Dirk H.R. Spennemann, 8-inch Coastal Defense Guns

8-inch Coastal Defense Guns
by Dirk H.R. Spennemann
Ammunition supply

Type of ammunition

The following types of ammunition for the 8-inch guns have been identifed (U.S. War Office 1953b):

20cm/short (202mm) (8-inch) Complete Round (semi-fixed). Cartridge 11-inch long, 18.5 lbs weight, plus 4.4lb propellant.
Ordinary Mk. 1 20cm/short (202mm) (8-inch) High Explosive. 110 lbs, 21.9inch long, 201.5mm diameter at borroulet. equipped with mechanical time fuzes or point detonating fuzes.
Year 91 20cm/202mm (8-inch) Armour Piercing. 276.8lbs, 35.8 inches long with base fuze.
Ordinary Type 0 20cm (202mm) (8-inch) High Explosive. 383.2lbs, 36.2 inches long with mechanical time fuze or point detonating fuze (usually for Mk II 8-inch 50 caliber gun).
20 cm (202mm) (8-inch) Catridge case (semi-fixed), 15.3 inches long, 18.6lbs weight (for type 38 8-inch, 45 cal. guns)

Ammunition supply

The ammunition supply occurred via narrow gauge railway with hand drawn cars from a shielded ammo depot to an ammunition ready magazine near the guns.

When extracted from the ammunition storage magazines (see below) the ammunition is placed on an 8-inch-wide ammunition trough which almost encircles the gun. This trough, which stands 0.6m (2 feet) high allows the gun crew to retrieve shells at any given orientation of the turret.

Figure 16. 8-inch gun at Sapuk (#2), Moen Is., Chuuk Atoll. Ammunition loading tray at the left of the gun barrel. Note the differential corrosion of the barrel (photo: D.H.R. Spennemann)

A davit-type hoist lifted the 250kg shells from the railway onto the ammunition trough. Using the davit-type crane mounted on the gun turret, the shells were lifted from the trough onto a loading tray in the turret (left of the barrel) and placed into the breech by moving the foldable tray into position.

Gun laying

In the main, the gun was trained and pointed electrically, but could also be aimed manually. After each firing the bore of the gun was cleaned with an air blast from compressed air tanks.

Staff

Two guns, as well as the fire control and the ammunition train from the main storage to the gun emplacements were staffed by 63 men, according to captured Japanese documents relating to the two guns at Betio’s S.W. point. During combat an additional 12 labourers were seconded for ammunition handling (ISSMD/JICPOA 1943:11).

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Bibliographic citation for this document

Spennemann, Dirk H.R. (2000). 8-inch Coastal Defense Guns. British, Italian and Japanese Naval Guns and their Emplacements in Micronesia.
URL: http:/marshall.csu.edu.au/Marshalls/html/Sapuk/Sapuk.html

CONTACT:
Dirk H.R. Spennemann, Institute of Land, Water and Society, Charles Sturt University, P.O.Box 789, Albury NSW 2640, Australia.
e-mail: dspennemann@csu.edu.au