Firstly it was intended to reduce the considerable damage caused by the teredo woodworm, and secondly the well-established toxic property of copper was expected to lessen the speed-killing barnacle growth which always occurred on ships' hulls.

It was soon discovered that the sheathing had become detached from the hull in many places because the iron nails which had been used to fasten the copper to the timbers had been "much rotted".

[6] In the meantime the copper sheathing was removed from Alarm, and several other test vessels until an effective solution to the corrosion problem could be developed.

[7] On the return voyage to England, on 6 April 1770,[8] she was saved by Georges René Le Peley de Pléville from being wrecked off Marseilles.

Alarm had been battered by a storm in the evening and ran aground on the coast of Provence amongst boulders, and was in imminent danger of breaking up.

Remarkable in its elegance of form and high level of finish and workmanship, this vase bore the English Coat of Arms, and had the following inscription, intended to preserve the memory of the event which had merited the present: Georgio-Renato Pleville Le Pelley, nobili normano Grandivillensi, navis bellicœ portusque Massiliensis pro prœfecto, ob navim regiam in litiore gallico pericli – tantem virtute diligentiâque suâ servatam septem vin rei navalis Britannicœ.

([Presented] to Georges-René Pléville Le Pelley, noble Norman of Granville, commander of a warship and of the port of Marseilles, because he saved from destruction a Royal Navy vessel which was about to be lost on the French coast – the seven lords of the British Admiralty [presented] this [for] the great courage and diligence he showed.

1770)Thinking that he could not receive a gift from a foreign sovereign, de Pléville only accepted the urn after having been duly authorised to do so by the king of France.

[9]Ten years later, de Pléville's devotion to the safety of the Alarm gained another reward, when his son – a young naval officer – was captured on board a frigate at the end of a battle in 1780 and taken to England.

[a] On 23 November 1796 Alarm, under the command of Captain Fellowes, was cruising off Grenada when she encountered the Spanish corvette Galgo and captured her.

Alarm shared with Amphion in the head-money that was finally paid in March 1829,[13] for the capture of a Spanish gunboat, Nuestra Senora del Corvodorvya (alias Asturiana), on 25 November 1799.