8-inch Coastal Defense Guns
by Dirk H.R. Spennemann
Turret and Shields
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8-inch Coastal Defense Guns by Dirk H.R. Spennemann Turret and Shields |
In the literature as well as by personal observtion three different types of turrets have been encountered in Micronesia. All such turrets served single, long barrelled naval guns. Short (12 cal.) eight-inch guns have not been recorded with turrets or shields.
For want of access to the original type specifications and for convenience, the type nomenclature adopted in this background report has been based on their occurrence: Sapuk types #1 and #2, Betio, and Eneen-Kio.
The eight guns emplaced on Betio and Moen are in single turrets. Yet, the vessels they are believed to have come from (see below) have a different configuration. The Italian Garibaldi Class of cruisers has a 10-inch gun on the bow and a twin turret with 8-inch guns aft.[1] The Kasuga had the same configuration, while the Nisshin had a twin 8-inch turret in the bow instead of the 10-inch gun.[2]
Thus, while the barrels themselves may certainly have come from one of the two Italian vessels, the turrets certainly have not. These may have either come from other ships, such as scrapped cruisers, or may been manufactured for the purpose. As we will see further below, there is a variation in the turrets, which suggests some modifcation of extant turrets, as well as an outright construction of others. Single 8-inch turrets had been emplaced on the Elswick-built Takasago, which had been built for the Japanese Navy in 1896-1898.[3]
Figure 6. Sapuk, Moen Is. Chuuk Atoll. . Type #1 Turret.
A high, box–like turret of rectangular plan with a rounded front. The turret has a firing port in the centre, one observation and gunlaying window on either side of the port. Port and windows had been protected by shields which were hinged at the top (figure 6). The turret had two side windows to allow access for ammunition, as well as a large rear opening for the same purpose, as well as for the access for personnel.
The turret is made up of pieces of armourplate which are held together by a double row of rivets each. Whilst the thickness of the front armour plate has not been measured, that of the sides (and presumably also the top) was one inch (25mm).
The turrets are set on a motor pit, access to which is from the inside of the turret, to the right of the gun barrel. The bottom of the turrets consists of thin, 0.5 inch thick metal.
The inner height of the turret is such that a six-foot tall person (such as the author) has barely room to move. However there seems to have been enough room to allow for the sighting telescopes to remain mounted at the gun even with the barrel at its most depressed angle. The Sapuk #1 turrets had the elevation marked out on the inside of the turret, with a projecting metal bar attached to the gun barrel (see figure 4).
At the rear of the turret (inside) is a shell hoist fastened to the top, which runs around the entire back and ends at the side windows. At the sides of the turret there are trough-like receptacles, where semi-fixed propellant cartridges could be stored. The 250lb-heavy projectiles were stored on an ammunition trough to the left of the gun barrel, and could be placed into the breech by moving a foldable tray into position.
Two reinforcement struts, near the breech, provide for stability of the turret’s roof.
This turret has the apperance of one manufactured ‘on the fly’ and assembled on the spot.
This type of turret has been seen on Sapuk, Moen, Chuuk Atoll (pers, observation). Two of the three turrets at Sapuk investigated by the author were of this type, and both carried Stabilimento Armstrong-Pozzuoli models of 8- inch guns.
Figure 7. Sapuk, Moen Is. Chuuk Atoll. Turrets. type #2 Turrets.
The turret comprises of two distinctly different parts. The front, which is flat in the middle and slopes at the sides, and the rear, which appears like a box added on. The turret has a firing port in the centre, one observation and gunlaying window on either side of the port. Port and windows had been protected by shields which were hinged at the top (7). The roof of the front part of the turret shows two little boxes where the roof is heigthened, These allow for the sighting telescopes to remain mounted at the gun even with the barrel at its most depressed angle.
The turret had two side doors at the heightened back part to allow access for ammunition, as well as a large rear opening for the same purpose, as well as for access for personnel.
The turret is made up of pieces of armourplate. The front parts seem to be held together by a single row of large bolts, while the rear part of the turret is made up of armourplates held together by a double row of rivets each. Whilst the tihckness of the front armour plate has not been measured, that of the sides and the top is one inch (25mm).
The turrets are set on a motor pit, access to which is from the inside of the turret, to the right of the gun barrel. The bottom of the turrets consisted of thin, 0.5 inch thick metal. The inner height of the turret is such that a six-foot tall person (such as the author) has barely room to move.
At the rear of the turret (inside) is a shell hoist fastened to the top, which runs around the entire back and ends at the side windows. At the sides of the turret there are trough-like receptacles, where semi-fixed propellant cartridges could be stored. The 250lb-heavy projectiles were stored on an ammunition trough to the left of the gun barrel, and could be placed into the breech by moving a foldable tray into position. Two reinforcement struts, near the breech, provide for stability of the turret’s roof.
This type of turret has been seen on Sapuk, Moen, Chuuk Atoll (pers, observation). It carried an Armstrong-pattern gun.
Figure 8. Wartime photograph of a 200mm Naval gun on Betio, Tarawa Atoll, Kiribati (from CinCPac–CinCPOA 1945)
This turret is very similar to the Sapuk Type #2 turret. The front of the shield is rounded and backwards it (just) extends to cover the breech of the gun. The turret has a firing port in the centre, one observation and gunlaying window on either side of the port. Port and windows had been protected by shields which were hinged at the top (figure 11). The roof of the front part of the turret shows two little boxes where the roof is heightened, These allow for the sighting telescopes to remain mounted at the gun even with the barrel is at its most depressed angle. As the front the Betio type turret is therefore identical to that of the Sapuk #2 type. A door on each side (opening to the outside with a hinge to the front) allows the entrance of pointers and trainers. The sides of the turret are then carried downwards and around the back. A davit-type crane has been provided at the left of the gun to allow for shells being placed in the ammunition trough. The rear of the turret, as well s the sides had provisions and props to allow for a sun sail to be fastened to it.
Some battle data exist for this type of turret. A shield of one gun on the SW corner of Betio could withstand five U.S. 5' direct hits, while the turret of a gun emplaced in the S.E. battery was hit by 16' naval shells, which devastated the emplacement, and severely damaged the turret.
This type of turret has been seen on all four 8-inch guns emplaced on Betio Island, Tarawa Atoll, Kiribati (Bartsch 1977; OPNAV 1945a). It appears to be the basic semi-open type of turret, which was then modified for local conditions to become a Sapuk Type #2 turret or an Eneen-Kio type turret. The placement of the access doors at the sides may prove to be a discriminant feature between true Betio-type turrets and a second model, later modified to become the Sapuk Type #2
The rear of the Betio turret is open, thus exposing the gun crew to direct sunlight. To provide for shade, a canvas top was set up at Betio, while the solution at Eneen-Kio seems to have been to provide for a wooden enclosure. Sapuk, which seems to have been developed after the fall of Betio, and later than Eneen-kio, saw a defensive rear of the turret.[5]
A turret type very similar that observed at Betio was also found on Eneen-Kio (Cohen 1983, p. 89, 95, 103). The rear of the turret, however, was covered with a wooden compartment. Ammunition provision was safe-guarded by a shell hoist consisting of two I-beams, which fed the shells straight into the ammunition trough (figure 12).
Figure 9. Reconstructed technical drawing for a Sapuk type #1 turret
Figure 10. Reconstructed technical drawing for a Sapuk type #2 turret
Figure11. Reconstructed technical drawing for a Betio type turret
Figure 12. Reconstructed technical drawing for a Eneen-Kio type turret