WASHINGTON, Oct.18 (Xinhua) -- The U.S. Navy plans to purchase 245 combat ships and 56 support ships between now and 2048, according to a report released by the Congressional Budget Office (CBO) on Thursday.

The report, an analysis of a Navy budget plan submitted in February this year, showed that the purchase plan would not allow the Navy to reach its targeted 355 fleet size at anytime in the next 30 years, unless the Navy significantly lengthens the service life of current warships.

Should the the U.S. Navy fully implement its previous announcement to extend the service life of its destroyers from 35 years or 40 years to 45 years and the life of seven attack submarines from 33 to 43 years, the Navy may reach its target fleet size in 2034, but not for all individual ship types, according to the analytical report.

Based on what the Navy proposed, the CBO estimates that the annual purchase and ship maintenance costs would average 28.9 billion U.S. dollars per year.

The report also revealed that under the Trump administration the U.S. Navy has made bold plans to expand its fleet, seeking to purchase 47 more ships in a 30-year time span, compared with a fiscal year 2017 plan drafted under the Obama administration.

The purchase is expected to increase all types of ship except for small surface combatants and ballistic missile submarines.

The 2019 plan asked for 16 more attack submarines, 10 more large surface combatant ships, five more large payload submarines and five more amphibious warfare ships, compared with the 2017 plan.

The report also outlined the pace at which the Navy plans to purchase new ships. The Navy hopes to add to its fleet one aircraft carrier every five years, two attack submarines every year, five large surface combatant ships every two years and two small surface combatant ships every year starting in 2022.