Coal to Oil fired boilers

[Historiker]

When a ship's boilers are changed from coal fired to oil fired, what impact has that?
1. Does it get faster? I don' know one case where this happend.
2. What about the amount of fuel it can carry? How many tons of Oil can be carried for how many tons of coal? Oil is liquid, so it uses all the space, while it has a significant lower weight.
3. What about the range? It gets bigger, but by which ratio?

[herwin]

ORIGINAL: Historiker

When a ship's boilers are changed from coal fired to oil fired, what impact has that?
1. Does it get faster? I don' know one case where this happend.
2. What about the amount of fuel it can carry? How many tons of Oil can be carried for how many tons of coal? Oil is liquid, so it uses all the space, while it has a significant lower weight.
3. What about the range? It gets bigger, but by which ratio?

Oil fuel has a higher specific heat content (energy per ton), so you get a speed and range boost.

[Historiker]

Yes, I know. But I haven't seen any data yet, that showed a speed boost.
Do you have any data that shows how much the stored fuel changed - and how much the range?

[herwin]

ORIGINAL: Historiker

Yes, I know. But I haven't seen any data yet, that showed a speed boost.
Do you have any data that shows how much the stored fuel changed - and how much the range?

You would need to do some web research. I don't have anything directly at hand.

[Historiker]

Hmm
Bituminous coal has a SKE of 1,016; Petroleum has one of 1,428; Gasoline one of 1,486 - so for the used oil, I guess it will be in between, let's say 1,450.

coal has 1.350 kg/m³; petroleum between 750 and 1000kg/m³, so I take 1000 to allow easier calculation and to mention the air between the coal.

So if a ship has 3000t of coal onboard, that means it has 2222 m³ for coal. So 2222t of oil can be carried instead.
3000t of coal have 3048k SKE; oil will have 3222k SKE
That would mean less than 10% increased range...

Hmm. How much % of a filled coal bunker will be filled with air (between the chunks)? 10%? 20%?

[el cid again]

It is complicated and technical - and you need the exact data about what is done. Coal and oil are not stored the same way - the ship needs to be rebuilt - and you need to know what is done exactly. But there are cases where the power went up, the speed went up, and the range went up. There are also intermediate cases: oil sprayed coal for example, and dual coal-oil fired boilers (both were fairly common). Then there is the nature of the new plant: is it steam?? If so - reciprocating or turbine - or steam electric? Is it diesel? It can even be diesel electric.

In general - do not change engines - or change them to historical sets - so you have good data to work with.

[Historiker]

Well, you know my problem...
I have a number of old ships that were scrapped or sunk IRL, so there is no data. I don't want to get totally fictional by letting everyone of them undergo a radical modernization like the Japanese BBs. Equiping them all - especially as they are still old ships - with modern engines makes no sense, so a reconstruction of the existing engines from coal to oil would be most likely.
As many old ships have very limited range, this should happen - but it should happen in a way that makes sense. For that, I need some kind of formula like showed above to find out what can be done...

[el cid again]

Read Schlachtshiffe und Schlachtkreuzer - look up Goben - and old British battleships - notably the case that served until 1944 - Centurion. Lots of details there.