Friday, 2 June 2017

SIMILAR STABILITY ISSUES.

 SS INDARRA:                                 

Builders:    William Denny & Brothers, Dumbarton

                                                                      SS WARATAH:

Engines:     twin quadruple                                     same

Launched:  1912                                                     1908

Gross tons: 9735                                                     9339.07

Length:       450 ft.                                                  465 ft.

Beam:         60 ft.                                                    59.45 ft.

Draught:      32 ft.                                                   30.375 ft.


The Indarra was intended exclusively for the Australian coastal trade. She was built 3 years after the Waratah disaster which was still fresh in the minds of Australians. It is somewhat extraordinary and rather disturbing that Indarra almost matched the Waratah for specifications and prominent top hamper. Note that her draught was even greater than Waratah's. The following extract is illuminating:


A vessel with very much promise was placed in service by the AUSN (Australian United Steam Navigation Co) in 1913. The Indarra was built by Denny and Brothers of Dumbarton in the previous year. Indarra arrived at Fremantle, her Port of Registry on 1 January 1913 and then continued around the coast as far as Brisbane. At each port the liner was opened for public inspection and large crowds streamed aboard to gaze at the magnificent interior fittings. She was without doubt the most palatial liner ever to serve on the Australian coast. Among other fittings she had a marble open air swimming pool, a gymnasium and an electric elevator between decks that impressed the public. Accommodation was provided for 150 first class, 200 second class and 120 third class passengers. The ship appeared to have a promising career in the coastal market. This was not to be the case however as it soon became apparent that she had some serious problems, the most noticeable being an eight degree list to port that raised questions of stability. 80 tons of stone ballast solved this problem but other problems were not easily overcome. Being longer than previous ships it was found that difficulties arose when she was being manoeuvred at the company docks in Melbourne and Sydney. At Albany it was impossible to berth her at all if there was a wind blowing. As coaling had to be done from each side, this necessitated the ship being turned when in dock. It soon became clear that her engines had a heavy demand for coal. Crossing the Great Australian Bight was very uncomfortable as Indarra had a heavy roll which gave rise to rumours that the ship was top heavy. Indarra was left on the coast until requisitioned in October 1917. She was converted by Sid Heatley to a troopship at Sydney and then went to Melbourne to embark a thousand troops. Indarra was later inducted into a convoy of liners to carry troops from Alexandria to Marseilles. After the armistice she was used to repatriate British soldiers from India and other areas and in July of 1918 embarked Australian troops and carried them home. The liner was returned to the AUSN on 24th September but because of the uncertain state of the coastal trade at that time they decided against returning her to her former service. She was then chartered to the Orient Line but she was proved to be too slow and unreliable. In October of 1923 she was sold by AUSN to Osaka Shasan Kaisha of Japan. Renamed the Horai Maru she was given an extensive refit during which the upper part of the superstructure was removed resulting in a reduction in draft that made the vessel more stable. For many years the Horai Maru operated between Kobe and Keelung until the Japanese went to war in 1941 and the vessel was converted into a troop transport. Her war service was to be short as on 1 March 1942 Horai Maru was attacked by a combined force of Allied aircraft and warships in the Sunda Strait and was sunk. In 1947 the wreck was raised by Japanese salvage companies and towed away to be broken up. Prepared for publication by Laurie Bahr.

courtesy: Maritime Times of Tasmania.

The Indarra needed additional stone ballast and the Waratah a hefty load of lead concentrates to enhance dead weight and GM stability. 

Both vessels were difficult to manoeuvre and load in dock settings. 

Rumours of top heaviness shadowed both vessels.

Removing the upper part of the superstructure of the Indarra reduced draught, making her more stable. This is the essence of the top heaviness conundrum. In previous posts the vessels quoted had draughts less than 27 ft. (similar length / beam ratios) but only in the case of Indarra and Waratah were draughts significantly greater, making them technically top heavy as opposed to visually top heavy. This confirms my opinion that Waratah and Indarra had to be functionally overloaded to establish GM stability. Waratah departed Durban for the last time with a GM of 1.5 ft. which is stable, but the weight factor created a hull-strained and unwieldy vessel, exacerbating a sequence of misfortune which was about to unfold along the Wild Coast.

Waratah and Indarra had quadruple expansion engines, which contrary to theory, were heavy on fuel, not as efficient in terms of speed output, caused vibration and were unreliable. It is no wonder that most steamers continued to be fitted with triple expansion engines.

Perhaps the most important message we can glean from insight into the equivalent Indarra is this: she continued in service, without mishap, for many years before the refit. As long as dead weight ballast was taken care of, storms at sea were negotiated without a repeat of the Waratah disaster. What befell the Waratah was more to do with an uncontrolled fire than stability issues. But when the final moment arrived, the heavily laden Waratah went down like a stone.

See:

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







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