Image of a medium landing ship, from the CBO’s recent report. (CBO)

WASHINGTON — The Navy’s upcoming medium landing ship could cost billions more than the service plans, according to a new report by the Congressional Budget Office.

The CBO believes an 18-ship fleet would cost between $6.2 billion and $7.8 billion in 2024 (inflation-adjusted) dollars, or $340 million to $430 million per ship. That’s a stark contrast to Navy figures, which, according to the CBO, has an 18-ship program at $2.6 billion total, or about $150 million per ship.

Even using the more optimistic CBO figure, the gap between the two totals is eyewatering: $3.6 billion more, or a 138 percent overrun.

However, the figures come with a very large caveat: CBO admits that there are a number of factors that could shift things up or down. Among them are design decisions (ships designed to commercial standards are cheaper than those of military standards) and quantity of buy (the Navy has discussed extending the buy up to 35 ships, which would impact both the per unit and overall costs significantly.)

The medium landing ship is part of the US Marine Corps Force Design 2030 effort, which has the Corps shifting away from some traditional missions and towards capabilities that supporters say will be most relevant in the Pacific. The new ship is intended to transport Marine littoral regiments in and around a conflict, with a focus on a potential conflict with China.

The program has actual funding laid out in the fiscal 2025 request: One ship purchased in FY25 and FY26, followed by two ships per year throughout the current future years defense program ending in FY29. The requested funding for FY25 is $268 million with future years’ requests gradually ramping up to above $300 million in FY28 and FY29.

The characteristics being discussed by service leaders put the length of the ship between 200 to 400 feet, with a speed of 14 knots and a range of 3,500 nautical miles. The ship would require a crew of 70, and is supposed to be able to transit 50 marines plus equipment, with a 20 year service life.

The Marine Corps began the formal request for soliciting proposals earlier this year and will spend much of 2024 receiving and evaluating potential offers. A contract to the chosen shipbuilder is anticipated for award in March 2025 and the first ship will be due for delivery roughly four years later in February 2029, according to the new budget documents.

According to OMB, the Navy awarded early contracts to five contractors for preliminary work on the design: “Austal Shipbuilding, Bollinger Shipbuilding, Fincantieri Marinette Marine, VT Halter Marine (now owned by Bollinger and renamed Bollinger Mississippi), and TAI Engineers.”

A request for comment from the Navy was not returned by press time.

Justin Katz contributed to this report.