Wärtsilä 31SG

The Wärtsilä 31SG is a 4-stroke pure gas (spark gas) marine engine. It ignites gas with a spark plug instead of liquid pilot fuel, so it runs on gas only and needs no back-up diesel fuel system. It is intended for vessels operating with a secured gas supply, for example on fixed short routes with gas bunkering infrastructure.

Technical data

• Configurations: 8 to 16 cylinders
• Power output: 4.2–8.8 MW
• Speed: 720 and 750 rpm
• Emissions: meets IMO Tier III

Key features

• Low fuel consumption over a wide operating range
• Full output for a broad range of gas qualities; well suited to gases with a low methane number
• Modular design reducing maintenance time and costs
• Offered as an additional option alongside dual-fuel Wärtsilä 31 versions

Hybrid operation

In a hybrid engine-battery configuration, reduced running hours can save 5–20% in maintenance cost, with typical additional fuel and emissions savings of 2–6% on top of the switch to SG technology. Class redundancy requirements for gas-fuelled single-fuel vessels (typically back-up power of min. 40% of MCR) can be met with a redundant gas supply system and a multi-engine configuration.

Applications

Diesel-electric configurations or auxiliary engine use on a broad range of ship types, including FSRUs, LNG carriers and ferries.