Friday, 13 February 2015

QUADRUPLE EXPANSION ENGINES PROBLEMATIC.

During the course of the Inquiry into the loss of the Waratah, the following witness account was given:

'He gave similar evidence to the other witness about the boat rolling in the Bay of Biscay. The Waratah could not ride heavy seas, and the engines shook the vessel so much that the gear of the aftermast became loosened.' 

Apart from the references to the Waratah 'rolling' and not being able to 'ride heavy seas', the engines allegedly vibrated to an extent that the 'gear of the after mast became loosened'. This phenomenon could also explain why a bolt from one of the upper decks came loose hitting the cook in the galley below; gaps appeared in the superstructure and a steel ladder spanning three decks snapped in two during a calm spell at sea.

Previously I believed short-comings in the construction of the Waratah might have resulted in the above, but excessively vibrating twin engines might actually have been the cause. The Waratah was fitted with quadruple expansion steam engines. At the time this was thought to be an improvement on the successful predecessor, the triple expansion steam engine. As it turned out, the full potential of quadruple expansion engines could never be achieved due to inadequate steam pressure provided by boilers of the time. The enormous weights in quadruple expansion engines, reciprocating at high speed, imposed severe stresses on all parts, including the ship's hull. Under full steam the engine room was a very uncomfortable place to be due to the noise and heat generated by these monster engines. Overheated bearings required hosing down with water which together with oil, sprayed everywhere. The quadruple expansion engines were disbanded in favour of a new development in engines, the steam turbine engine. However, the triple expansion steam engine which had proved both reliable and efficient was continued in many vessels for years to come.

This revelation confirms that the above witness comment was probably true. It seems from the literature that the Waratah was fitted with problematic engines which could be considered a developmental failure. It is strange that none of the other numerous witness accounts at the Inquiry referred to unusual vibrations emanating from the engines. I would think under normal, economical operating conditions the engines' vibrations were not as noticeable on the upper decks. 

Irrespective, the literature claims that quadruple expansion engines caused hull strain, which clearly was one one of the main reasons why they were discontinued. The constant vibration would set up a similar vibration within the rivets potentially causing them to snap and brittle hull plates to crack. This is undoubtedly a recipe for disaster in a steamer already overloaded and with a history of grounding at Adelaide. Captain Ilbery probably took these factors into consideration when deciding to come about rather than subjecting the Waratah's hull to further, undue strain confronting the severe storm developing further to the south. Striking a reef or other object would have been the last straw for a stressed hull and the Waratah would have foundered within minutes.

See:

http://waratahrevisited.blogspot.co.za/2016/04/waratah-was-under-powered.html

http://waratahrevisited.blogspot.co.za/2016/04/needed-12000-tons-cargo-for-stability.html




1 comment:

Mole said...

Thanks for expanding on this.Don't forget to buy Andrew's book on Amazon! Mole













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