Lave, one of the Aetna class's French half-sisters. |
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| Class overview | |
|---|---|
| Name: | Aetna |
| Operators: | Royal Navy |
| Succeeded by: | Erebus-class ironclad floating battery |
| Built: | 1854-56 |
| In service: | 1855-73 |
| Building: | 6 |
| Planned: | 5 |
| Completed: | 5 |
| Lost: | 2 |
| Retired: | 4 |
| General characteristics | |
| Class and type: | Aetna class floating battery |
| Tonnage: | 1,469 BOM 1,535 BOM broad beam 1,588 BOM lengthened Aetna[1] |
| Length: | Overall 172 ft 6 in (52.58 m) 186 ft 0 in (56.69 m) lengthened Aetna Keel 146 ft 0 in (44.50 m) 157 ft 9 in (48.08 m) lengthened Aetna[1] |
| Beam: | 43 ft 11 in (13.39 m) 45 ft 2.5 in (13.780 m) broad beam 43 ft 11 in (13.39 m) lengthened Aetna For tonnage 43 ft 6 in (13.26 m) 44 ft 9.5 in (13.653 m) broad beam 43 ft 6 in (13.26 m) lengthened Aetna[1] |
| Draught: | 8 ft 8 in (2.64 m) 6 ft 0 in (1.83 m) lengthened Aetna[1] |
| Propulsion: | single screw, two cylinder horizontal single expansion 150 nhp engines[1] generating 530 ihp (400 kW) on Meteor's trials.[2] (200 nhp for lengthened Aetna)[1] |
| Sail plan: | Three masts 885 m2 (9,530 sq ft) sail[3][4] |
| Speed: | 4.5–5.5 kn (8.3–10.2 km/h) 4 knots (7.4 km/h) lengthened Aetna[1] |
| Complement: | 200 men[1] |
| Armament: | 14 x 68 pdr 95 cwt smoothbores 16 x 68 pdr 95 cwt smoothbores lengthened Aetna[1] |
| Armour: | 3.5-4 inch (90-100 mm) wrought iron 4 inch (100 mm) wrought iron lengthened Aetna[1][2] |
The Aetna-class ironclad floating batteries were built during the Crimean War for the attack of Russian coastal fortifications.
Britain and France each laid down five of these coastal attack vessels in 1854. The French used three of their batteries in 1855 against the defences at Kinburn on the Black Sea, where they were effective against Russian shore defences. The British planned to use theirs in the Baltic Sea against Kronstadt in 1856, and were influential in causing the Russians to sue for peace.[5] The development of such iron-armoured batteries was step towards the development of ironclad warships. "These armoured batteries were among the most revolutionary ships ever built and provided British and French designers with the germ of the battleship."[2]
One of the British batteries, the Trusty was used for trials in 1861 with a prototype rotating turret, based on Captain Cowper Phipps Coles designs.
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Emperor Napoleon III initiated the design of armoured steam-powered batteries for the French Navy. The original idea was to protect the sides with boxes of cannon balls, but the British engineer Thomas Lloyd suggested using thick wrought iron plates instead. Trials at Vincennes showed that Lloyd's idea was more effective, so it was adopted.[2]
Napoleon wanted ten floating batteries built in time for the 1855 campaign, but as French industry could only build five in time, France's British allies were asked to build the other five.[2] Unfortunately the First Lord, Sir James Graham confused this concept with the unsuccessful iron-hulled frigates built in the late 1840s, and asked for further trials,[6] so the British armoured batteries were not ordered until 4 October 1854.[2]
These vessels were copies of the French Dévastation-class batteries. The French batteries carried 16 guns, but had 24 gun ports. The British Aetna class were also intended to carry 16 guns, but the first four completed only carried 14 guns to reduce draught to 8 ft 8 in (2.64 m).[1][2] The Admiralty design drawing showed them with 32 gunports.[1] These ports were very large 34 in (0.86 m) x 40 in (1.0 m).[2]
The Aetna class had "wooden hulls, straight vertical sides and a flat bottom with a very bluff bow and stern. Their armour plates, nominally 4in [100mm] but in many cases rolled 0.25-0.5in under thickness, were locked together with tongue and groove joints."[2] The iron armour was supported by 20 in (510 mm) thick oak sides.[7] The wooden upper deck was 9 in (230 mm) thick.[2] There were two conning towers protected by 5⁄8 in (16 mm) wrought iron plate.[2]
In October 1858, experimental firing trials were undertaken against the Meteor and one of the follow-on class of iron-hulled armoured batteries, the Erebus. These demonstrated the importance of wooden backing for the armour, as the Meteor put up far better resistance than Erebus, where the frames were displaced by concussion.[7]
The first four completed had two-cylinder 25.5 in (0.65 m) diameter 24 in (0.61 m) stroke horizontal single expansion engines of 150 nhp, which operated at 62 psi (430 kPa).[1] Although they were completed as single screw vessels, the Meteor was altered to triple screw with wing-shafts;[1] her trials with triple screw were 12 days after her trials with single screw.[2] The most likely method of driving the wing shafts was a belt arrangement, which was common practice at the time.[2] It is unclear whether any of the others were also altered to triple-screw.[1]
On trials with a single 6 ft (1.8 m) diameter, 12 ft 6 in (3.81 m) pitch screw, Meteor reached 5.7 knots (10.6 km/h) at 139 rpm with the safety valve set at 60 psi, and engine power was recorded as 530 ihp (400 kW).[2] On her trials fitted as triple screw, the Meteor reached 5.25 knots (9.72 km/h) at 139 rpm. Engine power was recorded as 498 ihp (371 kW).[2] The two wing screws on this trial were 6 ft (1.8 m) diameter, 7 ft 6 in (2.29 m) pitch.[2]
Aetna (ii) had two-cylinder 27 in (0.69 m) diameter 30 in (0.76 m) stroke horizontal single expansion engines of 200 nhp. Her boilers were salvaged from Aetna (i).[1]
| Ship | (a) Hull builder (b) Main machinery manufacturers |
Ordered | Laid Down | Launched | Completed | Initial cost | Total Initial Cost |
||
|---|---|---|---|---|---|---|---|---|---|
| Hull | Machinery | to complete for sea |
|||||||
| Aetna class | |||||||||
| Aetna (i) | (a) J Scott Russell, Millwall (b) J Scott Russell |
4 Oct 1854 | 9 Oct 1854 | 3 May 1855 | Never | Never delivered, caught fire during construction | |||
| Meteor | (a) CJ Mare & Co, Limehouse (b) Maudslay, Sons & Field |
4 Oct 1854 | 9 Oct 1854 | 17 Apr 1855 | 4 Jul 1855 | £43,799 | £10,123 | £7,468 | £61,390 |
| Thunder | (a) CJ Mare & Co, Limehouse (b) Miller, Ravenshill & Co |
4 Oct 1854 | 9 Oct 1854 | 17 Apr 1855 | 21 Jul 1855 | £43,784 | £10,343 | £8,210 | £62,337 |
| Broad beam Aetna class | |||||||||
| Glatton | (a) R & H Green, Limehouse (no 314) (b) Miller, Ravenshill & Co |
4 Oct 1854 | 9 Oct 1854 | 18 Apr 1855 | 3 Aug 1855 | £43,479 | £11,244 | £5,858 | £60,581 |
| Trusty | (a) R & H Green, Limehouse (no 315) (b) Miller, Ravenshill & Co |
4 Oct 1854 | 9 Oct 1854 | 3 May 1855 | 13 Jun 1855 | £43,491 | £10,446 | £10,004 | £63,941 |
| Lengthened Aetna class | |||||||||
| Aetna (ii) | (a) Chatham Dockyard (b) Maudslay, Sons & Field |
16 Nov 1855 | 25 Nov 1855 | 5 Apr 1856 | 1866 Harbour service |
£38,357 | £11,000 | £495 | £49,852 |
| Source: Lyon & Winfield, pages 240-2[1] | |||||||||
Note that whilst Admiralty records for Meteor, Thunder, Glatton and Trusty state that both the Mare and the Green yards were at Limehouse, other vessels built by Mare and by Green were built at Blackwall. It is possible that there is an error in the records, and they were really built at Blackwall.[1]