Forced draught raised the class to about 20,000 indicated horsepower and 22 knots. The Orlando comparison makes the scale of the change clear: its machinery reached roughly 8,500 indicated horsepower and about 18 knots under forced draught. Blake and Blenheim used two triple-expansion sets on each shaft, dividing the work between economical cruising and high-speed machinery. That specialization anticipated later turbine installations that paired cruising and high-speed sets. Six double-ended cylindrical boilers, rather than Orlando's four, helped make speed a defining advantage of the protected design over its nominally more heavily armoured predecessor.
Notable Point · 19:36-21:45
Twenty-two knots from specialized cruising and speed engines
The Blakes more than doubled the Orlando's indicated horsepower and used separate cruising and high-speed engine arrangements.