Big-gun fighting knowledge faded over decades

How quickly did navies lose their institutional knowledge of fighting with big guns after the Second World War?

More slowly than might be expected: battleships and experienced officers remained in service, so the estimated decline takes roughly thirty to forty years.

Battleships remained active after 1945, while junior officers with wartime experience continued rising through naval careers. Big-gun knowledge therefore seems to have eroded several decades later. A weapon can retire before its professional culture disappears.