Brazil's Bahia class: turbines reshape the scout cruiser

The Bahia class borrowed the Adventure pattern but grew to roughly 3,100 tons and used Parsons turbines fed by ten Yarrow boilers instead of triple-expansion machinery. Designed for 26.5 knots, the ships reached 27 knots on trials and could still make 25 knots fully loaded. They carried up to 650 tons of coal and had a range of about 3,500 nautical miles at 10 knots. Protection consisted of a 19-millimetre deck and a 76-millimetre conning tower, with no belt listed. Ten 120-millimetre, or 4.7-inch, guns, six 47-millimetre guns and two 18-inch torpedo tubes supplied much more firepower than Adventure's original battery. Only Bahia and Rio Grande do Sul were built after a third ship was cancelled; the pair were the world's fastest cruisers when commissioned, were modernised in the 1920s and remained in service until 1948. Their two funnels, compared with Adventure's four, make the effect of turbines and the slightly larger hull immediately visible.