomotives in the U.S. were sorely plagued in many parts of the country with frightfully bad water supplies. Constantly needing to be blown down in service and subject to almost weekly boiler cleaning.)

Typical nut case inventor who, A: didn't know much about chemistry and, B: Never even built a working unit. To my knowledge it was never used in service. Another entertaining patent to puzzle over.

Thanks for the helpful answers!

Lennart Elg