How reserve time affects a destroyer's hull life

How much service life does a warship preserve while laid up in reserve, using HMS Daring's long refit and layup as an example?

About six months of active hull life per reserve year is a useful average, though the estimate ranges from three to nine months depending on layup and maintenance.

Calendar age and active-service wear are not equivalent, so HMS Daring's nine-year refit and layup would not extend its usable life by nine years. The discussion recalls Royal Navy design assumptions of roughly 30 years, with an added allowance described as about 40 years of heavy-duty life; these figures are tentative. A year in reserve might preserve only three months of active hull life in poor conditions, or as much as nine months with better layup and maintenance. Six months is offered as a working average. On that basis, nine years laid up would consume about four and a half years of service life. Reserve status slows wear while still requiring maintenance.