[ALARIC]

Northern Star’s Early Life. An Engineer’s view. Part 2.

While the concept and overall design of Southern Cross had been revolutionary, the machinery specification and design were conservative, to limit the overall risks being taken. This was a wise strategy, as the ship proved to be very reliable in service and was still going strong when finally scrapped in 2003.
With the overall principal proven to be correct, the company was more adventurous with the specification of Northern Star’s machinery. With hindsight, it can be seen that in some respects they were too adventurous.
One of the innovations was the new, compact design of boiler feed pumps by G&J Weirs of Cathcart. They had a single, central bearing lubricated by water tapped off the high pressure pump discharge.
Traditional turbo feed pumps had three, oil lubricated bearings. These traditional pumps were very reliable, but big and expensive to make in comparison to the new design. I believe that Northern Star was the first ship to rely entirely on the new pumps. With the space available, there was simply no space for traditional pumps, even if it would have been preferred. There were two main pumps, only one of which was required for full power, plus a smaller Harbour Pump, and this would probably have had capacity to steam the ship at 15 knots on its own. The risk of relying totally on the new pumps was probably considered to be small and acceptable. After Clyde trials, Northern Star anchored at Tail of the Bank, and Weirs sent a team on board, and at least one of the pumps was replaced, as mentioned in part1.
The pumps proved to be problematic to start. Once they were up and running they were OK, but if run up to speed too fast, it was liable to seize because the bearing was running too fast before a proper water lubricating film was established. On the other hand, if it was run up to speed too slowly, it was liable to seize because the bearing was running for too long before a proper water lubricating film was established. The window between what was too fast and too slow was very small, and could only be determined by “feel”. Not surprisingly, a number of pump seizures had occurred, some on V1, but these had occurred singularly, so were not critical to the overall operation of the ship. This all changed outward bound on V2 at Cape Town.
At ports where the ship stayed at the berth only 12 hours or less, a main boiler was maintained under steam and the turbo alternators were kept on load for electric power. At Cape Town, a 24hr port, it was usual for the diesel generators to be run for electric power, with the main boilers and steam systems totally shut down. Your writer was still the Junior Engineer on Doc Lovatt’s 4 to 8 watch, so it fell to me to run up and warm through the machinery for the morning departure. All was going well until I attempted to start the Harbour Pump. I think I tried the fast start, but it was too fast and the pump seized up. Doc was not impressed when I told him, so personally took over the job of getting a main pump running. He tried the slow approach, but was too slow, resulting in two of our three pumps now being u/s. Staff Chief Jack Warden was now called from his bed. I can’t now be sure what approach he tried, and he had probably not ever personally started one of these pumps before, so we soon had a hat trick of dud pumps.
Sailing had to be put back 24 hours. All the Engineers worked 6 on 6 off watches to provide the manpower to strip and repair the three pumps. In the limited space available around the pumps we were virtually working on top of each other, and I was mortified when I hit Jack Warden a mighty blow on his hand with my large hammer. I have always held Jack in the highest regard, having first sailed with him as an Apprentice on Alaric on his first trip as Chief. I think he forgave me, but he never let me forget what pain I had inflicted. Every time we subsequently met he reminded me of how dangerous I was with a big hammer! Indeed, it was mentioned at our very last meeting, at the Southampton Reunion about 10 years ago. Sorry, Jack.
I can’t be sure who was brave enough to start the feed pumps after the repairs, it wasn’t me. The problem was overcome, I think at the end of V2 by simply fitting a small electrically powered pump to provide lubricating water during the start up phase. We live and learn.
Weirs also supplied another significant piece, of what at the time was cutting edge technology. This was a 20 stage Flash Evaporator for making fresh water from the sea. In spite of being a prototype, this equipment really did work well, the water it produced was virtually pure and of the highest quality, and it made 500 tons/day of the stuff. It was so pure that it was virtually tasteless.
In 1962 it is was the largest capacity marine evaporator ever produced, and would still be regarded as big today, although I believe large modern fresh water generators are now of the reverse osmosis type rather than evaporators.
The evaporator was not brought into use until we were well clear of the coast, and it took quite some time to start up and produce good water, but when it settled down, there was no stopping it. There was virtually no control over how much water was produced, it was either the full 500tons/day or nothing! This was well in excess of the quantity normally used for ballast and hotel services, and even in the hottest weather it almost kept pace with demand. Usually, during the 4 to 8 morning watch, all the water tanks were filled, so the evaporator output was dumped onto the engine room tank tops and bilges until demand for water picked up again at breakfast time. On virtually every other steam ship of the time, the most precious substance (apart from beer of course) was good quality feed water for the boilers, and Northern Star used the highest quality water to keep the bilges clean. No ship afloat could compete with that!
The Flash Evaporator was one of the success stories of the advanced machinery, and it gave little trouble during the first year of operation, although I do remember on V2 or V3 there was an occasion when due to some malfunction, the shell and tube heater scaled up and had to be cleared out manually.
In fact, had it been known in advance how well the evaporator performed, the boilers would probably have been fitted with steam soot blowers instead of the compressed air units actually installed.
In my experience, partly because of the higher pressures used, steam soot blowers seem to be more effective than air units. The big disadvantage is the quantity of steam, and hence boiler make-up they need.
On Northern Star, the one problem never experienced was a shortage of feed water. It is ironic that the Boiler troubles which I believe were experienced throughout the life of the ship, could perhaps have been prevented or at least reduced if the ship had been equipped with steam soot blowers.
Dick Goodey