Friday, 4 October 2013

PORT NATAL SANDBAR.

Could the Waratah have struck the sand bar at Durban Port? From the previous post it is clear that there was very little visibly wrong with the Waratah when she left Durban Port. The sandbar at the entrance of Durban Port needed daily dredging to create a channel deep enough for steamers as large as the Waratah to enter or exit. 

I believe, as I have outlined previously, that the Waratah had latent defects in the form of weakened hull plates and rivets due to the damaging forces when she ran aground at Kangaroo Island in December 1908 and taking the ground at Port Adelaide prior to departing for South Africa. These defects may not have been visible to the naked eye and further compromised when she was dry docked after her maiden voyage. Hypothetically the Waratah may have scraped the sandbar on her exit from the Port at Durban. As in the case of the Titanic a scrape against the iceberg caused compromised rivets and plates to open up gashes in a zipper like effect.

Durban Port is sheltered as one can clearly see from the map on the previous post. However, part of this protection is the sandbar at the mouth of the Port which forms every day due to the opposing currents to the southerly Mozambique current, create a littoral drift of sand curling around the Bluff. This sandbar in the days before dredging made it impossible for average ocean going vessels to enter the bay, forcing them to anchor at sea and ferry both cargo and passengers to and from the Port.

Charles Crofts was appointed harbour engineer in 1895, and was the first to officially start using dredgers capable of working in the open sea. His predecessor Methven had ordered a trailing suction dredger called the Octopus, which could tackle the silt build up of the sand bar on a daily basis. The daily dredging of the sandbar eventually allowed large vessels to enter the harbour, notably the 12 967 ton Armadale Castle in 1904. (The Armadale Castle had a very similar draught to that of Waratah, when she departed Durban)The stage was set for an ongoing battle with the sandbar addressed daily by dredging bringing the all important benefits of access to the harbour by larger vessels. 

It is not a flight of fancy that the Waratah, being almost fully loaded and therefore low in the water, could have scraped the sand bar on exiting the Port. This may have only resulted in a minor jolt considered insignificant and not important enough to report or return the Waratah to her berth for inspection. It is conceivable that the Waratah sustained further damage to rivets and plates much like the straw that broke the camel's back. All that would then have been required was a rough sea (tick) and the various forces as discussed previously applied to the weakened hull plates. The Waratah's death knell may possibly have come in the form of Durban harbour's notorious sand bar?

In reality I doubt whether Waratah touched the sandbar exiting Port Natal, 26 July.


the narrow mouth Durban harbour clearly seen in this image - requires constant dredging


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