[Vehicles] Marine Steam Engines

Marasmusine · 01-18-2023, 05:51 AM

Hello all, time for my annual Vehicle-related post.

This time I'm looking at marine steam engines. It seems to me that their power-to-weight ratio is much lower than those used for locomotives.

For example, the RMS Titanic's multi-expansion steam engines produced a total of 22,000 kW with a weight of 5,890 tons.
(calculated: 2 engines, 720 tons per engine, 195 tons for each engine bedplate; 29 boilers at 91 tons each, each with 48.5 tons of water - this doesn't include the weight of the steam turbine.)
So about 4 kW per ton.

My estimate for a LNER Class A4 locomotive engine is 75 tons (75-percent of the weight of the vehicle), generating 3,000 to 4,000 kW
So about 40 to 50 kW per ton (this is also about the power-to-weight given for a "triple-expansion steam engine" in GURPS Vehicles).

I wonder why the marine engine has less power-to-weight by an order of magnitude. More fuel efficient? Cheaper per ton?

01-18-2023, 05:51 AM	#1
Marasmusine Join Date: Feb 2005 Location: Doncaster, UK	[Vehicles] Marine Steam Engines Hello all, time for my annual Vehicle-related post. This time I'm looking at marine steam engines. It seems to me that their power-to-weight ratio is much lower than those used for locomotives. For example, the RMS Titanic's multi-expansion steam engines produced a total of 22,000 kW with a weight of 5,890 tons. (calculated: 2 engines, 720 tons per engine, 195 tons for each engine bedplate; 29 boilers at 91 tons each, each with 48.5 tons of water - this doesn't include the weight of the steam turbine.) So about 4 kW per ton. My estimate for a LNER Class A4 locomotive engine is 75 tons (75-percent of the weight of the vehicle), generating 3,000 to 4,000 kW So about 40 to 50 kW per ton (this is also about the power-to-weight given for a "triple-expansion steam engine" in GURPS Vehicles). I wonder why the marine engine has less power-to-weight by an order of magnitude. More fuel efficient? Cheaper per ton?