Trans RINA, Vol 152, Part A2, Intl J Maritime Eng, Apr-Jun 2010
ENABLING TECHNOLOGY AND THE NAVAL ARCHITECT 1860-2010 I Buxton BSc, PhD, CEng, FRINA
SUMMARY (DOI No: 10.3940/rina.ijme.2010.a2.171)
Enabling technology permits the naval architect to do more with fewer resources, increasing output, decreasing cost and improving productivity, with the resulting benefits being widely distributed in a worldwide economy. For example a bulk carrier’s energy consumption per ton-mile today is less than 3% of what it was a century and half ago – due to more efficient machinery, larger hulls with lower resistance per ton and improved propulsive efficiency, yet with higher speed and shorter port times
1. THE FIRST HALF CENTURY
The state of the art in naval architecture in the 1860s was well described by John Scott Russell, one of the founders of the Institution of Naval Architects (INA, later to become The Royal Institution of Naval Architects – RINA),
in his “A Modern System of
riveted construction. Isherwood’s system was widely used for tankers from 1908.
Naval
Architecture”, published in 1865. These massive tomes weighing 50 kg together and costing £42 then (about £3000 in today’s money) consist of one volume of text and two of plates, the latter illustrating such vessels as the Great Eastern built by Russell himself. The 1860s were still a period of transition, from sail to steam and wood to iron. Although steam propulsion dated back half a century for small wooden paddle steamers, 45% of the 500 ships over 100 tons built a year from 1859 to 1861 in the British Isles were wood (43% by tonnage, 250,000 including naval vessels). Sail was still a significant part of output, 60% by number, 45% by tonnage. Of the 180 steamers built each year over 100 tons, 55 were paddle (30% by number, 21% by tonnage). Cunard’s latest passenger liners Persia and Scotia were still paddle propelled, albeit with iron hulls.
The thermal efficiency of most steam reciprocating engine was low at about 8% (2.5 lb coal/hp-h specific fuel consumption - SFC) which limited endurance as well as increasing fuel cost. Although a handful of screw steamers had been built in the mid 1850s with compound engines (one high pressure cylinder and one low), most were two cylinder simple expansion engines with boiler pressures of around 20 lb/sq in (1.3 bar).
Britain at that time built the vast majority of the world’s steamships and British shipowners had by far the largest fleet of steamships, so its experience and statistics give a good overall picture of developments. Of the steamship types, the greatest number were colliers, ferries and tugs, although the liner companies like Cunard and P&O were expanding their fleets of long distance passenger-cargo vessels. The largest vessels (excluding the unique Great Eastern) were around 3000tons gross, carrying around 800 passengers at speeds of around 12 knots with engines of about 3000 ihp (2250kW) (indicated horsepower, the measure of steam reciprocating engine power, about 80% of shaft power).
Figure 1. John Scott Russell’s magnum opus “A Modern System of Naval Architecture” of 1865 included many illustration of contemporary ships and structures, some of
them his own passenger design. cargo vessel
His 190ft Annette
(58m) 750grt was framed
longitudinally, and illustrated in his 1862 INA paper. But it was nearly fifty years later before such framing came into wider use, as transverse framing was easier build in
Figure 2. The steam paddle tug was developed from the 1820s and by 1860 not only assisted ships in harbour or distress but enabled sailing vessels to get in and out of harbour when winds were adverse. Flying Irishman of 1885 was typical, 120ft long (36m) and engines of about 400 ihp.
On the theoretical side, Scott Russell had expounded his wave-line principle for hull forms, William Rankine had established the basics of ship strength (important for
©2010: The Royal Institution of Naval Architects A - 51
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