Steam Happens 12: Concept Model of A New Engine

CAD drawings, photos and movies

I like a compact, nearly silent engine.  To me there’s nothing more peaceful than seeing a steamboat move across smooth water with neither wake, noise or fuss.  A V2 simple is a good choice for a small boat.  It tucks behind the boiler nicely maximizing cockpit legroom, runs very smooth at all speeds, is self-starting with no stalling centers and has a very low center of gravity.  I have designed an engine of this type with a few new features:

Both cylinders cast iron of identical size and configuration for simplicity of machining.

Balanced D valves to minimize valve drag (and its resultant power consumption). 

A smooth, lever-operated, sliding collar slip eccentric reverse.  This should ensure silent operation and eliminate the clatter often found in worn, complex linkages.

And, of course, the use of sealed ball bearings, roller and needle bearings wherever possible to minimize on- the-go lubrication and bilge oil contamination.

click on the above drawing to download a .dwg file for viewing with CAD software or eDrawings

eDrawing viewer is a free .dwg and .dfx view available at  

a .dfx version of the drawing file is available here




A few pictures of the balanced "D" valve

The valve face is bolted to the valve body and can be quickly modified or replaced

It is the square bronze part in the photo below

Note the tapped pressure equalization passage connecting the exhaust plenum (square inner chamber) to the balanced side of the valve

The back or balanced side of the "D" valve

The white delrin ring seals against the ground surface of the steam chest cover.

The area inside this ring is at exhaust pressure because of the threaded equalization passage.  In the photos above and below the equalization passage has been blocked by a setscrew.

The D valve is now in normal (or unbalanced) operation.

In case of a delrin ring failure, blocking the equalization passage (by inserting the setscrew) will return the steam chest cover side of the D valve to high steam chest pressure. This will allow you to continue engine operation.


The delrin ring is lightly pressed against the inside of the steam chest cover by an O ring.

High pressure steam will enter the O ring area and further seal the delrin ring against the inner side of the steam chest cover. 


The delrin ring will probably be replaced by a cast iron ring


You can download movies of the engine operating under compressed air below

These are very large files. 

Do not attempt to download these files unless you have a broadband connection

click here to download a movie of the engine reversing at low speed

click here to download a movie of the engine reversing at high speed

Click on the picture below to see this engine running in Al Berry's boat, Derelict