The larger engine becomes reality
The first 850mm-bore Gotaverken engine, a 10-cylinder unit rated at 21,000 bhp, on test at the factory
In its February 1961 issue, 'The Motor Ship' was given over mostly to talk of large-bore, powerful engines.
A couple of ‘comment’ style items included a foretaste of today’s engine. One suggested that the non-turbocharged diesel engine was a thing of the past. This was said with a tinge of regret; but the writer accepted that it was the shipowner who decided on the engine specifications for his ships, and although a few remained reluctant to embrace this relatively new technology the vast majority of engines ordered in 1960 had been of turbocharged design – including almost all of the engines from B&W, which was easily the most popular designer at the time.
Another item revealed that a 36,000 bhp engine could become a reality, following an announcement from Sulzer Bros that the company’s first production 900mm bore engine – although nominally rated at 2,000 bhp/cylinder – had achieved an output equivalent to 3,000 bhp/cylinder at 130 rpm on test bed trials. “One would hesitate to say that today’s maximum will be tomorrow’s nominal service ratings,” wrote the author – but he recognised that a 36,000 bhp 12-cylinder engine had been proven to be within the bounds of metallurgical, design and constructional feasibility.
Other ‘large’ engines, from the likes of Doxford, Gotaverken, Stork-Werkspoor and Kockum-MAN were described in detail, none more so than the ‘future’ Doxford design, known as the ‘P’ type, the subject of a detailed technical paper presented to the Institute of Marine Engineers by Doxford’s R&D manager P. Jackson. The ‘old’ Doxford engine, based on a 1934 design, had a number of shortcomings, not least a tendency to vibrate at higher power levels over 100 rpm, particularly when going astern, which the new engine, still of opposed-piston design, was intended to overcome. The older version did not lend itself particularly well to turbocharging, another feature of the P type. Most importantly, though, the ‘P’ type was designed to be lighter and shorter than its predecessors, and its European competitors of equivalent output.
Following successful trials, the first P type engine had been installed in a tanker in January 1961, the result of which was awaited – not just by the paper’s author, but by a number of other correspondents who had queried certain aspects of the engine design, such as the shorter stroke, the use of lube oil for piston cooling, and the high maximum pressures involved – up to 1,000 lb/in2 was envisaged for the future.
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