This is a simple small marine engine.
The horizontal boiler is approx 2" diameter x 2 3/4" long and is made of copper. It is totally enclosed in a brass outer wrapper, which has holes for the burner and safety valve; and to allow the burner gasses to escape. The burner is a meths wick type using a 1" wide flat wick. The only boiler fitting is a safety valve. Steam is fed directly to the port face incorporated in the cast mazac(?) frame. The single acting oscillating cylinder is 9/32" bore x 1/2" stroke. The cylinder is in two parts; the barrel being brass and the top end, including the port hole, is mazac. There is a brass cup mounted on top of the frame with a small hole to drip oil onto the port face. The piston is connected to a cast mazac crank, with nominal balancing, and a 3/4" diameter cast mazac flywheel. The flywheel carries a pair of pins for driving a propeller shaft. As acquired, the safety valve and the burner were in need of repair. I have repaired the burner and fitted a Mamod S/V for the time being. Paintwork appears to be original and is in reasonable condition for it's age.| Make | Gem |
| Model | Marine Steam Unit |
| Made | c1946-47 |
| Description | Marine engine |
| Cylinders | 1 |
| Cylinder Type | single acting |
| Bore mm | 7.25 |
| Stroke mm | 12 |
| Valve Type | Oscillating cylinder |
| Boiler Type | Horizontal |
| Boiler Diam mm | 51 |
| Boiler length/height mm | 70 |
| Fuel | Meths |
| Mechanical Condition | Good |
| Cosmetic Condition | Fair |
| Paintwork | Original |
| Packaging | Cardboard box |
| Purchased | 31 March 2019 |
| Purchase cost | £155 |
| Additional spend |