Other than an engine overhaul, what is the most strenuous dry-dock maintenance procedure?
Short answerMajor keel repair is a leading candidate because it addresses damage to the hull's primary structure.
NotesBarrel replacement changes weight distribution and requires heavy lifts, but can sometimes be completed alongside a pier with a suitable crane. Wartime barrel changes could be done extremely quickly and did not always require dry dock at all. Keel damage is more fundamental because grounding, storms, and even machinery loads can distort the ship's primary structure. HMS Belfast is cited as a reminder that major keel work belongs within the practical maintenance burden of warships.