Project Officer for the Bureau of Meteorology…………A job I was proud of
The automatic weather stations proposed for the Bureau of Meteorology required a project officer, who was normally an architect, but these had no architectural content and were basically structural as for Cooby Creek Satellite Tracking Station, I ended up with the job.
The supervising architect had arranged an inspection trip by charter vessel from Brisbane to Townsville to look at coral cays for this program. The aim was to eventually have a chain of these automatic weather stations on the outer fringes of the reef to transmit weather data for cyclone warning. There was only a manned station at Willis Island and the landfall lighthouses were relying on transmissions from vessels in the area for the basic forecasting data. To fill in the gaps it was planned to construct remote automatic stations on coral cays near, or on, the outer fringe of the reef, as well as incorporating automatic stations on light-house towers proposed along the coast for landfall lights. These included Fredrick Reef, Euston Reef and Saumerez Reef. Unlike Cato Island, which was a well-established island, the coral cays were just that, coral sand built up on a coral rock-base possibly three metres about high tide at the best, but wind and wave-swept so that the loose coral sand moved with the seasons.->
The Supervising Architect requested an Engineer accompany him on the trip north and I was nominated. The Rigel Kent was a timber carvel hull launch about 45 foot long with Gardiner diesel engines, automatic pilot and radar. It was a vessel anyone would be proud to own and the owner was Peter Barnes, the brother of Beverley was at school with me and married to a Patrol Officer in Papua New Guinea…a small world. Peter was the skipper and had a friend of his as deck-hand, then there was Stuart and myself. Stuart was concerned that I might get sea-sick as the trip was on the outer fringe of the reef from Brisbane to Townsville. We boarded the Rigel Kent at a private jetty at Bulimba in the Brisbane River and I said my farewells to Betty, Oscar and Rebecca; we cast off and headed to the mouth of the river then north towards Frederick Reef. Peter set the routine for the ship, meals, happy hour and night watches. That first night all was well except Stuart was sea-sick from the roll of the vessel. This was surprising since he had just returned from a long cruise by ocean liner. Anyway it ended up with him sipping lemonade and sucking ice-cubes while the three of us enjoyed the meals and a couple of cold beers in the evening. Stuart decided we should proceed and not cancel the trip, but he was not enjoying it during those first few days.
Frederick Reef was the first stop about 400 nautical miles north of Brisbane and approximately 300 nautical miles east of Mackay. This was to be the site for a one hundred foot high lighthouse tower incorporating solar powered light and automatic weather station made more important with the development of Gladstone Harbour as a coal exporting port to Japan. I was given the job for design of the tower so it was desirable to see the site and materials available. Stuart’s sea sickness had eased and vanished once we went ashore. The cay selected was elongated with the highest point about eight foot above high tide. There was no vegetation indicating the cay was over-swept by waves after they had broken on the reef edge in heavy weather. The base rock was typical of these cays, solid, massive, but subject to cave-ins. Overlaying this sound rock was fragmented coral rock, then rounded coral rock of varying diameters down to coral sand. The site of the tower was selected and a star- picket driven to mark the approximate centre of the tower. There was a good anchorage for vessels such as the Cape Moreton nearby so landing of construction equipment using the amphibious LARC could be conducted in sheltered water.
Next stop was Marion Reef, approximately 170 miles to N.W. and about 220 miles east of Bowen. Marion Reef was to be the site for an automatic weather station and a similar investigation was made and another star-picket placed to mark the site.
Lihou Reef was also visited and marked for an automatic weather station and we then headed for Townsville through Flinders Passage, disembarking in Townsville and returning to Brisbane biplane. The Rigel Kent then returned to its home port.
So I was back home again with the family. Fortunately there were no disasters while I was away. The children were doing well with their art and Rebecca was singing in the occasional eisteddfod and doing a good job, but there was not much enthusiasm shown with the piano, but we kept up the Saturday lessons.
In the office I was kept busy and doing the work I enjoyed. Frederick Reef Lighthouse was a tubular stainless steel structure 100 feet high free standing. It was based on a tubular guyed structure built on New Year Island in the Northern Territory for which wind tunnel tests had been done giving more accurate information on wind shedding and coefficients than the Australian Standards gave. It showed that by providing slots in the tower vortex shedding characteristics were changed for the better. The Swiss Wind Code was more advanced than ours and its coefficients were used for calculating the wind load on the tower. Those coefficients were important for calculating the applied load since deflection at the top had to be limited in order that the focal plane of the light was not bouncing everywhere. The shape of the tower was determined by the needs of its functioning effectively. The focal plane of the light had to be at least 100 feet above sea level and access all around the light for servicing and supports for transmission aerials and solar panels. Access was to be within the tower by ladder. Provision was to be made for: (i) shelter for seamen should they be wrecked on the reef. (ii) Equipment for automatic weather station with batteries and solar panels and transmitting equipment. (iii) Equipment for automatic light, batteries, solar panels, aerials and automatic rotary switching when a bulb blows. (iv) Security of equipment from vandalism. (v) Protection of equipment from weather. (vi) Insulation of equipment rooms to keep the temperature down to permit staff to work on the equipment and not ‘cook’ the equipment. (vii) Keep tower segments to a size that could be shipped and unloaded on the island and be erected without a mobile crane.
The resulting tower ended up with cylindrical units fabricated from Grade 316 stainless steel. The rolled sheet was butt welded to form the cylinder and welded to a flange ring internally each end. Floors were welded in place with man holes for access and ladders. The objective was to bolt the cylinders together keeping the joints under compression for wind loads and tensioned stainless steel bolts were used for all joints. The flange rings were gusseted each side of a bolt. In total the tower ended up with five cylinders approximately 10 foot diameter by 8 foot high, then one cone segment tapering from 10 foot diameter to 3 foot diameter by 12 foot high, then four 3 foot diameter by 12 foot high. There was a balcony at the top all round and another below the taper cone segment with access doors. These had to be designed such that they could be erected from inside the tower by securing to a flange ring and working your way around bolting steel grating in place as you proceeded. The stainless steel shell of the tower got hot during the day and vents were built in the walls of the large diameter sections. There were designed to admit and exhaust air and keep water out. The small diameter segments were vented through the vortex shedding slots and drainage holes provided at the bulkhead. Framing was welded into each segment to suit equipment and insulation installed where needed. That basically was the design for the tower. Then came the foundations to resist wave action and wind loads. The wind load was based on 120 mph winds. The wave load was calculated from maximum wave height over-tipping the cay. There was an unlimited fetch from the East from which direction a wave could come with water depth over 1000 fathoms and the wind generated wave hits this almost vertical wall of coral, breaks and surges across the lagoon and over the cay. There were numerous reports and theories and I settled on the findings in the American Society of Civil Engineer Journal which recorded wave situations similar to this in Hawaii and Japan; finding the maximum wave height recorded surging across the lagoon was eight feet, this was adopted. The resulting footing ended up a circular pad about 25 foot diameter long, 4 foot deep, set on the firm coral base into which steel pile section I beams were driven to refusal as a safe-guard against the base being undermined. Some piles went down nearly 20 feet and it was not uncommon for a pile to drop as it went through a cavern. Stainless steel reinforcing was used and the coral rock and sand used for aggregate along with sea water for the concrete mix. On top of this circular base a mass concrete square plinth about 12 foot square and 6 foot high was similarly reinforced and tied into the circular base to form a large pad for the tower base and to accommodate the stainless steel anchor bolts for the tower base. Contract documents called for a trial erection before delivery and this was done by assembling the units on their side. The tower was fabricated at Rochedale near Brisbane and its erection organised by the Construction Section of the Department. The Cape Moreton was used for this phase. That was a job I was proud of.
After this came Marion Reef Automatic Weather Station, basically a stainless steel pipe framework supporting a box-like shed approximately 10 feet above the cay. The building was about 12 foot square by 10 foot high sheeted with stainless steel Kliplock panels. There was a balcony for access and the roof was decked and surrounded with a handrail and the instruments were mounted on the deck. Being built at the top of the cay the footings consisted of four steel piles with a concrete ring beam over them. The piles were driven to refusal and as the seasons changed the cay moved back and forward exposing the concrete beam and piles and building up again next season. The coral rock base was as stable as could be expected but the coral sand build up to form the cay moved with the seasons, affected by wind and wave action.