The machinery study considered engines forward of boilers, the reverse arrangement, and turbo-electric drive before settling on a compact two-shaft plant. As calculations matured, the estimated weight repeatedly rose above the desired 2,000 tons. Designers considered higher propeller revolutions, lighter fittings, aluminium components, reduced spares, and shore storage of lifting gear and fuel-heating equipment. Each proposal carried an operational cost, such as reduced propeller efficiency or limits on usable fuel oil, so the board did not accept every saving. Nelson's completed machinery weighed about 2,150 tons, which remained unusually low for a 45,000-shaft-horsepower battleship plant.
Chapter · 1:57:20-2:01:14
How Nelson's machinery was squeezed under the treaty limit
Designers compared machinery layouts, shafts, revolutions, materials, and even equipment stored ashore in an effort to hold Nelson's propulsion plant near two thousand tons.