HMS Thunderer was a British

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 Devastation-class battleship

Devastation class battleship

The two British Devastation-class battleships of the 1870s were the first class of ocean-going capital ship that did not carry sails, and the first which mounted the entire main armament on top of the hull rather than inside it...

.

Thunder was an ironclad

Ironclad warship

An ironclad was a steam-propelled warship in the early part of the second half of the 19th century, protected by iron or steel armor plates. The ironclad was developed as a result of the vulnerability of wooden warships to explosive or incendiary shells. The first ironclad battleship, La Gloire,...

 turret ship

Turret ship

Turret ships were a 19th century type of warship, the earliest to have their guns mounted in a revolving gun turret, instead of a broadside arrangement....

 designed by Edward James Reed

Edward James Reed

Sir Edward James Reed , KCB, FRS, was a British naval architect, author, politician, and railroad magnate. He was the Chief Constructor of the Royal Navy from 1863 until 1870...

 with revolving turrets, launched in 1872. The new innovations introduced on these ships led to them being regarded with some suspicion, and this was partly justified when two unfortunate incidents clouded the initial success of the design.

On 14 July 1876 shortly after completion she suffered a disastrous boiler

Boiler

A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...

 explosion which killed 45 people when one of her eight 30 pound per square inch (210 kPa) box boilers burst as she proceeded from Portsmouth Harbour

Portsmouth Harbour

Portsmouth Harbour is a large natural harbour in Hampshire, England. Geographically it is a ria: formerly it was the valley of a stream flowing from Portsdown into the Solent River. The city of Portsmouth lies to the east on Portsea Island, and Gosport to the west on the mainland...

 to Stokes Bay

Stokes Bay

Stokes Bay is an area of the Solent that lies just south of Gosport, between Portsmouth and Lee-on-the-Solent, Hampshire. There is a shingle beach that has a great view of Ryde and East Cowes on the Isle of Wight to the south and also Fawley in the south west. The village of Alverstoke is close by...

 to carry out a full power trial.

The explosion

Boiler explosion

A boiler explosion is a catastrophic failure of a boiler. As seen today, boiler explosions are of two kinds. One kind is over-pressure in the pressure parts of the steam and water sides. The second kind is explosion in the furnace. Boiler explosions of pressure parts are particularly associated...

 killed 15 people instantly, including her captain

Captain (nautical)

A sea captain is a licensed mariner in ultimate command of the vessel. The captain is responsible for its safe and efficient operation, including cargo operations, navigation, crew management and ensuring that the vessel complies with local and international laws, as well as company and flag...

 who was in the boiler room at the time and injured around 70 others, of whom 30 later died. The reason for the explosion was that the pressure gauge was broken and the safety valves had seized through corrosion

Corrosion

Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...

. The boiler explosion signalled the end of box boilers in favour of the Scotch cylindrical type

Scotch marine boiler

A "Scotch" marine boiler is a design of steam boiler best known for its used on ships.The general layout is that of a squat horizontal cylinder. One or more large cylindrical furnaces are in the lower part of the boiler shell. Above this is a large number of small-diameter fire-tubes...

, and it led directly to the writing of the first official Steam Manual in 1879.

Thunderer suffered another serious accident in January 1879 when the left 12 inches (305 mm) gun in the forward turret exploded during practice firing in the Sea of Marmora killing 11 and injuring a further 35. The reason for this accident was that the muzzle-loading gun had been double loaded following a misfire, and was a major reason for the Royal Navy changing to breech loading guns. It led to improved loading and handling procedures, and Thunderer herself was re-equipped with long-calibre 10" breech-loaders, and settled down in her old age to become a favourite of the Fleet: King George V

George V of the United Kingdom

George V was King of the United Kingdom and the British Dominions, and Emperor of India, from 6 May 1910 through the First World War until his death in 1936....

 served in her for a while as Lieutenant Prince George of Wales. With her broad beam she was a fine gun-platform, and the phrase "As steady as the old Thunderer" was high praise for any newcomer to the Navy.

She was refitted in 1881 and equipped with triple expansion engines, which roughly halved her coal

Coal

Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

consumption at 80% power (and thus doubled her range), paving the way for the widespread introduction of these engines in the Royal Navy.

Further extensive modifications were carried out in 1890-1892.