BL 8-inch Mk I – VII naval gun

{{Infobox weapon

|name= Ordnance BL 8 inch gun Mks I - VII

| image= BL 8 inch Mk VII disappearing gun Devonport NZ November 2008.jpg

| image_size = 300

|caption=Mk VII on disappearing carriage at North Head, Devonport, New Zealand

|origin= United Kingdom

|type= Naval gun
Coast defence gun

|is_ranged=YES

|is_bladed=

|is_explosive=

|is_artillery=YES

|is_vehicle=

|is_UK=YES

|service=1884 - 190?

|used_by={{UK}}
Colonial navies of Australia
{{NZ}}
{{SGP}}

|wars=

|designer=Mk I, VI : RGF
Mk VII : EOC

|design_date=

|manufacturer=Mk I, III, IV : RGF
Mk III, IV, VI, VII EOC

|production_date=

|number=

|unit_cost=£6,015Unit price for 10 Mk VII guns on hydro-pneumatic carriages, with 50 rounds per gun, delivered in London, as purchased by New Zealand in 1885. [http://riv.co.nz/rnza/hist/dgun/harbdef1885.htm 1885 New Zealand Harbour defences (Table showing amount required for) Laid on the Table by the Hon. Mr Ballance, with the Leave of the House.] {{Webarchive|url=https://web.archive.org/web/20081015063532/http://riv.co.nz/rnza/hist/dgun/harbdef1885.htm |date=15 October 2008 }}

|variants=Mks III, IV, VI, VII, VIIA

|weight=Mk III & VI : 14 tons
Mk IV : 15 tons
Mk VII : 12 tons
Mk VIIA : 13 tons barrel & breechText Book of Gunnery 1902, Table XII Page 336

|length=

|part_length=Mk III : {{convert|201|in|mm|sigfig=4}}
Mk VII : {{convert|204|in|mm|sigfig=4}}
Mk IV & VI : {{convert|237|in|mm|sigfig=4}} bore

|width=

|height=

|crew=

|cartridge=Mks III, IV, VI : {{convert|210|lb|kg|sigfig=4}}
Mk VII : {{convert|180|lb|kg|sigfig=4}}Different types of shell had different weights : figures are for the gun's heaviest shell. Hence for the Mk VII gun the Victorian Navy Manual of 1895 quotes Common 168 lb, Segment 177 lb, Palliser, Case & Shrapnel 180 lb

|caliber={{convert|8|in|mm|adj=on|sigfig=4}}

|action=

|rate=

|velocity=Mk III : {{convert|1953|ft/s|m/s|sigfig=3}}Mk III : 1953 ft/s firing 210-pound projectile using 104 lb Prismatic Brown powder or 28 lb 12 oz cordite Mk I size 20. Text Book of Gunnery 1902.
Mk IV & VI : {{convert|2150|ft/s|m/s|sigfig=3}}Mks IV & VI : 2150 ft/s firing 210-pound projectile using 118 lb Prismatic brown powder or 32 lb 10 oz cordite Mk I size 20. Text Book of Gunnery 1902.
Mk VII : {{convert|2000|ft/s|m/s|sigfig=3}}Mk VII : 2,000 ft/s firing a 180 lb projectile, with 90 lb black prism powder (gunpowder); or 22 lb cordite MK I propellant size 20. Text Book of Gunnery, 1902Mk VII : Victorian Navy Manuals 1887 and 1895 quote 100 lb Black powder for "battering charge" and 90 lb for regular charge. Muzzle Velocity of 2027 ft/s is quoted with 180 lb projectile and 90 lb charge in the Victorian Navy Manual of 1895

|range=

|max_range= {{convert|8000|yd|m}}12000 yards is quoted for Mk VII gun in the Victorian Navy Manual of 1895

|feed=

|sights=

|breech=

|recoil=

|carriage=

|elevation=

|traverse=

}}

The BL 8 inch guns Mark I to Mark VIIMark I to Mark VII = Mark 1 to Mark 7. Britain used Roman numerals to denote marks (models) of ordnance until after World War II. Hence these were the first 7 models of BL 8-inch naval gun. were the first generations of British rifled breechloaders of medium-heavy calibre. They were initially designed for gunpowder propellants and were of both 25.5 and 30 calibres lengths.

History

Mks I and II were several early proof guns that did not enter British service and Mk V was not made. Limited numbers of 25.5 and 30 calibres guns were produced.

By 1885 the Royal Navy abandoned the 8-inch gun in favour of the 9.2 inch and later the 7.5 inch gun for cruisers, until 1923 when the restrictions of the Washington Naval Treaty led Britain to develop the Mk VIII 8-inch gun in order to arm heavy cruisers with the largest gun allowed by the Treaty.

In the interim Elswick Ordnance continued to develop 8-inch guns in 40 calibre and 45-calibre lengths for export, mainly to Japan.

=Mark III=

Mk III were low-powered 25-calibres guns mounted on :

{{HMS|Bellerophon|1865|6}} as re-gunned in 1885

=Mark IV=

Mk IV were 30-calibres guns mounted in :

Mersey-class cruisers of 1885

=Mark VI=

Mk VI were 30 calibres guns mounted in :

Indian monitors {{HMS|Abyssinia|1870|2}} and {{HMS|Magdala|1870|2}} as re-gunned in 1892

=Mark VII=

Mk VII were lighter 25-calibres low-powered guns firing a lighter 180-pound projectile used to equip Australian colonial navies and Australian and New Zealand coastal defences in response to expected Russian expansionism in the Pacific (The "Russian scares" of the 1880s).

==Naval service==

File:HMCS Gayundah bow view AWM 300016.jpg, 1903}}]]

Mk VII guns armed the following Australian colonial gun vessels :

==Coast defence gun==

File:BL 8 inch Disappearing Gun Fort Queenscliff VIC.JPG, Victoria, Australia}}]]

Mk VII guns were installed on disappearing mountings in Australia and New Zealand as coast-defence guns during the "Russian scares" of the 1880s. In the event, no Russian invasion occurred and the guns were rarely if ever fired.

Four Mk VII coast defence guns were installed at Singapore in the 1880s-1890s : two atop Mount Serapong and two at Fort Tanjong Katong.{{Cite web |url=http://www.fortsiloso.com/museum/8in/8in.htm |title=Fort Siloso. The Gun Museum. 8-inch BL gun |access-date=15 July 2010 |archive-url=https://archive.today/20100111013931/http://www.fortsiloso.com/museum/8in/8in.htm |archive-date=11 January 2010 |url-status=dead}}

Ammunition

File:BL 8 inch common shell Mk I diagram.jpg|{{center|210 pound Mk I common shell}}

Surviving examples

Mk VII at North Head, Devonport, New Zealand
Mk VII at summit of Mount Victoria, Auckland, New Zealand
An unrestored Mk VII disappearing gun at Fort Jervois, Ripapa Island, New Zealand
[https://archive.today/20100111013931/http://www.fortsiloso.com/museum/8in/8in.htm Mk VII at Fort Siloso, Sentosa Island, Singapore] See also [https://www.flickr.com/photos/9977224@N06/2062421119 Photograph at Flickr]
[https://www.flickr.com/photos/9977224@N06/1878444608 Mk VII at Royal Artillery Museum, Woolwich, London]
[https://www.flickr.com/photos/9977224@N06/2085092392 A Mk VII gun from 1885 on hydro-pneumatic mounting] at Fort Queenscliff, Victoria, Australia
A pair of Mk VII guns at High Street in Westgarth / Northcote, Victoria, Australia [http://heritage.darebinlibraries.vic.gov.au/article/381 Northcote's cannons - defending the neighbourhood] {{Webarchive|url=https://web.archive.org/web/20180702011331/http://heritage.darebinlibraries.vic.gov.au/article/381 |date=2 July 2018 }} Darebin Heritage
A pair of Mk VII guns at Kangaroo Battery, Rosny, Tasmania, Australia (INCORRECT, these guns are 8in RML, not BL)

Notes

References

Bibliography

[http://www.cerberus.com.au/manuals_printing.html Additions to 1890 Manual for Victorian naval forces circa. 1895. HMVS Cerberus website]
[http://cgsc.cdmhost.com/u?/p4013coll11,230 Text Book of Gunnery, 1902. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY HARRISON AND SONS, ST. MARTIN'S LANE] {{Webarchive|url=https://archive.today/20120712182551/http://cgsc.cdmhost.com/u?/p4013coll11,230 |date=12 July 2012 }}
Tony DiGiulian, [http://navweaps.com/Weapons/WNBR_8-26_mk1.htm 8"/26 (20.3 cm) Mark VII]

External links

[http://handle.slv.vic.gov.au/10381/110861 Handbook for the 8-inch b.l. gun marks VII and VIIa Land service 1899] From State Library of Victoria.
[http://recordsearch.naa.gov.au/scripts/Imagine.asp?B=4039828 Instructions for 8 inch Rifled Breech Loading Armstrong Gun and Hydro-Pneumatic Disappearing Carriage] Describes Mk VII gun. From Australian National Archives
[http://recordsearch.naa.gov.au/scripts/Imagine.asp?B=4039829 Instructions for 8 inch Rifled Breech Loading Armstrong Gun and Naval Carriage and Slide] Describes Mk VII gun. From Australian National Archives

Category:Naval guns of the United Kingdom

Category:Coastal artillery

Category:203 mm artillery

Category:Victorian-era weapons of the United Kingdom

Category:Disappearing guns