Vanguarding old turbines

[The Rock Doctor]

I yanked six pairs of 1905 turbines off the Lippe class protected cruisers between 1916 and 1918.  The ships in question were built with oil-sprayed coal machinery (90% coal) and a hull strength of 1.00.  Each set of machinery weighs 995 tonnes and generates 9,000 kw of power.

I want to re-use one set of machinery in a seaplane carrier in 1920.  The vessel is experimental, not fast or heavily armored, so there's a lot of unused internal volume and hull strength once I've plopped the armament, air group, and protection into the design.  I would like to re-use a set of the old, inefficient turbines to take advantage of this.  It would notionally save me money and BP.

However, the ship is to be oil-fired.  Even with the same 1.00 hull strength and 1905 engine year, the fuel choice changes the weight of the machinery installation from 995 tonnes to 914 tonnes.

So:

1)  Should I take some process - a refurbishment - to convert the machinery from oil-sprayed coal to oil?  If so, what would this cost?  For a whole ship, one would pay a flat 20% of total cast cost for the refurb, plus a cash cost based on the bunker weight to change the bunkerage itself. 

In this case, it's just pure machinery, no bunkerage.  Would the flat 20% cash cost - and only that - be appropriate here?

Or is it just easier to say, "You took out 1905 turbines weighing 995 tonnes, but it'll only add 914 tonnes when you stuff it into the new ship, don't worry about the difference?"

2)  Either way, I assume I would deduct the cost of the turbines from the total cost of the ship.  The BP savings would presumably be the actual weight saved in the new design (0.914).  Would I peg the cash savings as 1x BP or 2x BP, given that the latter is the cash cost of new machinery in a normal refurbishment?

3)  Would the re-use of the machinery - approximately one-third of the ship's displacement - also result in a reduced construction time of 1/3?  Or do we just assume I'm taking the same time period but paying less for it?

Thanks.

[Kaiser Kirk]

Talk about an interesting question.

1)  Normally the two things are split between systems, and not done separately. So the current rule format does not handle it well.

A) Yes - converting fuel is done under Refurbishment, altering fuel type takes some expenditure.

Logic : The old engines would consist of the turbines, then the boilers feeding steam to the turbines. The burning system on a coal-powered boiler vs. oil burner should be different.
So there are two elements - the feed system for the boilers, and the handling systems for moving them around the ship.

At this time, I suddenly have a use for the old book on maritime engines covering this...that I didn't buy at the booksale years ago. Somebody else scooped it up.

Conceptually : Currently the boilers and feed systems are set up to use powderized coal with a spritz of oil, placed on a grate system and incinerated.
Employing chains of workers to throw buckets of oil through that opening into the boilers would not have the same effect.  So while The steam portion of the turbine system would remain the same, but the boiler would need new feed systems. 

The coal bunkers would not ever exist in the new hull, so no conversion of handling systems is required.

B) Cost :
Refurbishment is the correct category.
There is no need to remove/replace superstructure and make a big hole in the armored deck to remove the engines, or move internal bulkheads around to fit the new machinery.
When you scrapped the old ship, you lost 85% of the BP value, which covers the removal of those features and exposed the engines.
The new vessel will have the engines installed as part of the normal construction sequence.
Therefor the overall 20% cost does not seem appropriate. 

Essentially, you're modifying only one subsystem of the entire Propulsion system,
while leaving the rest alone.

I have no real guide for how much that "Really" would take.
Therefore I shall use the change in engine weight as a guide for how much is effected.

In the example that is 995 to 914, a change of 81 tons.
Engine changes : BP cost = (tonnage/1000); $ cost = twice the BP cost.

so...0.081BP  and $0.162

I know,  a horrendous expense.
But I think one that is fair and repeatable.

2) You save the actual weight saved in BP, and the cost of creating that BP. So $0.914, 0.914 BP.
Essentially, you have saved on the cost of creating a new engine.

3) Same time period, paying less.
I doubt during ship construction that engines are piece-meal assembled on site. I expect that fairly complete engines are placed by crane in the hull prior to the strength deck being completed.
Therefore the construction time of the ship should be the same.

[The Rock Doctor]

I can work with that, thanks.