One day I got to help start a big old Cleveland, 12-cylinder diesel in a
surplus US Army harbor tug. What a great experience!

The engine stood about nine feet high and
had to be about 15 feet or so from end to end.

Chuck,

Stop by my boat one day and we can fire up the main. It is an Enterprise
6 cylinder with direct air start. Its about 7 feet tall and 15 feet long
as well.

The process is to fire up the 120 volt DC diesel generator, start the
starting air compressor, start the prelube pump, open the cylinder test
cocks, bar the engine over by hand with a long bar on the flywheel, roll
it over on air, close the cocks, put on the ear muffs, roll it on air
with the rack engaged and then smile a lot.

The "compression relief" valves are actually cylinder test cocks which
are opened to roll the engine over before starting (to insure the
cylinders are free of water or oil) and to attach a firing pressure
guage to record firing pressures from time to time. It is not normal
practice to start the engine with them open. It can be excting when one
is inadvertently left open as they shoot out spears of flame and make
interesting sounds.

Remember that lovely old wooden minesweeper you were on in Port Orchard?
The (previous now that it has been sold) owners also have a newbuild
vessel with a pair of those Clevelands with stainless steel crankcases,
bronze accessory cases and reduction gears. They have air start but via
an otherwise normal ring gear driven by an air turbine starter as is
more common on smaller engines.

Many years ago I sailed for a few years on a diesel-electic submarine
that used 4 of the 16 cylinder version of those engines. Don't miss them
much. Have some good tales of delivering that boat with the SS
Clevelands from Florida to Seattle and then operating it in Alaska.

Rick