Originally Posted by Ex Sailor
Interesting question .... I would think that all engines rotate only in one direction and the rotation is changed by the gearbox ... no ?
That is not the case. Many diesels were counter rotating. Many of those engines, the counter rotating ones, are still around, in twin engine boats.
Although I have a single diesel, older engine, my engine model has standard and counter rotating models depending upon whether the boat was a single or a twin.
That has changed in most cases so now the newer engines all turn the same way with the shaft rotation change done by the gearbox.
The same goes for many gasoline engines. My previous boat had both types, standard and counter rotation.
The suggestion to try to crank the engines will tell you if you have a counter rotating engine. Just a bump will be all it takes. If one turns one way and the other turn the other way you have a counter rotating engine.
While looking at the FRONT of the engine where all the pulley/belts are:
-- if the engine rotates clockwise the engine is standard or L.H. rotation.
--if the engine rotates counter clockwise then it is counter or R.H. rotation.
THe determination is actually done at the flywheel but since most of us cannot see the flywheel this is acceptable just keep in mind which way those pulleys turn on which engine.