On Apr 22, 9:04*am, (Richard Casady)
wrote:
On Tue, 22 Apr 2008 09:22:08 -0400, "Roger Long"

Big ships all have direct drive engines. If the engine in running the
prop is turning. You stop it and restart it turning the other way for
reverse.

Casady


Hello Casady:

Well, what can I say. Im going to cosider anything big as 500GRT.
What are some the engines Ive seen on these boats.

Of course there are the old air start reverse diesels ya might be
thinking about. If your going forward and want to go revers then ya
got to kill the engine and restate the engine in reverse. makes for
interesting manouvering at the dock.

Lets try steam as in the SS Ocean Phonenix: boil water and run steam
through turbin. Lots of ways to boil water.

HOw about EMD...... (Electric Motor Division) There, like the railroad
locomotives, the engine runs a generator that then supplies
electiricty to an electric motor which then pushes the boat. Just
manage the electric motor.

NOw there are a couple ways to do this all.

1) Z drives can swivel 360 degress so no need for a marine grear
(transmission)
2) varriable pitch props. There ya can just increase/decreas shaft
turns and fiddle with pitch contorll.

So me thinks there are a lot of options you may not have considered.
But thats okay, ship propullsion systems is an interesting subject
changing annually.

I think ya best stay talking about ur recreational yachts and leave
the big stuff to thoese who have actually been on one.
bob