Two machines costing $304,000 that would duplicate ocean waves at proposed swimming pools in Virginia's outer suburbs are making waves with Prince William County voters.

The machines have become the focus of the debate over whether a $14.9 million recreation bond issue -- the largest bond proposal to confront Northern Virginia voters at next Tuesday's elections -- can win voter approval.

Concern over soaring interest rates and repeated attacks on the wave machines as unnedded frills have created new problems for bond supporters. James B. Spengler, director of the Prince William Country Park Authority, has pushed for the machines, assuring that they will attract enough customers to pay for themselves.

Spencler, however, admits to concern about what public attitudes over rising interest rates and inflation will do to the bond issue. "The shocking (financial) stories in the newspapers every day are not something we can control," he complained yesterday.

Bond supporters in Arlington, the only other jurisdication in the area with bond proposals on the ballot Tuesday, also voice concern about voters' worries over the economy. Voters there are being asked to approve four separate bond issues totaling $12.4 million.

Funds from the bonds call for spending $4 million on local parks, $1.7 million on regional park facilities, $4.7 million on street improvements and $1.9 million on sewers.

In Prince William County opposition to the park bonds appears stronger than in Arlington. Largely because to the wave-making machines, the Potomac News, one of Prince William's two daily newspapers, has opposed the issue, along with a scattering of politicians and tax and business groups. The machines are "completely unnecessary frill," snaps William W. Lawrence, a Republican running for the Manassas supervisor's slot.

Even his opponent, Supervisor Donald l. White, a Democrat, who voted with five other supervisors to place the bond issue before the voters, worries about some aspects of the package. "I support the concept, but I'm not sure it's a little more ambitious than it ought to be," he said.

Spengler, the parks director, says the wave-making pools should actually turn a $500,000-a-year profit for the county. A nine-year-old wave pool in Decatur, Ala., says Spengler made $314,440 after expenses in 1978.

"What we're trying to do is be very forward looking, Spengler says. "We want to have a certain percentage of our facilities generating revenues to help offset operating expenses."

Spengler said wave pool represent an improvement over conventional pools, which are constructed primarily to benefit lap swimmers. The wave pools, he said, permit body surfing and raft surfing, and at the same time can be converted to lances for swim meets.

Pools with the wave machines also tend to be more economical than conventional pools because they are shallower and use less water and chemicals, their backers say.

Most Republicans running for the Prince William Board of Supervisors are campaigning against the bonds and the incumbent Democrats generally say the question is up to the voters.

Heaviest support for the bonds is in the more populous eastern part of the county. "For years and years, the county has been growing at a rapid rate, and one of the agencies that has not kept pace has been the park authority," said Terrence Spellane, president of the Dale City Civic Association.

Spellance rejects suggestions that the park authority could quickly repackage a trimmed-down issue if the bonds fail Tuesday. "If it doesn't pass, you won't get another shot for five to six year," he said.

It has been 11 years since a park bond referendom was sent to Prince William voters. During that period the county has grown at a rapid rate with the lack of parks a frequent political issue. "For the last five years, the issue has been that there is not enough athletic facilities and recreation for the kids," Spengler said.

Much of the $14.9 million bond money would go for new athletic fields -- for football, softball, baseball and soccer. There would also be gymnasiums, miniature golf courses, tennis courts, and those wave-making pools. gSome of the money is targeted for hiking trails and nature areas.

The bonds would add about $33 annually to the average homeowner's real estate tax bill, according to county figures. The burden would decrease over the expected 20-year-life of the debt.

In Arlington, park bond supporters say funds are needed to enhance the corridor between Rosslyn and Ballston and to preserve some of the last vestiges of open space elsewhere.

"We don't want another Rosslyn," said Judy Sibert of the Arlington League of Women Voters which has indorsed of the spending. "We want the area (Rosslyn-Ballston corridor) to be an attractive place to work in."

The opposition includes a group called Committee of concerned Citizens, which so far seems to have mounted only one sustained effort -- a mailing last week -- and the Arlington Chamber of Commerce. Norman W. Worthington, executive vice-president of the Chamber, said his group believes "there is no shortage of park land in Arlington." The Chamber has supported the $1.7 million regional park bonds, but considers the local $4 million park bond package too costly.

Neither the sewer construction nor the $4.5 million street bonds have aroused much controversy.