One ship, Bristol, had Brown-Curtis turbines driving two propeller shafts, while the remaining three ships used Parsons turbines driving four shafts.
The Bristols were protected cruisers, with an armoured deck providing protection for the ships' vitals.
The Town class was a group of twenty-one light cruisers built for the Royal Navy (RN) and Royal Australian Navy (RAN).
Torpedo armament was increased, with two 21-inch (533 mm) submerged tubes (with seven torpedoes carried), while the ships' armament was completed by four 3-pounder saluting guns.
The class saw a number of alterations during the war, including the addition of a single 3 in (76 mm) AA gun in 1915, while the surviving ships were fitted with director control equipment for the ships' guns on a new tripod foremast.
The five British-built ships commissioned between 19, while Brisbane, the Australian-built ship was laid down in 1913 and completed in 1916.
The major difference between the Chathams and the earlier Towns was a revised armour scheme.
with the officers accommodated in the forward part of the ship, rather than aft as per tradition, following the instructions of Admiral Fisher to improve fighting efficiency.
This arrangement was unpopular, however, as it was preferred to keep officer's and other ranks accommodation separate for disciplinary reasons, while the Bristol class were very cramped, with only 12.5 square feet (1.16 m They were 453 feet (138.1 m) long overall, with a beam of 48 feet 6 inches (14.78 m) and a draught of 15 feet 6 inches (4.7 m).
In 1917, Yarmouth was the first light cruiser to be able to operate aircraft, being fitted with a ramp above the conning tower and forecastle gun to allow a Sopwith Pup to be launched from the ship, although the aircraft could not land back on it so the pilot would have to ditch into the sea if it was not possible to reach land.
of six ships, three for the Royal Navy and three for Australia (of which one was to be built in Australia) were ordered under the 1910–1911 Programme.
While main armament again consisted of eight 6 in guns in single mountings, a new gun, the BL 6 inch Mk XII was used.
This was shorter and lighter than the Mk XI guns used in earlier ships, and while range was slightly less (14,000 yards (13,000 m) compared to 14,600 yards (13,400 m) Wartime changes were similar to those made to the Weymouths, with a 3-inch anti-aircraft gun fitted during 1915 and director control with its associated tripod mast fitted later in the war.
While the earlier ships were protected cruisers, depending on an armoured deck deep within the ship to protect machinery and magazines, the Chathams relied on a vertical belt of armour.