Why fleet availability blocked Hood's reconstruction

Would a wartime-constrained Hood refit mainly replace her weapons?

Weapons could be changed relatively quickly; the real reconstruction required years to replace turbines and machinery, and Britain could not spare Hood from operational commitments for that long.

A major Hood reconstruction meant stripping the ship and renewing machinery, not merely adding dual-purpose guns and anti-aircraft weapons. Armament changes could be completed in months, while replacing turbines and rebuilding internal systems would remove the ship for years. Britain possessed the dockyard skill and material to do that work. Treaty-era fleet reductions left too few capital ships to cover Hood's absence while meeting worldwide commitments. From 1934 the need to deter Italy in the Mediterranean tightened that availability problem further, making operational coverage rather than technical feasibility the decisive bottleneck.