Gas fuelled ships, 1963 style
MAN's gas-fuelled four-stroke on test in Augsburg
One of ‘The Motor Ship’s’ campaigns was to promote the advantages of the Diesel engine over steam power. Therefore it was rather a surprise to read in the July 1963 issue a leading article on a ship powered by a steam turbine.
The ship in question was the Methane Princess, the first purpose-built ship for carrying liquefied methane, today more commonly called LNG. Her design closely followed the Methane Pioneer, a converted US-built tanker. She was the first of two sister ships built for the transport of natural gas from Algeria to the UK. The article drew attention to the ships’ Foster-Wheeler boilers, intended to burn either liquid fuel or boil-off gas from the cargo tanks. The article concluded: “Dual fuel systems of this type are not, of course, confined to steam-raising plant and it is well known that some of the leading marine diesel engineering companies are developing main propulsion diesel engines for gas/ heavy fuel operation.”
The July 1963 issue went on to describe this ship in more detail, as well as another way of using the product carried in the tanks for propulsion – namely tests on a Sulzer 6RD68 two-stroke engine running on crude oil. Surprisingly little difference between HFO and crude operation was noted, though the article did take a cautious view on possible effects on liner wear and other maintenance aspects. Sulzer engines, now part of Wärtsilä of course, were to become well accustomed to running on low-grade oils over the following half-century. Wärtsilä, then, was a comparatively new engine company, having built its first marine engine at Vasa in 1960. The company had delivered around 120 engines to coasters, ferries and icebreakers which were too small to appear in The Motor Ship’s statistics, which concentrated on ships over 2,000dwt. But July 1963 saw the debut of a 240mm bore engine that, in turbocharged form, would develop in excess of 1,000bhp.
The main focus in July 1963, however, was the novel idea of remotely controlling ships’ machinery from the bridge. Two systems were described in considerable depth: a Stephen-Westinghouse pneumatic system, the first on a British-built and British-owned ship, the 10,630dwt Mahout, for Brocklebank’s liner trades; and a German system demonstrated in Augsburg by MAN and AEG. This was an electro-hydraulic system which could be applied to any KZ-series MAN engine.
In the August 1963 issue the story continued, with a simplified pneumatic system developed by Sulzer as part of a project to re-engine a pair of French cargo liners with 6RD68 engines. But the real look into the future referred to the dual-fuel concept mentioned the previous month. A long article described in detail MAN’s development of dual-fuel diesel-type engines as propulsion plants for LNG tankers.
In this case, ‘dual fuel’ means that rather than the current vogue for running on either gas or liquid fuel, the engine burns gas with the addition of 8% to 10% diesel oil as a pilot fuel, although it is capable of running on 100% diesel fuel. MAN noted that gas-fuelled ships were not new even in 1963. Even pre-1945 some German river ships were fuelled by ‘producer gas’, gasified onboard from coal stored in the ship’s bunkers.
MAN’s GV52/74Am.A four-stroke engine had been used as conventionally-fuelled main propulsion engines at sea, as well as in stationary applications on land in dual-fuel mode. The article looked at using the dual-fuel version for ship propulsion, and saw this as being perfectly feasible. The major potential difficulty was that the engine characteristics and propeller curve were considerably different when running on dual fuel from running on diesel only, but with appropriate fuel regulation, which could be achieved partly automatically, this could be overcome.