The class used water-tube and cylindrical boilers feeding triple-expansion engines for 23 knots and a long cruising radius. Turbines were considered, but the technology was judged too immature to justify the added cost and risk. A turbine installation might have raised speed to roughly 25 knots, yet it could also have added about £300,000 and reduced endurance without an oil-fired plant. The comparison illustrates the practical trade between headline speed, endurance, fuel arrangements, and reliable procurement.
Notable Point · 11:52-13:03
Why proven machinery won over turbines
The choice of triple-expansion engines balanced a 23-knot top speed and long range against the cost and technical risk of early turbine machinery.