Question about modern naval ship propulsion

Many years ago I served in the Black Gang aboard USCGC CONFIDENCE (WMEC 619), home ported in Kodiak, AK at the time. The CONFIDENCE was originally built with 2 Cooper Bessemer 1500 hp Diesels, and 2 gas turbines.  The turbines had been removed before I reported aboard.  The cutter could make about 17.5 knots on Diesels; on turbines, she could make 18 knots but used 3x the fuel.    The cutter had JP-5 tanks with piping to the engine room and the flight deck.

While the gas turbines provided a higher shaft hp, the top speed didn't increase much due to the hydrodynamics of the hull.  

I love it. This stuff fascinates me.  Thanks again, guys.

 Chris

Was talking to my Snipe source and he will never miss 1200 psi plants. The gas turbines made life much easier. You hit the start button on the LM2500 and you can go to full power instantaneously compared to the 1200 psi systems.

At this time USN boilers, gas turbines, and diesel engines are check out to run on Naval Distillate fuel. The NATO designation is F-76. Gas turbines can also use JP-5 (NATO F-44). A higher viscosity version of Naval distillate (F-75) can be used if necessary.

The F-76 is in the range of commercial MGO (marine gas oil), the F-75 is in the range of MDO (marine diesel oil).  The fuel is filtered to reduce the amount of silicon, and metal impurities. 

More than you wanted to know data dump concluded.

All sorts of tales from the snipes on how, with 400# & 600# steam plants, a person could find leaky flanges or steam lines could be found by passing a raised-up broom along the lines.  When the broom is tossed out of the striker's hands, the 3/c sent along can go back and report the location to the Chief Snipe.

With a 1200# plant, the broom would take arm and the broom from the wielder.  That, and a steam leak facing the hull would bore a hole through the plating.

Not much missed, by most accounts.

The General Electric LM2500 is the most common USN aeroderivative gas turbine.  The 1200 psi steam systems are universally loathed by my sources.  Boilers and steam turbines, replaced by one system, with lower manning and operating cost.

Gas turbines in the USN are fed Navy Distillate a cousin of diesel fuel.  Aeroderivitive gas turbines can also be fueled with LNG, natural gas, or powdered coal. 

http://www.geaviation.com/marine/engines/military/lm2500plusg4

Don't give me any huge credit--I'm SWO, I've only a couple semesters on propulsion, and from sharing a compartment with a snipe or two. (Which can be a sweeet deal, they are never on the same schedule as the rest of us--other than they all seem to snore--loudly--and smell indelibly, of POL :-) )

Wow, this is some great info. Thank you all, esp. CapnMac!

Used peanut oil on a jet engine mounted on a back of pickup going down M23 south of Ann Arbor, MI in 1984.  Found the engine in a junkyard the U of M discarded.  If was a lot of fun doing 100 mph.

One of the neat things about gas turbines is that they will run on just about anything that burns.  There was the jet engine company in Walled Lake Michigan (forget the name, now) who invited a bunch of people, including press, for a ride on his little gas turbine boat, and announced they were running on salad oil!  Jet fuel is not that different from diesel fuel, both basically kerosene.  In fact most jet engines will run well on kerosene with just minor adjustment.

Needless to say , whatever it was , I stayed away from engineers coming off duty .Gees , watta crabby bunch .Nary a smile EVER ! And B.P. Paid them well too !

That I have no idea, was a radarman and was not familiar with that.

Was that a 400# or a 600# plant aboard that T2?

Grew up hearing all about the "newfangled" [insert colorful language] 1200# plants and care, maintenance, & cohabitating with same.

I was on an T2 Oiler in the mid 60's, spent 3 yrs. on her. I am sure the contents have changed since then. We carried a lot of Avgas, oil, etc. on her. Fueled many a ship, carriers, DDG, DLG, DD, etc.

Depend upon the ship and era.

The modern smaller combatant vessels--FFs, DDs, CGs--use a modified DC/MD-10 gas turbine fueled by Navy Distillate #2.  Which has a passing resemblance to kerosene--for far too much info, see here: en.wikipedia.org/.../Fuel_oil)  That fuel can also be used in the various diesels used, too.

Support vessels and large combatant vessels run on steam generated either by bunker-fired boilers, or fission powered heat exchangers.

We refer to the storage spaces as bunkers as a legacy of the time when coal was the power at sea, and it was bunkered in spaces formed between the ship's frames.  The tankage is still formed by closing up the voids between frames, and plumbing them to the engineering spaces.  (some of the frames are doubled or trippled as needed.

There are some very good stability reasons to use skinny tanks wrapped around the ship--much too complicated to go into here.

After much experimentation, USN has gotten out of the combined (hybrid before it was cool) engineering strategies.  While a good concept, it has a flaw in needing a much more complicated set of reduction gears to connect the various powerplants to the propeller shaft(s).

Turns out that CODAG is very handy in patrol craft, though--you set up a diesl on the centerline, and run a pair of gas turbine plants on both outboard sides.  Any drag from the turrbine running gear is offset by the cruise efficiency from the diesel plant.  (Or, you rig up a set of disconnectors at the reduction gears and let the idle shafts freewheel.

Marine diesels have improved in amazing amounts in the last few years.  Most will will now run on raw crude (which is a tad easier when the cylinders on a in-line marine six-cylinder have a diameter near 1 meter, with a 2 or 3 meter stroke supplying plenty of compression).

they use jet fuel just like the airliners use as it is a navalized airliner engine. is stored in tanks like in your car.