Naval History and Heritage Command
A forest of masts, primarily cages, stretch skyward from the Philadelphia Navy Yard Reserve Basin on 22 October 1919, with at least six battleships and 14 cages visible. From left are the Iowa, Massachusetts, Indiana, Kearsarge, Kentucky, and Maine (Battleships Nos. 4, 2, 1, 5, 6, and 10, respectively).
Seagoing examples of hyperboloids of revolution, cage masts were lightweight, strong, and easy to construct.
The battleship Massachusetts displays a conical foremast—precursor to the cage mast—with its spotting (upper level) and fighting tops. The Navy was concerned that one well-placed shot could cause the whole mast to collapse. The Massachusetts would later receive a cage mainmast.
The first cage mast is shown stepped on the quarterdeck of the Florida (Monitor No. 9) in May 1908, just before gunnery trials. The mast was mounted at the unusual angle to compound test conditions.
Taken on 14 September 1908, this photograph is believed to show the first cage mast mounted on a battleship. The ship is the Idaho (Battleship No. 24) five months after her commissioning. The cage, pictured shortly after it was stepped, is also believed to be the original used in the monitor Florida tests.
The Massachusetts (Battleship No. 2), an Indiana-class ship commissioned in 1896, received a cage stepped at the main in 1909. She retained this configuration when she was scuttled off the coast of Pensacola, Florida, in 1921.
The lead ship of her class, the Iowa (Battleship No. 4) is shown during World War I. She also received only one cage mast stepped at the main. This was her configuration when, renamed Coast Battleship No. 4, she was sunk during gunnery trials in the Gulf of Panama on 21 March 1923. She was the first radio-controlled target ship to be used in fleet exercises.
An Illinois-class pre-dreadnought, the Wisconsin (Battleship No. 9) had cages stepped at both the fore and main by 1911.
The lead ship of her class, the Mississippi (Battleship No. 23) received her first cage, stepped at the main, in 1909. The next year she received one stepped at the fore.
Also the lead ship of her class, the Colorado (BB-45) shows her commissioning guise in this photo taken around 1942. The cage masts have been strengthened to support the heavy multilevel gunnery tops. Note that the foremast is virtually a stub supported by a tower structure; the latter would be common in later-build U.S. battleships.
The Montana (Armored Cruiser No. 13), shown on 4 May 1912, is representative of the two cruiser classes that received cage masts. The ten ships of the Pennsylvania (Armored Cruiser No. 4) and Tennessee (Armored Cruiser No. 10) classes were the only U.S. ships other than battleships to receive cage masts. All were stepped at the fore.
The Arizona (Battleship No. 39) has just passed beneath the Brooklyn Bridge on her way up the East River to the Brooklyn Navy Yard shortly after her commissioning in October 1916. The bridge was the determining factor for the height of not only cage masts but all masts of ships that needed access to the navy yard. Barely discernable are pine “topping” trees atop each mast, symbolic of completion.
The Maryland (BB-46) is pictured in her late-war configuration. A simple pole has replaced the main, but she retains her foremast cage, which she would keep to her scrapping in July 1959. The Maryland and Colorado (BB-45) were the last two U.S. ships with cage masts.
A comparison of some cages and one non-cage. From left: The first mast is the classic U.S. hyperboloid design as stepped on the Massachusetts in 1911. Next is the last of the U.S. cages, this on Colorado in 1942. These heavily constructed cages carried much larger and heavier fire control towers. Because the Argentinean Rivadavia, pictured in 1913, was American-built, she carried the authentic U.S. cage design at her fore. Last, the cage of the Russian Andrei Pervozvanny, shown in 1912, was not of hyperboloid design.
Hyperboloid masts were almost unique to the U.S. Navy, with only six foreign navy battleships mounting them; however, all of those have caveats: two carried ersatz cages, two were American-built ships, and the other two were former U.S. Navy battleships.
In 1906, the Imperial Russian Navy launched two sisters, the Andrei Pervozvanny (pictured) and Imperator Pavel I, which were commissioned in 1911. While their original 1903 design featured military masts, the 1904 Battle of the Yellow Sea prompted the Naval Technical Committee to rethink the design. A 12-inch shell from the Japanese battleship Asahi had severely damaged the Tsesarevich’s foremast, threatening its collapse. Had that happened, the committee feared it would have disabled the secondary guns around it. The Russians chose to replace the masts with a design based on the American cages, but they had a problem. There was not enough deck space to accommodate the masts’ base rings, thus the designers used a smaller, oval, base ring and a conical rather than hyperboloid form. The resulting masts, installed in 1910, immediately proved to be unstable and vibration prone.
Interestingly, the captains of the two ships had diametrically opposed views of the masts. That of Andrei Pervozvanny vigorously defended them, while his opposite number offered to replace them in three days. By mid-1914, however, they had been largely replaced with only portions of their base remaining.
The Argentine battleship Rivadavia enters the Brooklyn Navy Yard drydock on 6 August 1913, a year before her commissioning. In 1911, two American-built battleships were launched in the United States and four years later commissioned for and by the Argentine Navy. These where the only dreadnoughts built by the United States for export. The Rivadavia, built by the Fore River Shipyard, and Moreno, by New York Shipbuilding Corporation, carried purely American cages at the fore but simple poles, later converted to tripods, at the main. They have the distinction of being the last ships to carry full hyperboloid cages when they were scrapped in 1959 and 1957, respectively.
The last two ships to carry the cages in a foreign navy were the U.S. pre-dreadnoughts Mississippi (Battleship No. 23) and Idaho (Battleship No. 24). By the time the sisters were sold to the Hellenic (Greek) Navy in 1914 and renamed the Kilkis and Lemnos, respectively, they had cages at their fore and main. Top: The Mississippi (Kilkis) is pictured before her transfer to Greek Navy. Bottom: The Lemnos rests at anchor at Constantinople in 1919.
The Kilkis (foreground) and Lemnos are pictured after being sunk during German aerial attack at Salamis Naval Base on 23 April 1941. Their cages are readily visible and seemingly undamaged.
Russia considered cage masts for four Gangut-class battleships, but based on the experience with the Andrei Pervozvannys, built them with poles. Meanwhile, the Kaiserliche Marine (Imperial German Navy) designed SMS Von der Tann with them in 1907, but also opted for poles.
Beginning in 1909, Fort Drum was constructed on an island in the entrance to Manila Bay. It was for all intents and purposes a concrete battleship, mounting two superposed turrets each with a pair of 14-inch guns along with four 6-inch guns in armored casemates. Providing fire direction control was a station mounted atop a hyperboloid cage mast.
The Royal Navy investigated cage masts, but opted for tripod mountings, as seen here with both the fore and main on HMS Dreadnought (1906). As the fire control tops became heavier, the United States opted for tripods in the 1930s reconstructions of its more recent battleships.
The intricacy of the cage mast as used by the U.S. Navy belies its basic simple construction. This mast and the accompanying kite balloon are attached to an unidentified battleship in 1919.
The base of Michigan’s (Battleship No. 27) foremast in December 1911 shows some interesting features. Atop the deckhouse, amid the jungle of rods, pillars, and posts is a binnacle in the center and a bell off to the right behind the ladder; the searchlight platform is above all.
The view looking up the Michigan’s foremast shows details of stands and reinforcing hoops at various levels.
The heavy gunnery top of the Colorado (Battleship No. 45)’s mainmast required a reinforced and heavier hyperboloid structure for support. Visible in the drydock is the SS Leviathan, c.1930.
The relatively lightweight construction of the Virginia (Battleship No. 13)’s mainmast stands in contrast to that of Colorado. Note the mesh platforms within the mast and the ladders projecting up through it, leading to the circular fire control platform at the top.
