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The Rocky Bay Canal Proposal
For most of the 19th century, a ship canal through the narrow strip of land between Rocky Bay and the ocean was put forward as a way to give large ships direct access to the Swan River. Vessels would enter the river upstream of the rocky bar and shallows at Fremantle, then continue into Melville Water, where they could anchor in sheltered water and unload closer to Perth. The canal was surveyed, costed and debated in Parliament but it was never built.
The first proposals
On 9 November 1837, a newspaper discussing a proposed breakwater in Gage Roads suggested cutting a canal between Rocky Bay and North Beach (Leighton). It was one of two ways the paper thought shipping could be brought closer to Perth. Clearing obstructions at the existing river mouth might let moderate-sized vessels through, while a canal at Rocky Bay could give even the biggest ships access to Melville Water. The article ended with the question of how the colony would pay for the works.
The idea came up again in April 1846 while Captain Twiss of the Royal Engineers was working on plans to defend Fremantle and its anchorage. The newspaper reported that Sir James Stirling considered a canal practicable. It argued that large warships could shelter inside the river, that a gun battery could defend the entrance, and that vessels of 400 tons could get within two miles (3.2 km) of Perth. The paper put the length of the cutting at about 400 yards (366 m) and suggested 600 men could finish it in a year.
By May, the paper was reporting a lower estimate of 300 convicts working for a year, at a cost of about £10,000 for the canal and a breakwater. Twiss thought the bend in the Swan carried the main current away from the proposed entrance, so a narrow opening into the quieter water of Rocky Bay might have little effect on the river. He still cautioned that the new opening could change the currents and cause a bar to form. Rock from the cutting could be used to build the breakwater at the ocean end. The paper wanted Britain to provide the convicts, pay for their upkeep and supply a prison ship to house them. If Britain declined to cover their upkeep, it suggested the colony borrow £10,000 to £15,000.
Taking the proposal to Britain
In April 1847, an editorial suggested making the canal one of the first jobs given to convicts brought to Western Australia for public works. In June, the Advocate-General gave notice that he would ask the Legislative Council to approach the British Government. The request covered the canal and other works the colony could scarcely afford. Britain would be asked to pay all or part of the cost of keeping and guarding the convicts, who would be sent out of the colony when their sentences expired.
When the Council debated the proposal on 23 July, the Advocate-General described a cut about 400 yards (366 m) long and an average of 15 feet (4.6 m) deep, just wide enough for a ship to pass safely. He gave the depth at Rocky Bay as four fathoms (7.3 m), with four to six fathoms (7.3 to 11 m) between Rocky Bay and Point Lewis. He told the Council that Twiss had based his assessment on information from people familiar with the site. The estimate given at the debate was 300 convicts working for ten months, including time to build their quarters and stockades, at a total cost of about £9,000.
The Surveyor-General warned that a second outlet could make the river shallower as far upstream as Point Walter. The Colonial Secretary doubted the canal would succeed and the Governor questioned what it would cost to transport, feed, house and guard the workforce. There were also concerns about how the colony would feed hundreds of extra men when flour was already in short supply. The Council appointed Roe, Leake, Nash and Andrews to draft the address to Britain and seek an engineer’s assessment.
In August, Mr Gregory measured the crossing at 28 chains, or about 563 m, more than half as far again as the 400 yards quoted in July. By October, a newspaper was calling the canal beyond the colony’s means and suggesting a cheaper passage through the existing rocky bar near Rouse’s Head. In November, Lieutenant Helpman was ordered to measure the water depth off the proposed ocean entrance. The committee’s report was still unfinished when the Legislative Council ended its session, so the matter passed to the Executive Council.
slwa_b1802043_1 Sketch Plan of the Mouth of the Swan River Rocky Bay
Henderson’s survey
In May 1850, with convicts due to arrive, the canal was again suggested as one of their first jobs. Newspaper coverage weighed up three options: cut the canal, open the existing river mouth, or build breakwaters to shelter ships in Gage Roads. A harbour in Melville Water would be closer to Perth and offer places where ships could stay afloat while loading and unloading. Getting ships safely through the proposed ocean entrance was still in question.
Comptroller-General Edmund Henderson examined the same three options in his report of 6 November 1854. He put the Rocky Bay crossing at about a third of a mile (540 m). The ground averaged 24 feet (7.3 m) above high water along the route and rose to 34 feet 3 inches (10.4 m) at the Rocky Bay end. Henderson estimated that cutting a canal 24 feet (7.3 m) deep and 150 feet (46 m) wide would take 400 men 600 days, assuming they were cutting through rock. A steam engine would be needed to pump water out of the excavation. If they struck quicksand, some sections could need retaining walls made from closely fitted piles.
Henderson expected the approach from the ocean to be the hardest part. Shallow water extended nearly 200 yards (183 m) off the beach, which was exposed to constant surf. He thought vessels would need steam power to enter even in calm or moderate weather. A breakwater could shelter the approach, but if one could be built there, he questioned whether the canal was worth the extra expense. He also warned that a second outlet could leave both river entrances unusable.
In April 1855, Governor Fitzgerald presented Henderson’s alternative, prepared with help from Captain Wray. It followed the existing river entrance for about two miles (3.2 km) to Rocky Bay, where there was already deep water farther upstream. The proposed channel was 12 feet (3.7 m) deep and was expected to cost £6,600, including £1,800 to blast a passage through the rocky bar. Henderson thought it could allow vessels of about 150 tons to reach Perth. For a harbour that could take ships of all sizes in all weather, he favoured a breakwater off Arthur’s Head.
Test drilling at Rocky Bay
By 1872, the Inquirer and Commercial News was listing the Rocky Bay canal among the harbour plans already put forward. The latest scheme, from Padbury and Randell, would use the existing river mouth. It called for a piled breakwater off Rouse’s Head, blasting through the rocky bar and dredging upstream. The two men believed the works could be carried out for £50,000.
The canal was examined again in 1874. In early June, Mr Leake told the Legislative Council that he was unwilling to guess what it would cost or whether it could be kept clear. Later that month, the Rev. C. Nicolay and a party of prisoners were reported to be boring into the strip of land between Rocky Bay and the ocean to find out what rock a canal would have to pass through.
By 24 July, a Legislative Council select committee had examined Nicolay’s report and plans and heard evidence from the Admiralty Surveyor. The committee declined to recommend the canal and unanimously favoured harbour works in Gage Roads, starting with a jarrah-pile breakwater that could later be filled with stone. Most members favoured a route from Rouse’s Head curving towards Beagle Rock. The committee voted four to three to wait for a marine engineer to inspect the proposed breakwater site.
The last harbour debates
In September 1884, Fremantle member Mr Marmion read Henderson’s objections to the canal back to Parliament. The Melbourne engineer Mr Doyne had agreed with Henderson about the difficulties at Rocky Bay. Doyne thought the existing river mouth might take shallow-draught vessels for part of the year and suggested a railway if more capacity was needed to move goods between Fremantle and Perth.
By June 1886, boreholes, soundings and surveys of the Swan River and Rocky Bay had been sent to Sir John Coode for his report on Fremantle harbour. When his findings were discussed in August 1887, Coode’s objection to the canal was the amount of sand moving along the coast. The entrance would need costly breakwaters, and he doubted that enough water flowed out of the river to keep a deep channel clear. He had much the same concern about the existing river mouth.
Coode’s objections were raised again in January 1892 as Parliament debated C. Y. O’Connor’s plans for the existing river entrance. Coode expected sand to build up against the northern breakwater, round its end and settle across the entrance. He warned that a single gale could undo earlier dredging. His £530,000 estimate was for works at the existing river mouth, with an 18-foot (5.5 m) channel for smaller steamers. O’Connor’s smaller scheme for the river entrance was estimated at £560,000 and allowed for a 30-foot (9.1 m) channel. The Rocky Bay canal was still being cited in the debate more than 50 years after it first appeared in print.
By October 1894, Rocky Bay was back in Parliament over quarry waste being tipped into the river. F. T. Crowder said it was filling in what had been deep water and warned that dredging could cost the colony £100,000. The Fremantle harbour works were already under way and the canal across Rocky Bay remained unbuilt.
