Wichmann
Semi-Diesel Engine
Horsepower: 83 @ 250 RPM
Torque: 1,747 foot pounds @ 250 RPM
Cylinders: 2
Bore: 12 5/8"
Stroke: 12 5/8"
Weight: approximately 6,000 pounds
Type: Two-cycle, naturally aspirated, reed valve induction, dry sump, Bosch-type injection using hole nozzles
This engine was built by the Wichmann engine company in Bergen, Norway, during the 1930s. it is typical of many large engines built for recreational and commercial uses in Europe and America after Rudolph Diesel perfected the high-compression crude oil marine engine about 1910. Crude oil is not volatile and dangerously explosive like gasoline, but it requires high pressure to combust and a heavy engine to withstand the pressure. Semi-diesel means that the engine is initially fired by a heat source - either hot tubes or glow plugs - rather than by the heat generated from the compression alone, as in a true diesel.
Compare this engine to the large steam engine on your left. Diesel engines have several advantages over steam. Smaller, lighter, and easier to maintain than a steam engine, they are started and shut down more quickly and require fewer crew to operate. Diesels are safer and more economical than comparale gasoline engines as well. That is why most vessels today from supertankers to yachts, are powered by diesel engines.
Although it has low horsepower, the engine's torque provides efficient propulsion with a propeller four to six feet in diameter. One of the engine's most interesting features is its direct connection to a controllable-pitch propeller. This provided for reverse by changing the pitch of the propeller rather than reversing the direction of rotation. The pitch (angle) of the blades was changed by a push rod in the hollow propeller shaft.
Mystic Seaport acquired this engine in 1992, but its poor mechanical condition called for an extensive restoration. Museum volunteers devoted 3,300 hours over two years, dismantling the entire engine. They manufactured numeous parts, using the originals as patterns, and restored the engine to excellent working condition.
ID# 1992.65
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