Modeling auxiliary Diesel generators / powerplants

[Kaiser Kirk]

So....
I'd like to have Aux diesel engines which can power my ships electrical grid at a minimum.

1 ) If the vessel does not have turbo-electric drive there seems to be two ways
      1A : -Add a fractional bit of speed, and a little additional range.
             -Note that the .xx speed represents the diesel plant, and the 'n' nautical miles the fuel - note the fuel tonnage.
             -pay the 30% cost of the diesel plant in misc wt.

              Advantage : Wt is where it should be, so probably a slightly more accurate model, and the fuel reduces your light tonnage ever so slightly.
OR
       1B: Allocate some misc wt for one or both.
             It looks like 42 tons is 1000kw for a 1928 Diesel , so 54.6 tons would cover a 1000kw generator. One could scale up or down.

             1B(i) : Pay misc wt for the fuel
            or
             1B(ii) : again allocate 'n' nm as fuel and mention that 'n' nm is 'y' tons of diesel fuel.

OR
       2...with Turboelectric drive....do either of 1A or 1B, but add misc wt for the +25% wt of Turbo-electric.

OR
       3... we assume each ship is built with an aux generator.   Not my choice, but figured I should toss it out there.
Lots of ships were not fitted that way, and if we're paying for extra pumps/fire ext/ NF and other stuff I think should be part of standard fittings, then something like an Aux power plant that wasn't a standard fitting should be called out.

Regarding Mixed Drive I think that should be done with #2, specifying a diesel for 1 or 2 shafts and steam for the others. That is going to take some notations.
     

[TacCovert4]

I think that the simplest solution is to note a misc tonnage below water as 'Auxiliary Generator'.  If it is an auxiliary, I think you can skip noting the fuel for it as a tonnage, as if you need the generator you're in a situation where you don't care about a little bit of range.

[The Rock Doctor]

I think it'd be easier to assume it's just part of the ship's fittings, and if one wants "extra", like with pumps/fire hoses, then sure, pay for it.  But then there's a question of just how much is needed.  There's a lot less stuff using electricity in a 1930 ship than a modern ship.

[The Rock Doctor]

I see that the North Carolina class had two 200 kw emergency generators to back up its normal powerplant, so that's probably a high-end figure for anything we're building now.

[Kaiser Kirk]

Hmm,
To me the utility is if you want to provide for ship power while under surprise attack.
Which becomes more relevant as more electric power is needed, but electric power for turret rotation
shows up as early as HMS Invincible...it didn't work, like really really bad and had to be gutted and replaced... but...

Without a fair amount of digging, I really wouldn't tell which ships / ship classes normally had it, or how much was needed.

Well SS is 42t for 1000kw... or about 25kw/ton
North Cara was under 40k tons (37 standard) and had 2x200kw according to Rocky.
I do have a vague notion the US was lavish with electrical as well.

We could make a kludge Misc Wt of
"if you want an Aux Gen, it will take 1kw per 1000 tons, at 25kt / ton.".. or somesuch.

[TacCovert4]

WWII USN was extremely lavish with electrical power.  Of course all the auxiliary generation came in handy when the main engines got knocked out on numerous ships, so it's as much a DC function as it is a 'surprise attack' function.

I think that within the bounds of the existing engine techs we can consider that SS reasonably sims enough power generation to keep basic shipboard functions going pierside when the main engines are off.  I would say that if you want enough power to truly run the ship sans boilers/primary diesels, you'd need to add it as Misc weight, but if you're only interested in being able to run the lights, ventilation, bilge pumps, and some odds and ends, then that sort of capacity already exists in the SS engine tonnage.

[Kaiser Kirk]

Well in 1910 I figured I'd kick off by a manufactured war and a harbor strike on Aden.
Meanwhile I was concerned about Salahal being so close and not well defended from sea approach,
so harbor strikes have been on Parthia's mind for a long time.

As I add more pumps and electrical aspects, I suppose I should consider the DC side as well.

Either way, now that I have Diesels, I want them on my vessels.

Optimally I'd like them as something that could move the ship at ~6knts and get underway
while the steam plant works up...but I think that's only doable under Diesel-Electric drive.

I'm happy to 'pay' under either a smidge more engines and fuel bunkerage,
or Misc weight.

Sounds like the consensus is ...
Misc Weight.

We can use the main engines KW to figure out how much power X tons of misc wt 'buys'. Then allocate a tiny bit of tonnage for fuel.
All and all about 15-20 tons looks to be a reasonable total.

[TacCovert4]

Germans regularly used a single diesel shaft for cruising with two steam shafts for combat. 

Maybe run diesels for the portion of tonnage needed for cruising speed.....and the rest of the powerplant is steam?

[Kaiser Kirk]

Hmm.
That could be doable.

I have a 1926 ... 30knot 57,500t design and SS gives the to much power per shaft at 2 props but not at 3.

It also does not get upset if I specify 5 propellers.

Ironically that series the lower speed designs are already electric drive, so I just added .1 knot and called out in notes what it meant.