Thursday, 17 September 2015

EMPTY BALLAST TANKS.

The Mercury (Hobart) Friday 13 January, 1911
LONDON January 12
Captain Bidwell  said he was unableto explain why the ballast tanks werefull on the first voyage and were leftempty on the second homeward trip toDurban.
It is absurd that Captain Bidwell, the marine superintendent for the Blue Anchor Line, was unable to explain this. The Waratah was their flagship, having completed only two major voyages in service. This should have been a red flag moment at the Inquiry......
Captain Bidwell could have explained that the differential in cargo volume and weight accounted for ballast tanks that were either full or empty. The Waratah, as was discovered on the maiden voyage, needed significant dead weight as low down as possible to enhance stability. If the cargo component was limited, it required the filling of ballast tanks (1 338 additional tons).
The fact that the Waratah on her return voyage, via Durban, did not require the filling of ballast tanks suggests that the cargo component and lead was significant enough for dead weight ballasting and air in the ballast tanks provided important residual buoyancy.
Why did Captain Bidwell simply not say so??
If the statement '9 000 tons of cargo' is true (see previous post), combined with 1000 tons of lead concentrates (used for ballast) we get the widely quoted total of 10 000 tons. Mrs. Hay, a passenger on the last voyage, referred to 10 000 tons burthen, which is a Builder's Old Measurement for estimated cargo tonnage. 
As it turns out there were probably at least 360 tons of ballast water in Waratah when she departed Durban.








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