Construction of the tower
These towers also turrets called, were also armored on its upper side and on the entire peripheral side surface. They were therefore also called armored towers . Their construction differed significantly from that of the later turret . They were structured much more simply. Above all, the barbette was missing , there was still no cylindrical shaft in the hull and no rotating ammunition conveyor mechanism. The heavy grenades had to be laboriously pulled up from the ammunition chambers with chain hoists through openings in the tower floor and placed in the loading hollows .
There are two different systems for the towers of that time. In the system developed by the Swedish engineer John Ericsson , the entire weight of the tower rested on the central axis of rotation. Such a tower had z. B. the monitor . The tower type designed by the British Captain Cowper Phipps Coles , for which the Royal Navy decided, had a bearing ring at the bottom of the tower, which resulted in a much better weight distribution. In addition to a few British tower ships, the Danish Rolf Krake (1862), the first tower ship ever to be designed according to Coles' system, the Prussian Arminius (1864) and the single- tower Huáscar (1865) ordered by the Peruvian Navy had armored towers based on this system.
To make loading the guns easier, the British designers temporarily reverted to muzzle-loaders . After the shot, the cannons had to be swiveled in again and their muzzles lowered into openings in the ship's deck , from which the grenades were pushed, bottom first, to the end of the gun barrel by means of steam-operated pistons . During this time-consuming process, the tower could not be moved and in the event of a malfunction in which it was no longer possible to extend the piston again, the entire tower was blocked. After each charging the target had to be targeted again what the zeroing greatly impeded on a goal that also usually moved while the rate of fire is not a disadvantage against the breech-loading method showed.
Due to the heavy smoke development of the black powder , which was used as a propellant charge until around 1890, the use of muzzle-loaders also had the advantage that less smoke could get into the interior of the armored turrets. With breech-loaders, a considerable part of the smoke penetrated into the tower, which made more complex ventilation necessary. However, the use of armored turrets wasn't the only reason the Royal Navy used muzzle loaders. In the case of large-caliber guns in particular, it has long proven difficult to construct reliable breeches for breech-loaders.
The only Coles tower that has survived to this day is on the Huáscar , which can be viewed as a museum ship in the Chilean port of Talcahuano . The rotation of this tower was initially accomplished with human power through a manual turnstile attached below deck, which was operated by 16 men. It was replaced by a machine drive in the 1880s, but can now be seen again in its original design.
Influence on shipbuilding
Since the guns were no longer on the edge of the ship's deck , but in the middle of it, the standing and moving goods of the ship represented obstacles that robbed the guns of a large part of their field of fire . Attempts were made to remedy this by having an additional deck above the towers from which the sailing rigging could be operated. This, combined with the heavy towers, increased the ships' center of gravity and made them unstable. The dangerous shortcomings of this design were revealed by the HMS Captain , which capsized and sank in a moderate storm .
A significant improvement in the construction could be achieved by dispensing with the sail rigging. They built exclusively steam-powered ships , in the middle of which there was a superstructure with the funnels and one or two masts, which only carried observation platforms. The towers moved to the ends of this superstructure and from there had a clear field of fire, especially to the fore and aft.
Outwardly, the ships of this type were very similar to the later standard ships of the line , but differed considerably in their overall design. Since because of the lack barbettes the weight of the towers insufficient equivalent counteracted, this had to be installed as low as possible, so that the ships were not topp heavy. This required a very flat hull with correspondingly little freeboard . Apart from the low fire height of the guns , the sea behavior was also less than satisfactory. These ships were therefore only used in coastal waters from around 1890 (e.g. to guard port facilities or estuaries).