Hey Tanker Builder ???

Okay;

 No Problem. The majority of engineering spaces Aft today are NOT the Containers of the machinery of the past. Diesels by nature can be monstrous But the fact is some are no more than Normal sized but only turn generators that drive the ship's propulsion machinery. Kind of like Boilers make steam, Take up a lot of Room and feed it to Turbines to generate electricity to drive the ship!

 Some are directly driven by the Turbines. Some are driven by electric drives sitting on top of the unit. In the old days before my time and while I worked for a shipping company The propulsion Machinery was Mostly all aft. Such as in postwar Tank ships with the emergency Generators and main housing for crew and passengers being Midships.

 After the war when diesels became the choice for Power , well then the dynamic changed. Diesels changed the way man drove their ships. Understand one thing. Nuclear Ships are Not that far out of the realm of Steamships! Reactors develop boiling water that generates steam to power the turbines for propulsion. See, nothing Special.

 Todays ship has In many instances gone backwards. I have seen some container Ships lately with a Deckhouse way forward of Midship as well as the old full aft configuration. Engineering always full aft. Weight leveled out by Ballasting. Aft deckhouse Coastal vessels have the weight Bias astern because of the sheer weight of the engines. So fuel and seawater tanks are place along the bottom or sides to level the ship when light!

     Many shipping Companies for many years prefferred machinery Aft to increase the Ability to enlarge the cargo area. Also it reduced Shaft Length from Power rooms to Props. It used to be that shaft lengths, required the shaft to be turned over numerous times to avoid a warp in the shaft . By turning the shaft over they avoided this. BUT, this also requires either steam ashore OR on board for this purpose I.E. Donkey Boilers.

 The Steam era came up with many ways of handling this. Warships were built in such a way that most Multiple screw vessels had machinery spaces dead Center and dead Aft of the Fire-Rooms ( Boilerooms) so that is why for the most part Ship stacks were at the Locations you see. Uptakes couldn't be routed to far away for efficiency When the old Buchanan Style four Stack Destroyers for instance were around. The Engine rooms had Airlocks because they were pressurized to compress that air to the boilers. At the time Ships didn't have Blowers bringing vast amounts of air to the boilers which didn't have enclosing casings like later types.. All engineering thus was midships. Plus Coal Bunkers could hold more in the wider part of the ship resulting in a larger fuel loadout!

     P.S. The Shaft alley of a Victory ship in better that one third of it's length!! Nowadays some ships have Azipods.These act both as Propulsion units and Rudders and can turn 360 Degrees(All Electric) Just think of an outboard Motor with the Propellor in a Ring For Steering and the Power unit a Big electric Motor Within the hull!

    Awesome TB thank you so much for the info, as stated it was metely a curiosity question more than anything. I had completely forgot about gas turbines and reactors....yep good ol fashion steam lol, but the info you gave makes sense to me. See your good to have around

I've seen pictures of empty T-2s with the bow completely out of the water.

I rite of passage on the Jeremiah O'Brien is to go all the way down the shaft tunnel to the stern. It's about 150 feet long.

I did get a tour of a big Diesel Container ship engine room. There was a spare shaft and a couple of spare connecting rods in there.

Bill

It's rather amazing just how many propulsion configurations there are in use today. In addition to the old standard steam plant, driving either turbines or reciprocating engines, there is the steam plant that drives turbines that power generators that drive motors for turbo-electric drive. Then there is the nuclear plant where the 'nuc' part replaces the boiler(s), and then any of the above propulsion systems. Then there is the primary diesel plant, engine driving the shaft directly. Then there is the diesel electric plant where the diesel drives a generator which drives a motor. Then we can get into the gas turbines; jet engines which drive either the shafts or generators tied to motors. Then there are the azipods as TB mentions, which can be powered by a steam plant or a diesel plant, or a gas turbine plant.

and then there are sails and paddles. Take your pick. 

    As a former Navy jet electrician from a land locked state I believe I would like anything but wind or paddles LOL.

      I got a tour of the MMS #1 onboard Ranger CV-61 once, I remember it being very cramped, hot, LOUD, and it was a shock of how hard it was to open the hatch, actually just a door off the second deck, that led down to ther space. Felt like a vacuum was holding it shut. Saw the propeller shaft for I believe the #1 stbd screw....friggen HUGE!! Scary to think the entire ocean was being held back by basically leather seals and air pressure.

    Later on in that cruise I was on a working party aft and below the brig area, putting stores into a cooler space, I could actually hear the blades of the screw turn under my feet. NEVER want to be that close to the bottom of the ocean again.

Then you should try being UNDER a ship that size. Surprise, surprise, it's dark down there! If you swim all the way over to the keel, you can't see daylight in any direction; at least not in most ports! 

GMorrison

I've seen pictures of empty T-2s with the bow completely out of the water.

With a single screw ship "in ballast" where you are going to have one end or the other out of the water, it's better to bury the screw than the bow.

In the days of the old three-island tramp steamer, the prop would chug over as much as half out of the water, but the ballance would be about even along the keel. 

The big container ships put the bridge in the forward third as it's a good place to run the ship--good visibility for one.  Ahead of the CG, too, which makes steering clightly simpler. 

Those modern ships only need compartments of 15-20 crew, so, many are only accomodations from the 01 deck up.

Fashions in powerplants, as noted above, vary.  Large marine diesels were just that.  Three stories tall with 1 - 3 m cylinders on 5-6m strokes, and enough compression to run on raw crude.  But, it can be easier to just install 18 & 20 cylinder turbodiesels to sping gnerators--these are often just the same powerplants as locomotives.

In days of old, the line of the shaft deterined where the powerplant had to be, as it would be inline to the output shaft of a turbine or reciprocating engine.  Today, such things just have their reduction gears arrayed to get the out put power to where the shaft is.

The number of ships using azipods has also changed the axes for power, too.

  Thanks Capt82 helps expland on TBs reply very much appreciated.

    HooYaa, sorry my Naval brother but I will stick to being forever an Airedale....the hole in my boot tells me when it is time to swim LOL.

      No disrespect Capt82, your my Naval brother as well

      I might add that I wanted to be a boom operstor on KC-10s or a Loadmaster both AF ratings, I kinda got shanghied....literaly by a Chief Hull Tech when I wnt to enlist. I come from Ohadi..... North Ohadi.....public schools, sawmills and mines. Go figure.

I'm a big fan of Great Lake ships.  Bulk carriers there went to the aft machinery mid 19th Century. Scottish puffers were also early aft machinery.

Hi"G"

      Yeah, I could've gone there, But I thought my explanation was turning out like other posts of Mine-Kinda Long Winded! So I stopped there!

Yeah Rocketman2000;

 I spent part of my formative years in Buffalo N.Y. at grandma's house. The Lakers would winter up there. Long suckers for sure and the "Eddie Fitz" was the prettiest of them. Clyde " Puffers" were and are unique looking vessels. I understand quite a few have been saved from the Wreckers.

Hi! Hoo Yah!

  My answer to that is NOPE! Been under two big un's and one small one( Destroyer). Thanks but, No thanks! Seems the Can got a solid object in the primary boiler feed intake to the D.A.Tank. It was before Fram. Geez that was ugly.

rocketman2000

I'm a big fan of Great Lake ships.

Yeah, kind of cool to watch them pass under the Duluth Lift Bridge.

The 13 thousand-footers get a lot of attention, but there still are enough of the "three frame" bow-house double-enders on the Lakes. 

From what I've heard, all the steamers have been converted to diesel.

Yeah But

       They do tell a continous Maritime story of Utility vs.Change. Saddest of all was the length of time the same hatch system has been around.The same system responsible for quite a few " Lakers" Demise! Flat Plates with Clamps. Alright in Mellow weather. In a "Superior" Blow can be a death sentence!