S.L. Otasell

Owned by Wally Mounster of Hobart, Tasmania


17 feet long, clinker built from marine ply and has a half cabin.


Three engines have been built, the first two were not completely satisfactory. The current one is a two cylinder vee simple with poppet valves, eight valves are operated by a cam on the crankshaft. This cam has two tapered lobes and by sliding it along the crankshaft the cut off and the direction of rotation of the engine may be changed.


250 feet of stainless steel tube in a coil shaped like one of the old fashioned bee hives. It has about 40 sq feet of heating surface, it is wood fired using natural draft, safety valve is set at 1000 psi but pressure is normally about 400 psi, steam outlet temp is 400 degrees C.



During the last 20 years the boat has been used as a floating test bed for Wally's monotube boiler and poppet valve engines.

Feed water is supplied by a variable stroke pump which is adjusted to regulate steam temperature, steam pressure is controlled by a damper which automatically closes off the combustion air as the pressure rises.


Click on these thumbnails for a larger view


Otasell's twin vee-simple poppet valve engine