Kaiman-class submarine

The Kaiman class consisted of four submarines begun for the Imperial Russian Navy during the Russo-Japanese War of 1904–1905. Construction did not commence until after the war was ended and was very protracted with the boats not being completed until 1911 due to numerous defects that resulted in a legal battle between Lake and the Russian Government. The Russians impounded them in 1910 and they had to be rebuilt to remedy some of the defects. Assigned to the Baltic Fleet, they were very active during the early part of the First World War, albeit with little success. They were decommissioned in late 1916 to release their crews for newly constructed submarines.

Design and description

The Kaiman class was designed by the American submarine pioneer Simon Lake as enlarged versions of his with more torpedo tubes and a longer range that would enable to cruise of the Japanese coast. The boats displaced surfaced and submerged. They had an overall length of, a beam of, and a draft of. The Kaimans had a diving depth of. Their crew numbered 34 officers and crewmen.
For surface running, the Kaimans were powered by a pair of gasoline engines, each driving one propeller shaft. When they were rebuilt in 1910–1911, each engine had a four-cylinder section of removed which reduced their power from the demonstrated during their sea trials to. This consequently reduced their speed from the intended to. When submerged each shaft was driven by a electric motor for. The boats had a surface endurance of at and at submerged.
The main armament of the Kaiman-class boats was designed to consist of four torpedo tubes; one pair each in the bow and stern. During the rebuild two external rotating Drzewiecki drop collars were added, one on each broadside. The boats were initially designed to accommodate a deck gun, but this was removed during the rebuild.

Ships

Ship	Laid Down	Launched	Completed	Fate
	1905	November 1907	1911	Scuttled, 25 February 1918 at Reval, Estonia
	1905	1908	1911	Scuttled, 25 February 1918 at Reval, Estonia
	1905	1908	1911	Scuttled, 25 February 1918 at Reval, Estonia
	1905	27 June 1908	1911	Scuttled, 25 February 1918 at Reval, Estonia

Careers

A contract for the four submarines was placed on 1 April 1905 and they were built by the Crichton Yard in Saint Petersburg under Lake's supervision. Sea trials revealed that they had difficulties submerging on an even keel, took at least 10 minutes to submerge and could only reach a speed of 10.5 knots rather than the contractual. Lake could not correct these problems and insisted that the Russians accept the boats as they were. The Russians had already paid three-quarters of the price and refused to accept them and pay the final quarter. Lake then threatened to sell them to the Royal Swedish Navy, but the Russians decided to impound the submarines and use the unpaid monies to rebuild the Kaimans. Russian engineers had determined that many of the instability problems arose because the boats were overweight.
They were assigned to the Baltic Fleet upon commissioning and formed the Second Division of the fleet's Submarine Brigade. During 1914–1915, the boats made numerous attacks on German warships, but bad tactics and torpedo malfunctions prevented them from scoring any hits. In late 1915, the Naval Staff decided to include German merchant shipping as targets instead of just naval ships. This allowed the Kaimans to capture two small German cargo ships in October and another in August 1916. Shortly afterward, all four boats were decommissioned at Reval, Estonia, on 15 November so their crews could man the newly commissioned submarines joining the fleet. They were scuttled in Reval on 25 February 1918 to prevent their capture by the advancing German forces.