When will the Navy — all the services, really — learn that it takes a lot more than wishing when it comes to building multimillion-dollar weapon systems?

The F-35 Lightning II Joint Strike Fighter and the nuclear aircraft carrier USS Gerald R. Ford have gotten attention because of billion-dollar overruns generated when the Air Force and the Navy tried to begin production before the design, development and testing of key elements were completed.

The same thing may be happening at the individual weapon systems level, where less attention is paid because fewer dollars are spent — though we’re still talking tens and hundreds of millions.

Take, for example, a new Defense Department inspector general report, released Wednesday, that spells out problems with the Navy’s Organic Airborne and Surface Influence Sweep (OASIS) system.

I’d never heard of it, either.

When OASIS was funded in 2002, the Navy described it as a system that would provide a “minesweeping capability to effectively neutralize [the] threat [from] sea mines in operating areas where mine hunting is not possible” because mines are buried or there is clutter on the sea bottom.

OASIS is a 10-foot-long cylinder, roughly 16 inches in diameter, that is towed in the water by a Navy MH-60S helicopter, which is to be carried on the new Littoral Combat Ship.

The cylinder puts out bubbles that simulate the acoustics of a ship while another of its systems creates magnetic signatures of U.S. ships. The two together are supposed to cause mines at any depth to explode. Think of Iranian mines in the Strait of Hormuz, for instance.

Sounds interesting, but will it work?

The OASIS program was funded with an initial operating capability set for late 2005. Since then, according to the inspector general’s report, it has “experienced a significant schedule delay and cost growth.”

An inspector general’s report from April found management problems when the OASIS contractor, ITT Exelis, moved in 2008 from New York to Florida. The Defense Management Contract Agency (DMCA), in a bureaucratic mix-up, did not provide the usual contract-monitoring backup to the program manager. One result of the lack of a DMCA support team for three years was a $10.4 million cost increase by late 2011 and a new DMCA team finding that the schedule and technical areas “were all high risk.”

The research, development, test and evaluation phase for OASIS was originally estimated to cost $55.1 million and take three years to begin production. That phase is now expected to cost $135.4 million and be finished in late 2013, 11 years after it started.

According to the inspector general’s report last week, there have been design changes, corrosion of a key electrode, towing issues and electrical-related problems.

In addition, the report said, the Navy “did not finish defining the capability requirements” for OASIS, yet “planned to enter the low-rate initial production . . . without completing all testing.”

The report focused on shock testing, which would measure the system’s ability to keep working after it caused a mine explosion and was hit by the resulting shock wave. This testing has not been done, although “a contractor’s analysis showed the OASIS would not work after sustaining a shock wave of 65 percent of the shock capability requirement” established in 2001. The Navy has not funded any new study “to determine a defensible and realistic shock wave requirement,” according to the report.

The shock testing was delayed, the report said, because the program manager was concerned that it might destroy or disable the test OASIS models.

Meanwhile, the Navy is studying whether redesign costs would be less than buying more spares of OASIS’s shock-vulnerable components, one of which has “an estimated . . . cost of $750,000,” according to the report. That is about 20 percent of the cost of one OASIS unit.

The system has also not undergone an integrated test with the MH-60S helicopter; that would involve towing it over an instrumented test field containing inert mines. Nor has it completed a reliability growth plan to make sure that certain components can meet the system requirements when all testing is completed.

As of now, the Navy hopes to start low-rate production with four OASIS units for $15 million and eventually buy 38 more for $140.6 million, or $3.7 million each. Developing and procuring OASIS has become a $290.5 million program.

The report argues that the initial units may require costly retrofits and may not meet test requirements before a decision for full-rate production is made — now scheduled for 2015.

The inspector general recommended that the Navy “assess whether the OASIS program, with reduced shock resistance capacity, is worth the additional investment required to continue to completion.”

That is not so unusual. In 2010, the Navy eliminated funding for another system because it “did not demonstrate the ability to neutralize mines when installed in the MH-60S helicopter,” according to the report.

The Defense Department lists the OASIS program as an “Acquisition Category II major defense system,” which means its overall procurement costs could exceed $600 million. These programs don’t get the attention given to Category I, in which procurement costs begin at $2.2 billion.

Perhaps they should.