October 1894: The aluminium torpedo boat

A visit to Engineer Towers 110 years ago would have caught our predecessors in a state of excitement most atypical of the Victorian gentlemen. London was aflap, it seems, over the exhibition of a boat in the Thames which appeared to defy the norms of military craft design. As yet unnamed, this was a torpedo boat which a Poplar-based shipbuilder called Yarrow & Co had built for the French Navy. “Ten tonnes with steam up and coal in the bunkers; twenty and a half knots speed; 300 horsepower. Ten years ago — perhaps five years ago — the man who suggested the possibility of producing a boat which could live in a sea and satisfy the conditions embodied in the lines above would have been regarded as a lunatic by those who had not watched the progress of events,” the journal expounded breathlessly.

The boat’s secret was that it was made from aluminium; indeed at 60ft (18.2m) long and 9ft3in (2.8m) across the beam it was not only the largest aluminium ship ever made at that point, it was the largest aluminium structure of any kind.

Aluminium was by no means a new material in 1894; it had first been isolated in 1825. But it had long been something of a curiosity. It was so difficult to produce in the 1850s and 60s that it was more valuable than gold, and in 1884 the largest piece ever cast was installed as the capstone for the Washington Monument in the US (it weighed 2.8kg, and 30g of the metal cost more than an average day’s wages). In 1893 the first ever cast aluminium sculpture was installed in London; it’s still there, in Piccadilly Circus (universally known as Eros, even though it’s actually called The Angel of Christian Charity and was never intended to depict Eros). But even that isn’t large, so for a whole boat to appear a mere year later made from this fabled lightweight metal must have been a curiosity indeed.

The vessel was a second-class torpedo boat, a type designed to be carried on the deck of a larger warship and launched at need, so lightweight construction was a necessity.

The Engineer reported that Yarrow had carried out extensive tests on aluminium, whose structural properties were then little known; and had determined that to increase its tensile strength it had been determined hat it was best alloyed with 6 per cent of copper. The article states that the hull weight was two tons; about half that of a comparable steel boat; moreover, the beam was 9inches wider than a British 60ft boat. It had cost about £1000 more than a steel boat (which an online calculator tells us is a little under £91,000 in today’s money) but was 3.5knots faster. It was also extraordinarily quiet: ‘On Saturday she was run at a variety of speeds from dead slow up to the highest available, and at none was the slightest vibration to be felt in any part of the boat forward, aft or amidships,” it noted: . “The only species of the kind was a sort of purring thrill.” While steel magnified every sound on a boat, aluminium seemed to deaden it: “The new metal acting very much like wood.” This would give it unheard-of stealth opportunities, it added.

The Engineer proclaimed the boat “the best torpedo boat of the size that has ever been produced.” Later reports are patchy; it appears that it was named La Foudre and some reports suggest that it suffered from corrosion. In any case, the use of aluminium was adopted by Navies worldwide as a superstructure material, but this was relatively shortlived. The metal does not respond well to heat; despite its perception as a relatively inert material, it is highly chemically reactive in in the wrong circumstances highly flammable. Moreover, at high temperatures it loses strength rapidly. The US Navy stopped using it for superstructure after a missile cruiser called USS Belknap collided with an aircraft carrier in 1975 and caught fire, with its superstructure being completely destroyed. Although it is sometimes reported that the Royal Navy’s HMS Sheffield, which sunk during the Falklands war in 1982, burned because it was made of aluminium, this is in fact not true: Sheffield had all-steel hull and superstructure, and the fire which doomed it resulted from an Exocet missile damaging its firefighting systems. The Royal Navy in fact also abandoned aluminium structure in the 1970s after several shipboard fires.