The Bramble-class gunboat was a type of warship used by the Royal Navy between the 1890s and the 1920s. The four ships of this class were notable as the final development of the Victorian gunboat tradition, and for being one of the last classes of warship designed to travel under sail. One of them, HMS Thistle, retained a functional sailing rig into the mid-1920s.
Design
The four Bramble-class gunboats were designed to protect the far-flung outposts of Great Britain's colonial empire. At 180 feet long and 33 feet in beam, with a draft of just 8 feet and a displacement of only 710 tons, they were the smallest seagoing vessels built for the Royal Navy in the 1890s. They were also among the cheapest, built at a cost of just over £50,000 each, less than 5% of the cost of a contemporary battleship.
Limited steaming range and the continuing need for sails
The small dimensions and shallow draught of the Bramble class were designed to facilitate navigation on the complex coastlines and great rivers of Africa, South Asia and the Far East. The drawback this imposed was a limited fuel supply. The type entered service with a standard bunkerage of just 50 tons of coal. For Thistle, considered one of the better-performing ships of the class, this would only provide two and a half days' movement at her sustained cruising speed of 11.5 knots, and full-speed runs used nearly twice the quantity of coal over any given length of time. In practice, storage was found for 145 tons of coal, but this was still sufficient for only one week of cruising.
The Bramble class were therefore designed with a sailing rig to supplement their engines. This was still widely accepted in the 1890s as a necessity for long-range warships, which would not always have reliable access to coaling stations. Modern ships which retained a full sailing rig in the 1890s included the Russian armoured cruiser Rurik, the six German Bussard-class light cruisers, the United States Navy's Annapolis-class gunboats, and the Royal Navy's own Condor-class and Cadmus-class sloops.
However, the use of sails was not universally accepted: the armoured battleships of the great powers had become so large and heavy that they had abandoned the remnants of sailing rig in the mid-1880s, and modernizers argued that any sailing warship was automatically obsolete.
Whereas most cruisers of the 1890s adopted a three-masted barque or barquentine rig combining a strong emphasis on fore-and-aft sails with a partial square rig, the Bramble class differed by being designed as two-masted ships, and in 1911, the authoritative partnership of Sir Philip Watts and John Harper Narbeth noted that they only used a "reduced" fore-and-aft sailplan. Thus rigged, they somewhat resembled the much larger contemporary Royal Navy protected cruisers such as the Astrea class and Eclipse class, which had two "military masts", principally used for signal halyards, lookout positions and fighting tops, but designed to set auxiliary fore-and-aft sails in an emergency. On the other hand, HMS Thistle used some square sails, and there appears to be no clear evidence what their designed sailplan was (an original brig or brigantine sailplan like the earlier HMS Temeraire cannot be ruled out).
Other features
In order to further reduce the logistical requirements (and construction costs) of the new gunboats, a number of other decisions were taken which seemed almost willfully anachronistic. They had copper sheathing to protect their hulls against fouling in tropical seas. With minimal machinery, old-fashioned human strength on the capstan was required to raise the anchors, and a functional ship's wheel was provided to turn the rudder. All lighting came from candles rather than light bulbs. Only one of the four ship's boats was equipped with an engine, the rest being powered by sails and oars. Some of the guns were even mounted internally behind gunports.
In some important respects, however the gunboats were thoroughly up-to-date. Their armament of two 4-inch guns, four 12-pounders and four or more heavy-calibre Maxim guns was modern, and the firepower it provided was comparable to that of comparable ships from rival navies, such as the German gunboat SMS Panther. Each ship's triple-expansion steam engine was capable of 13.5 knots, only slightly slower than contemporary battleships and cruisers, and their hulls were built of steel, exploiting metallurgical advances of the 1880s, rather than using older wrought iron or composite construction techniques.