Steamship Construction

[salsettediving]

A while back I stuck on some stuff for engines etc then deleted it by mistake. As a relief from wreck notes I thought from time to time I would build this post on steamships in general.In the wreck notes themselves if something techy crops up we can refer back here for enlightenment.
The Compound Engine.
Fitted to steamships up to the 1890's when they were superceded by the more economical triple expansion engine. The compound normally has 2 cylinders, a high pressure nearest the boiler and a low pressure. It is possible to look at the size of an engine and guess the size of a ship. The number of boilers also helps in this respect. Compound engines were very rugged and often saw service for 50 years or more. They were hardly ever replaced in a ship with a triple expansion engine as the shipowner would lose cargo space. Prior to WW2 nearly every ship engine was unique. Each engine was built for each individual ship. The set of cylinder sizes found in Lloyds Register are another useful way to idenify a ship. ( See Aeneas ).

[salsettediving]

With the introduction of higher pressure boilers and better condenser design it was possible to expand the steam 3 times. ( and eventually 4 times ). This engine is known as a triple expansion engine. It will have low , medium and high pressure cylinders. There could be 2 cylinders of the same size giving a four cylinder Trip. Exp. engine. These three cylinder engines are the most likely ones you will see on a wreck. The condenser changed the steam back to water but more important for efficiancy it reduced the back pressure on the engine.Each one will still be unique to the ship and remember the little cylinder is nearest the boiler and ships bow.Useful if you are looking for the bell.The wheel on the engine is a reversing wheel. Wrecks that have the engine broken open so you can see the piston are Baygitano, Moidart and Aeneas.

For a complete explanation of steamship engines see =
Steam at Sea by Denis Griffiths ISBN 0 85177 666 3

[salsettediving]

Will just keep this as one long thread. Will mostly be photos . Lets hope Photobucket stays alive for a good few years.

Standard Trip Exp Engine



Starting to get more complex.



Approaching the ultimate in design and scale. Eventually steam engines reached the end of practical development employing superheaters and auxillary turbines.Indeed even in Victorian times it was proved by "Turbinia" that steam turbines would eventually succeed reciprocating engines.



The condenser set up.

[Razorbill]

I`m lovin` it Nick.
Keep it up.

[salsettediving]

XXXXXXXXXXXXXXXXXXXXXXXX

[salsettediving]

Right Razorbill you asked for it. Never mind the doors I am going to blow your bloody socks off.

These and the other superb drawings are from the classic work "Illustrated Marine Encyclopedia" published in 1890 by Capt. H. Paasch a Belgian marine surveyor. My rebound copy cost me £70 some years ago.

[salsettediving]

Inside a Liberty Ship engine room.
Top.
Base of engine showing cylinder columns and connecting rods.
Bottom. Top of engine showing high pressure and intermediate pressure cylinder covers



Left. View down shaft tunnel from the engine thrust bearing. The tunnel runs through the after holds.
Right. Top of the cylinder columns from the intermediate walkway.At centre you can see the connecting rod crosshead and piston rod.

[Woz]

Cor that's proper engineering, that is. See that throttle valve on plate 51 above? Guess who makes them for a living?

[salsettediving]

Not for steamships !

Below is the usual type of ship a diver will see. Engines midships. Usualy the shaft tunnel itself will have rotted away by now but the shaft will remain. Wrecks with prominent shafting include Frigga and Chorley.

[salsettediving]

Typical divers view of a ships machinery space.



Proud of the engine they built.



Low pressure turbine installation. Not nearly so interesting !

[salsettediving]

Usual machinery space arrangement for a single boiler steam coaster.

[salsettediving]

Boilers.

As a very basic rule for ship sizes with a trip exp engine the following applies.

Less than 1000 GRT 1 boiler.
Less than 2000 GRT 2 boilers
Less than 3000 GRT 3 boilers
Less than 4000 GRT 4 Boilers

This is only an approx. guide but it might start you off on the right track for identification purposes.
Remembering that a gross registered ton is 100 cubic feet of enclosed space in a ship. Net tonnage refers to cargo space only.
Sometimes a donkey boiler confuses the boiler count. Usually they were fitted on the main deck or above but with the collapse of the hull they often end up near the engine room. The donkey boiler ran the winches etc when the ship was in port.

[salsettediving]

I er um have just built this model in my fish tank. It does give a good representation how many WW1 wrecks look today.Hull broken down . Machinery the highest point.

[salsettediving]

Typical divers view of a ships engine.

[resting rifleman]

what a bloody good thread
mike.

[salsettediving]

Thanks Mike. While I know some people like it I will keep it going.If it goes too long I may need to start a new one. Will wait and see.

Nick

[salsettediving]

A couple of GA's ( General Arrangements ) which show how a three island four hatch cargo ship and a trawler are laid out.

[Janos]

Originally Posted by salsettediving

Thanks Mike. While I know some people like it I will keep it going.If it goes too long I may need to start a new one. Will wait and see.

Nick,

Please keep going! I think it's great that you're sharing your knowledge in this way and I've learnt loads!

Janos

[salsettediving]

OK Janos. I think that I will call this section the engine room and start another thread called The Bridge.






The important bit at the back. The stern. Wrecks with impressive upright sterns inlude Miniota,Chorley, Romsdalen.

[salsettediving]

Divers view of a stern. Cribbed from my mate Pete Glanvill.