Ralph Munro’s Reminiscences – Part 2 – Coral Dredging

At this stage I joined Queensland Cement who were working from Ormiston and dredging coral from Raby Bay. We had our own private island, which we accessed via a causeway from the road next to the little church just down, from Ormiston House. The island was formed from ironstone that was pumped up while they were dredging. We closed it down for years but when they built the Gateway Bridge, we opened it up again. All the coral sent up river to make the cement used in the Gateway Bridge came from Raby Bay. We kept the dredging going for five years to get the stockpile up to build the gateway bridge. We put the old dredge Kawana into use for two years while the new dredge Amity was being built. The loading barge for it was the John Oxley, which could carry three and a half thousand tons. 

Coral Dredge in Raby Bay (photo courtesy Ralph Munro)

The Kawana was a suction dredge and had been used to cut channels and pump the sand up to raise the land level at Kawana Waters Estate. At Raby Bay there was a floating line out to the loader barge so that we could put a barge under either side, and get about 1200 tons in each. The sucker-cutter would work side to side pumping the coral back in through a 16-inch pipe. There were five 16-inch pipes on each side of the loader barge. 

We used the tide to help the tug take the barges upstream. By dredging at low tide, the tug would get the tide helping all the way up the Brisbane River to Darra and on the outgoing tide she would take the empty barge back to Raby Bay. Over the period of 5 to 7 years of the dredging that would save well over $1 million in fuel. The tug was the Moreton Tug and Lighters pusher, then later when we built the new dredge for Mud Island and St Helena it was the John Oxley, a giant split barge that was self-propelled. When it got up to Darra, the bottom opened and it dropped the load of coral into a clay hole and then it was grab loaded onto a conveyor belt into the kilns where it was crushed and burnt to form the lime that makes the Portland cement, the strongest engineering cement. The Gateway is made from the strongest engineering cement in the world. 

After coral dredging finished at Raby Bay, we went to Mud Island and St Helena. The prisoners at St Helena, of course, were the first to use the coral from the island in the kiln that still is to be seen on the island. The wash up coral travels up through the island and destroys the vegetation. It is very light and at Raby Bay at low tide you can see it washing towards the beach. 

I had gone back to yacht sailing by this stage, and was able to use my weekday dredging to benefit my yacht racing at the weekend. I was able to dig away at the coral on the Eastern side of St Helena to my benefit in yacht races because our vessel would know where to cut corners and thus give us an advantage. On Monday there might have been 2 feet at low tide but by Friday there might have been 38 feet. We could go down through the coral until we reached ironstone and then we would have to stop because we couldn’t have more than 4% ironstone otherwise it wouldn’t go through the kiln properly. On some spots off St   Helena we went down 65 feet. As we dredged closer into the island, we had to keep lifting our cutter when we hit ironstone. 

Coral dredging got traded off for a section of Mount Etna in Central Queensland but I think that too is now exhausted and Queensland Cement bought a new ship the Warden Point which goes to Whyalla to get the fly ash (90% pure lime) and to New Zealand on alternate trips to bring the lime to our Darra Cement works. 

My last job with Queensland Cement was the clean-up of the buildings at Southbank after the finish of Expo 1988. To save 2000 to 5000 truckloads of rubble from rebuilding the Expo site passing through the city, I suggested to Chris Sorrensen that we hire out our barges to Expo and take the material to the designated dump ground on the inside of Mud Island. This we did. 

After that I worked at the Prawn Farm and then ran a boat for Kerry Bell who owned Queensland Fasteners. The boat was a 52 footer and was called the Lady Bell. It was my job to take customers on Night River cruises, two or three times a week. Or weekend fishing parties. Kerry was building the company to make it more attractive for a takeover, and succeeded. This went on for three years until my mum got crook, so I came home. 

I was keen to get into houseboats in the NSW Northern Rivers, but the NSW Government banned live-aboard boats. (Living aboard was limited to 10 nights every 6 months unless it was a charter boat). I am still exploring the rivers there and a houseboat would have been the ideal way to do it. 

Coral Dredge cutting gear (photo courtesy Ralph Munro)

Ralph Munro 12 January 2008 

(Extract from Peter Ludlow’s book ‘Moreton Bay People 2012’ (now out of print)