At average ages of about 43 and 23 years, respectively, the high-endurance cutters and patrol boats are three years past the ends of their estimated service lives, according a report by the General Accountability Office, the investigative arm of Congress, released this summer.

The mid-sized cutters also are fast nearing the ends of their estimated service lives.

In fiscal year 2011, the fleet fell about 40,000 hours, or 23 percent, short of its benchmark for operating without major equipment problems, the GAO said.

The number of hours the biggest cutters spent on drug interdiction fell by almost two-thirds from fiscal years 2007 to 2010, mostly because of equipment breakdowns.

The fleet “is in overall poor condition and is generally declining,” the GAO said.

The shortfall in operating hours would “likely result in more cocaine and illegal migrants reaching U.S. shores and a decreased capability to protect U.S. waters and fish stocks from the encroachment of foreign fishing vessels,” it said.

Representative Frank LoBiondo, a New Jersey Republican and head of a House subcommittee on the Coast Guard and marine transport, told a hearing last month the service was caught in a “death spiral” of too few ships and too many missions.

Rear Admiral Ronald Rabago, the head of engineering, responded that individual ships were meeting performance goals, but added: “It is true that in the aggregate our fleet is not achieving those objectives, those targets.”

JUGGLING PRIORITIES