Jun 27 2007
The recent stranding of the Pasha Bulker on Nobby's Beach at Newcastle brings fresh interest to a unique method of marine salvage whose principles were first published over twenty years ago by Civil Engineering's Ian Bowie.
Building on Bowie's idea, University of Sydney Honorary Associate Professor Rob Wheen, former Head of Civil Engineering has last week added a further practical step that makes the idea immediately relevant and offers the prospect of recovering the vessel with surprisingly small effort and at minimal cost.
The two inventors are so convinced of the novelty and efficacy of their method that they lodged a patent application last week entitled "A method of salvage for vessels stranded on porous media of low permeability". The sandy beach at Nobby's Head is a 'porous medium of low permeability'.
The salvage details will vary with each stranding but the essence of the method is to pump seawater into the sand immediately below the hull of the vessel. The effect is to partially fluidise the sand creating a condition that, at its extreme, would be known as the quicksand beloved of the creators of Tarzan movies.
'Pumping seawater under pressure into the sand has the effect, in simple terms, of reducing the friction between the sand grains and between the sand and the hull so the tractive effort to remove the vessel is very much reduced. It is conceivable that the vessel could drive itself off using its own propellers,' said Professor Wheen.
Successful experiments were conducted by Mr Bowie with the assistance of undergraduate thesis students on Dee Why beach in the early stages of the development of the idea. The method could easily be demonstrated afresh with minimal effort.