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Northern Star. Voyages 2, 3 and 4 continued.
The publicity given to the Thrust Bearing failures on V1 had the effect of drawing attention away from problems with the Boilers. These started very early on. Shortly after leaving Southampton on V2, a hole developed in one of the superheater tubes. It was probably just an isolated material defect, not linked to subsequent superheater problems. However, it stays in my mind because of the temporary fix carried out at Las Palmas. Doc Lovatt was anxious to get on with the job of plugging off the defective tube in the short time available in port. One of the burners was removed and a couple of timber planks were thrown into the combustion chamber, to give some degree of insulation from the heat still being given off by the furnace floor.
Doc was just in the act of climbing into the furnace when the timbers burst into flames! He made a swift exit and waited a couple of hours before going back in to finish the job. Little consideration was given to personal health and safety in 1962, but this incident illustrates the dedication and effort the Engineering Staff put into their ships. Was this appreciated in Leadenhall Street? I doubt it. “Bloody Engineers made the ship late again.”
The main problem that affected the Boilers, at least during the first 4 voyages, but probably for the ship’s entire life, was the build up of clinker on and around the superheater tubes. The correct engineering term for this condition is “slagging,” and Northern Star had slag in spades!
The main cause was a design fault with the Babcock Boilers. The superheater tubes were pitched too close to each other, allowing the slag to build up on the tubes and then bridge the small gap across to the adjacent tubes. The whole superheater became blocked which resulted in a low superheat temperature, eventually we operated at about 800F instead of the design 900F. This was a high figure for a marine boiler of the time, the design temperature on Southern Cross was only 800F. Ironically, had the design temperature been 800F, the tubes could have been more widely spaced and the bridging and blocking would not have occurred to the extent it did. Had the boilers also been fitted with steam instead of air blowers, the whole installation would probably have operated with a lot less trouble.
Could the ship perhaps have enjoyed as long a life as her illustrious sister? Who can tell, but it is a great shame that Northern Star was scrapped as early as 1975. Essentially a straightforward and well thought out development from Southern Cross, it was indeed unlucky that a few minor design details blighted the operation and reputation of Northern Star. It would be interesting to hear about the machinery problems that persisted after the first four voyages.
It was not just the machinery that caused problems in Northern Star’s first year. Remember, the ship started its seagoing life by leaving the Tyne stern first. But it ended the first year by making a very fast homeward passage on V4. This was because the ship spent an extra 2 days at Wellington having temporary repairs made to a long gash (50ft?) in the side plating just above the water line. The gash was caused while berthing during a gale.
Dick Goodey
9th February 2012
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