NATIONAL HARBOR, Md.—The Navy in March began underwater testing of its first extra-large unmanned underwater vehicle (XLUUV), which will help reduce risk on the first five prototype vessels, a Navy official said on Tuesday.

“Initial results are good,” Capt. Scott Searles, program manager of the Unmanned Maritime Systems Program Office within the Program Executive Office for Unmanned and Small Combatants, said during the Navy League’s Sea-Air-Space conference here. The reason behind having the XLEO vehicles is the “test, fix, test” that will lead to “more discovery” and inform any changes that will have to be made when the five Orca prototypes are assembled as well as provide lessons learned, he said.

Still, with XLEO in the water, the program is “picking up steam and speed,” Searles said.

Searles said the timeline for the program is largely unchanged with the plan to begin forward deploying the XLUUV in fiscal year 2026.

Boeing [BA] is the prime contractor for the program and teammate HII [HII] will build the hulls of the 50-foot plus diesel-electric submarines that will support mine countermeasures, anti-submarine warfare, and intelligence, surveillance and reconnaissance missions. Searles said that about 90 percent of the material for the five prototype subs has been delivered with supply chain issues hampering delivery of the remaining parts and materials, creating a roughly 12-week delay in the program.

The XLUUV program is about three years behind schedule and has experienced significant cost overruns, according to a Government Accountability Office (GAO) report in September 2022. The congressional auditing agency found poor business planning, including no requirement for Boeing to demonstrate its readiness to build the Orca to the Navy’s configuration (

Defense Daily, Sept. 29, 2022).

The main technology challenges are in the past, Searles said.

The Navy last year said it would implement the GAO’s recommendations. Searles pointed out that the 85-ton Orca is a “first of its kind” program that requires time to “work through some of the technological challenges.” However, he added that, “We feel like we’re at an inflection point where we’ve got all of those technical challenges solved.”