Diesel benefits underlined

01 May 2014
The Hall Russell built ‘Hebrides’, for Scottish Western Isles services

The Hall Russell built ‘Hebrides’, for Scottish Western Isles services

Such is the dominance of the internal combustion engine in today’s ships that it is easy to forget that the prime purpose of ‘The Motor Ship’ when launched in 1920 was to promote the advantages of the Diesel engine over steam power.

Many years on in our journal’s existence, in fact exactly 50 years ago in the May 1964 issue, The Motor Ship’s editorial team was pleased to point out that the last major market for the steam turbine – the US – was about to succumb to Diesel superiority. They went as far as to say that many US naval architects were out of touch with reality, though they did say this was understandable because the high-power Diesel had up to then played no part in US shipping. Several studies had been undertaken to convince US administrators, owners and designers that the modern diesel engine was a much better option.

It was acknowledged that US flag operation incurred high overheads and manning costs, which tended to diminish the importance of fuel economy. Although, interestingly, it was suggested that the problems of US operators would be those faced by European and Far East owners in the near future. But one of the studies proved that although a Diesel installation represented a 115t increase in lightship weight compared with a steam turbine powered typical cargo vessel, the fuel savings with Diesel power equated to a significant improvement in cargo deadweight for any run of 2,500 nautical miles or more. Although maintenance costs for a diesel plant are higher, this was more than offset by the savings in fuel cost and the lower manning levels. And as automation took hold, manning costs could be reduced still further.

Two other headlines from 50 years ago caught our eye. One warned of false economies in lubrication, pointing out that not all alkaline cylinder and crankcase oils are the same, and the trend for saving money by choosing the cheapest option when operating with heavy fuel was not likely to pay off if corrosive acids intrude into the oil, and cylinder liner life is halved. As we have noted before, cold corrosion is not necessarily a new phenomenon. And another proved interesting in the light of slow steaming trends. A recent technical paper had suggested that operating engines at reduced output – even 10% below normal continuous rating – had a detrimental effect on engine performance, with fouled turbochargers, broken piston rings, and shortened lubricant life. So fuel savings, usually on charterers’ instructions, were more than offset by the cost of repairs and going off-hire.

Among the new ships described were an LPG tanker, built at Meyer in Germany for a Norwegian owner and on charter to a French operator. The 67.7m ship had tanks for about 1,400m³ of propane, and was powered by a medium speed Mirrlees engine of 1,440bhp. And interestingly, as this issue features a Scottish ferry, the May 1964 issue had a detailed description of a new class of ship for the MacBrayne Western Isles services. The 235ft (71.6m) Hebrides was designed to carry 600 passengers, as well as 50 vehicles loaded in a garage on the main deck via turntables with hinged ramps on each side. The loading ramps were protected by sliding watertight doors, supplied by MacGregor. Two 8-cylinder 1,200bhp Crossley engines were chosen for main propulsion due to their low vertical height – even so, the deck had to be raised above the machinery compartment. Oddly, UK government regulations specified decontamination chambers, air locks and sprinkler systems in case of nuclear fall-out being encountered.