Lexington's extreme pursuit of scouting speed

The American scouting concept began with a 35-knot requirement that was ambitious even for contemporary destroyers and cruisers. Propulsion demand rose so steeply with speed that a target around 32 knots would have made an enormous difference to the design. The Lexington studies nevertheless pursued the higher speed with machinery arrangements such as a second row of boilers several decks above the first, placing machinery spaces well above the waterline. The requirement was eventually reduced by a couple of knots, but only after extensive effort to approach the original target. The Pacific's distances and room for manoeuvre gave fast reconnaissance ships a clear operational role. That requirement still had to be weighed against the machinery and protection compromises involved in achieving such speed.