Shipbucket

Just watched the BBC show Top Gear's review of the Ferrari FF, their first production all-wheel drive car. The FF's has 7-speed double clutch semi-automatic gearbox delivering power to the rear wheels and second smaller (and more limited as it can handle only about 20% of the engine's power) gearbox attached to the forward end of the crankshaft delivering power to the front wheels.

With trend in greater electrification would it be better to attach a generator on the opposite end of the nominal output shaft of engines on naval vessels. This should give a huge boost to the generating capacity of ships to run more electronics as well as more electromagnetic (railgun) and directed energy weapons.

Would the trade-offs in complexity and greater weight be worth it?

That absolutely makes no sense whatsoever. Literally everyone else just uses a transfer case, unless that's what you mean by "second smaller gearbox".
Ummm...you should look around the database (especially for cruise ships) and see their Azipods.

The FF does not have a transfer case. It has a second gearbox taking power from the forward end of the engine crankshaft. The forward gearbox can only be used up to fourth gear.
The few documentaries on the construction of cruise ships with azipods that I have watched, whenever the engines are shown, they have only the generators attached to only one end of the big diesel.

If you mean the database here on Shipbucket, I tend to skip over merchant vessels and stick to the naval side of things.

the only reason why you would attach anything to the other side of the engine is space. and not space saving, though, just the ability to 'play' with placements.
in engine setups on ships, you have an limit in length of the watertight compartiment, so it is an bad idea. keep in mind, you choose here for 2 10MW generators on an 20MW engine, or an 20MW engine with one 20MW generator. you gain no additional power or possibilities with this setup.

_________________
Drawings are credited with J.Scholtens
I ask of you to prove me wrong. Not say I am wrong, but prove it, because then I will have learned something new.
Shipbucket Wiki admin

and in fact you save more space to use one 20 MW generator on a 20 MW engine, than two 10 MW generators on a 20 MW engine.

Yes the two 10 MW generators can possible take less space than an 20 MW generator, but all those additional equipment to run those two baby's has to be doubled. And then it come to maintenance...

and if you take in mind clutches.....
and the best part is: if you want 2 separate generators, it is best to have an 2 ended gearbox on the engine, which enables you to attach both.... with less complicated construction and less space taken.

_________________
Drawings are credited with J.Scholtens
I ask of you to prove me wrong. Not say I am wrong, but prove it, because then I will have learned something new.
Shipbucket Wiki admin

suddenly there is no place for the GRAND captains cabin!

Speaking as an engineer, I can't really see the advantages in a marine setup. I'm going to ignore the small alternators found on the front end of small craft engines since I'm assuming that's not what you're talking about.
Now, there's two scenarios that presents itself, pure electrical generation and mixed mechanical and electrical.
In the first case you're better of just fitting a larger generator. Granted, at low power levels you'll be swinging a lot of dead weight around, but the lack of a gearbox should more than make up for the loss of efficiency. One large generator will also weigh less and take up less space than two smaller ones since, at mentioned, you don't need a gear box and/or a clutch and neither do you need to duplicate all the auxiliary systems.

In mixed setups we tend to use shaft generators. These are generators where the stator is wrapped around the main propulsion shaft. These are surprisingly compact and they weight less than a separate generator since it doesn't need its own shaft and clutch.

That said, mixed setups are, as far as I'm aware, entirely limited to civilian vessels since they put some pretty stringent requirements on your operating patterns.

_________________
“Close” only counts with horseshoes, hand grenades, and tactical nuclear weapons.
That which does not kill me has made a grave tactical error

Worklist

Source Materiel is always welcome.

Thanks for the replies.