Duncan Class Battleship (1901)

Overview of 6 vessels
Citations for this data available on individual ship pages
Name	Builder	Laid Down	Launched	Completed	Fate
Albemarle	Chatham Royal Dockyard	8 Jan, 1900	5 Mar, 1901	12 Nov, 1903	Sold 19 Nov, 1919
Cornwallis	Thames Ironworks, Shipbuilding and Engineering Company, Blackwall	19 Jul, 1899	13 Jul, 1901	9 Feb, 1904	Torpedoed 9 Jan, 1917
Duncan	Thames Ironworks, Shipbuilding and Engineering Company	10 Jul, 1899	21 Mar, 1901	3 Oct, 1903	Sold 18 Feb, 1920
Exmouth	Laird	10 Aug, 1899	31 Aug, 1901	Jun, 1903	Sold 15 Jan, 1920
Montagu	Devonport Royal Dockyard	23 Nov, 1899	5 Mar, 1901	27 Jul, 1903	Wrecked 30 May, 1906
Russell	Palmer Shipbuilding and Iron Company	11 Mar, 1899	19 Feb, 1901	19 Feb, 1903	Mined 27 Apr, 1916

Binoculars

In September 1914, the ships were allowed four additional pairs of Pattern 343 Service Binoculars.

Searchlights

In 1907, battleships of the Majestic, Canopus, London, and Duncan classes, along with armoured cruisers of the Powerful, Drake, Cressy, Monmouth and Devonshire classes were to land their searchlights from their tops and obtain two additional 24-inch models from their dockyards for placement on the shelter or boat deck. These were to be augmented by (or further upgraded to?) a pair of 36-in searchlights when they became available.

Armament

In early 1913, new pattern G. 329 trainer's telescopes of 2.5 power and 20 degree field were issued to these and many other capital ships, to replace the 5/12, 5/15 and 5/21 variable power G.S. telescopes that had previously been in use.

During the war, along with those of other older ships, the eight 6-inch guns casemated on the first deck proved of little use in practical sea states. It was decided to remove the eight casemate guns, plate their ports over and move four of them to the upper deck. Four of the twelve 12-pdr guns were also surrendered due to this alteration.

Main Battery

The four 12-in guns were Mark IX, mounted in twin turrets designated "Fore" and "Aft". However, some vessels had twin B. VI mountings and others twin B. VII mountings.

The guns had 6-pdr sub-calibre guns. In late 1913, .303-in aiming rifles for use inside the sub-calibre guns were to be ordered, replacing the use of .303-in barrels that had previously been attached to the chase of the guns. Two were to be supplied by January 1914, and a further two by April.

B. VI Ships

In Cornwallis and Duncan (as in Queen, London, Implacable and probably Bulwark), the sights and mountings were as follows.

The mountings could be elevated 13.5 degrees and depressed 5 degrees.

The centre sights were limited to 13.5 degrees elevation, which was 15,800 yards for full charge. They had a range gearing constant of 43.33 and range drums provided for full charge at 2475 fps, reduced charge at 2075 fps, as well as for 6-pdr sub-calibre guns and .303-in aiming rifles. Duncan had an additional drum for half-charge firings at 1,500 fps. Muzzle velocity was corrected by adjustable pointer between +/- 75 fps.

The deflection gearing constant for the centre sights was 72.3, with 1 knot equalling 2.7 arc minutes, calculated as 2475 fps at 5000 yards. Drift was corrected by inclining the pivot 1 degree. The sighting lines were 44.03 inches above and 39 inches abreast the bore. No explicit mention is made of a temperature corrector, but there was a "C" corrector able to at least modify the ballistic coefficient by +/- 8%.

The side sighting positions had vertical column sights in which 1 degree of elevation corresponded to 1.05 inches on the strip. Strips were provided for full charge at 2525, 2500, 2475 and 2450 fps, and for reduced charge at 2150, 2125, 2100 and 2050 fps, as well as for 6-pdr sub-calibre and 1-in aiming rifles. Duncan had an additional strip for half-charge firings at 1,500 fps. M.V. was corrected by strip selection. A deflection gearing constant of 146.7 gave 1 knot equal to 1.4 arc minutes, or 2433 fps at 5000 yards. Drift was allowed for by inclining the sight column 1.833 degrees. The sight line was 42 inches above the bore; its lateral position is not documented. There was no temperature corrector or a "C" corrector.

B. VII Ships

Albemarle and Exmouth, generally in common with Venerable and Prince of Wales, had B. VII mountings with the following characteristics.

The mountings could be elevated 13.5 degrees and depressed 5 degrees.

The sights were limited to 13.5 degrees elevation, which was 15,800 yards for full charge. The centre sights had a range gearing constant of 43.33 and range drums provided for full charge at 2475 fps, reduced charge at 2075 fps, as well as for 6-pdr sub-calibre guns and 1-in aiming rifles. Albemarle also had half charge drums for 1500 fps. Muzzle velocity was corrected by adjustable pointer between +/- 75 fps. The deflection gearing constant for the sights was 72.26, with 1 knot equalling 2.7 arc minutes, calculated as 2433 fps at 5000 yards. Drift was corrected by inclining the sight carrier 1 degree. The sighting lines were 42.64 inches above (though this varied) and 42 inches abreast the bore. No explicit mention is made of a temperature corrector, but there was a "C" corrector able to at least modify the ballistic coefficient by +/- 10%.

The side sighting positions had vertical column sights in which 1 degree of elevation corresponded to 1.05 inches on the strip. Strips were provided for full charge at 2525, 2500, 2475 and 2450 fps, and for reduced charge at 2150, 2125, 2100 and 2050 fps, as well as for 6-pdr sub-calibre and 1-in aiming rifles. Albemarle had an additional strip for half-charge at 1500 fps. M.V. was corrected by strip selection. A deflection gearing constant of 146.7 gave 1 knot equal to 1.4 arc minutes, or 2433 fps at 5000 yards. Drift was allowed for by inclining the sight column 1.833 degrees. The sight line was 42 inches above the bore; its lateral position is not documented. There was no temperature corrector or a "C" corrector.

Secondary Battery

Originally, the ship was provided twelve 6-in/45 B.L. Mark VII guns, eight in casemates and four on the upper deck. During the war, this was reduced to eight such guns on the upper deck.

In early 1904, Duncans were taken as an example to illustrate that a proposed prismatic attachment be declined as unnecessary. The foremost starboard casemate gun and the aftmost port gun's left scopes were wooded at about 7 degrees from the centerline. An attachment proposed by Vickers would have permitted these to still be used when firing straight ahead and astern. This frivolity was seen as offering little benefit.

In early 1905, it was approved that the B.L. 6-in guns in Majestics and later battleships should have "A" class cross connected sights, with one V.P. (variable power) 7 to 21 scope and one V.P.D.N. (variable power, day or night) 5 to 12 scope.

In February, 1913, these mountings, along with many other 4-in and 6-in mountings in various capital ships and cruisers were to have illumination added for their training index racers.

Other Guns

Twelve 12-pdr guns, later reduced to eight when the 6-in casemate guns were relocated.

Torpedoes

The ships carried four 18-in submerged tubes:

• two forward, depressed 1 degree and angled 10 degrees before the beam, axis of tube 11 foot 3.5 inches below load water line and 2 foot 3 inches above the deck.
• two aft, depressed 1 degree and angled at 25 degrees abaft the beam; axis of tube 11 foot 3 inches below load water line and 2 foot 3 inches above the deck.

In 1909, as heater torpedo supplies were still growing, these ships were to receive two 18-in Fiume Mark III** H. Torpedoes each.

Fire Control

A fair idea of the fire control in these ships as of September 1906 can be found in instructions recorded for a Battle Practice Albemarle conducted that month.

The general system of wiring between the TSs in ships prior to Lord Nelson class is illustrated in Handbook for Fire Control Instruments, 1914.

The equipment in Montagu is open to conjecture owing to her loss in 1906.

Evershed Bearing Indicators

It is not known if this equipment was ever provided.

Directors

These ships never received directors for main or secondary batteries.

Gunnery Control

The ships' guns were organized in 3 groups:

1. Two 12-in turrets
2. Starboard 6-in guns ("A" & "X")
3. Port 6-in guns ("B" & "Y")

Local Control in Turrets

There was no provision in these ships for local turret control wherein the receivers in the turret could be driven by transmitters in the officer's position at the back of the turret.

Transmitting Stations

According to Frederic Charles Dreyer, Exmouth's Gunnery Officer in 1903, the ship at that stage had no T.S.es, no means of communicating ranges and deflections, and just a single 4.5-foot rangefinder. These innovations were maturing and seeing retrofits in the 2-3 years following.

By 1914 at least, these ships had acquired fore and aft transmitting stations.

A C.O.S. allowed control options of

1. Fore
2. After
3. Separate

Each control group had transmitters (of various type, see below) with a pair of receivers, one wired directly to the transmitter as a tell-tale, and the other fed off the wires going to the distant guns (i.e., the aft guns for the fore T.S. and vice-versa) as a repeat. "These repeat receivers are necessary to keep the idle transmitters in step; when changing back from separate control they are required to enable both halves of the group to be set alike before being paralleled on to one transmitter."

Dreyer Table

These ships never received Dreyer tables.

Fire Control Instruments

By 1909, the ships in this class fell into two or three categories for fire control instruments.

The simplest category is just Montagu, for which no information has been found.

The second group, Albemarle, Cornwallis and Duncan, was outfitted with Vickers, Son and Maxim Mark I instruments with Barr and Stroud rate instruments:

• Vickers range transmitters: 6
• Vickers deflection transmitters: 6
• Vickers combined range and deflection receivers: 6
• Vickers C.O.S.: 3
• Vickers Check fire switches: 6
• Barr and Stroud rate transmitters: 4
• Barr and Stroud rate receivers: 8
• Siemens turret fire gongs: 8 with 2 keys
• Vickers fire gongs: 12 with 4 keys
• Captain's Cease Fire Bells: 18 with 1 key (supplier not stated)

In 1906, Albemarle had large range (three cylinder) and deflection (two cylinder) drums on the aft face of their Fore Control Top to signal 12-in data to the Lower Main Top. The tops signalled their range and deflection to the guns via Mechanical Wire signalling.

Lastly, Exmouth and Russell were fitted with Barr and Stroud Mark II for range and rate, Mark I for orders, and Vickers for deflection:

• Range (B. & S. Mark II): 6 transmitters (12 in Exmouth), 32 receivers
• Orders (B. & S. Mark I): 6 transmitters (12 in Exmouth), 22 receivers
• Rate (B. & S. Mark II): 4 transmitters, 8 receivers
• Deflection (Vickers): 6 transmitters (12 in Exmouth), 26 receivers (30 in Exmouth)

Additionally, this class had the following Siemens fire control equipment:

• Group Switches: 3 (converted by Chatham)
• Turret fire gongs: 8 with 2 keys
• Fire Gongs: 12 (76 in Exmouth) with 4 keys
• Captain's Cease Fire Bells: 18 with 1 key

In Atlantic Fleet firing practice conducted on 26th November, 1907, the lack of F.T.P. sights was alleviated in Albemarle by having one man read the range receivers while the sight setter set range only and a third man read the deflection receivers and set deflection. This ship achieved the highest scores. Russell and Cornwallis used one (two?) men to call out ranges and deflections. In Exmouth, an additional man was used only to call out ranges. Duncan took no special measures to streamline this process, and scored lowest.

It appears that Exmouth's extraordinary number of instruments was a consequence of her finding herself the proving ground for such instruments.^{[Citation needed]}

These ships lacked Target Visible and Gun Ready signals.

See Also

• Wikipedia
• 1906 Battle Practice in H.M.S. Albemarle

Bibliography

• Admiralty, Technical History Section (1920). The Technical History and Index: Alteration in Armaments of H.M. Ships during the War. Vol. 4, Part 34. C.B. 1515 (34) now O.U. 6171/20. At The National Archives, Kew, United Kingdom.
• Admiralty, Gunnery Branch (1917). The Director Firing Handbook. O.U. 6125 (late C.B. 1259). Copy No. 322 at The National Archives. ADM 186/227.
• Admiralty, Gunnery Branch (1918). Handbook of Captain F. C. Dreyer's Fire Control Tables, 1918. C.B. 1456. Copy No. 10 at Admiralty Library, Portsmouth, United Kingdom.