Tuesday, 15 March 2016

PROGRESS AND STABILITY.

Kalgoorlie Miner, Saturday 10 July, 1920


In modern vessels, such as the
15,500 Maldera, which with her sister
ship, the Narkunda, has just been 
added to the company's (P&0) fleet, the 
superstructure assumes enormous 
proportions, so that the hull itself looks 
almost insignificant under such
towering overload. Sailors of the 
old school do not usually approve 
of this development in marine architecture 
but for passenger service it must justify itself. 
In the P. and O. it commenced with the
'spar-decks' on the Assam and
Siam, launched in 1873. These 
steamers, it is said, were the 
earliest, or among the earliest, examples 
of their kind. The idea was to ensure coolness 
in tropic seas for passenger accommodation, 
and as it was successful the design was
copied by other companies. In the course
of time deck after deck was added, until we 
get the five or six storey buildings carried on 
the hull of the modern liner. Laymen sometimes 
regard very high superstructures with disfavour, 
because they consider they make steamers top-heavy. 
This is an error, for all vessels, are so designed that the 
centre of gravity is kept down to a point that 
will ensure stability. It has been said that the 
development of the superstructure for passenger ships 
has been continuous, but a curious exception to the rule 
may be seen in the P. and O. Parramatta and Ballarat. In these, 
there is a reversion to the flush deck ; the type, however, 
was not repeated.

The writer captured the concerns regarding prominent top hampers and made the simple but accurate
point that the centre of gravity had to be low in the vessel to establish the all-important GM stability
factor.

It is very interesting to note that the trend was reversed with the Ballarat (see previous post) which was
probably as a result of the Waratah tragedy. But reservations did not last long and progress continued
until the present day cruise liners.

The Narkunda was launched 1920. Built by Harland Wolff of Belfast, she comprised 16227 gross tons,
9705 net tons, 581.4 ft. in length, beam 69.4 ft., depth, 48.9 ft. and draught 29.25 ft. She was powered
by twin quadruple expansion engines, giving 17.5 knots. She carried 426 first class and 247 second
class passengers. 

Note that she had a freeboard of 19.65 ft., which exceeded the 1908 recommendation of 14.5 ft.for her length. Although top hampers were significant, more attention was given to freeboard and reserve buoyancy. Narkunda's draught was 60% of depth, whereas Waratah's was a whopping 79%. Progress was in full swing and Narkunda's naval architect was able to create a stable steamer with significant top hamper without resorting to overloading which reduced reserve buoyancy among other factors. Further to this Narkunda's superstructure spanned more than 50% of the length of the hull.



Narkunda


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