CASTINE — On a Maine Maritime Academy vessel floating just off Dyce Head in Castine, Habib Dagher stood in front of his 65-foot-tall, yellow-and-white brainchild, VolturnUS — the first grid-connected offshore wind turbine in the Americas.

“Today, we can declare VolturnUS mission accomplished,” he shouted to a group of about 40 legislators, federal and university officials crowded onto The Capt. Susan J. Clark for a Friday afternoon ceremony.

VolturnUS, a 1:8-scale prototype for the huge 6-megawatt turbines that could one day power an offshore wind energy industry in Maine, has been resting on its proving grounds for the past year, withstanding the toughest tests Maine weather had to offer, including 18 “severe storms.”

Dagher, the director of UMaine’s Advanced Structures and Composites Center, is preparing to turn his attention to the next task at hand: designing and building the full-scale, 450-foot-rotor-diameter versions.

The effort to install two 6-megawatt floating wind turbines off Monhegan Island hit a stumbling block in May when the U.S. Department of Energy announced that UMaine would get a smaller-than-hoped-for grant to move the project forward. Three other wind projects in the nation were offered full funding up to $47 million. UMaine hoped to be among them but instead was selected as an alternate, receiving a significantly smaller grant to help the university complete the design and engineering work needed to build a full-scale turbine.

The Department of Energy had $168 million in funding to work with when it distributed awards after a competitive application and proving process.

During Friday’s carefully orchestrated boat ride to VolturnUS, Dagher and Department of Energy Assistant Secretary for Energy Efficiency and Renewable Energy David Danielson signed a $3.8 million cooperative research agreement, which will have the university working hand-in-hand with Department of Energy officials to iron out the design and logistics of the future 520-foot-tall turbines.

But the smaller grant award doesn’t mean the Department of Energy doesn’t see significant potential in UMaine’s technology, Danielson said after the event

“This is an incredibly innovative project,” he said. “We absolutely see the promise in this technology and want it to go full-scale.”

Otherwise, he wouldn’t have been sent all the way to Maine from Washington, D.C., to celebrate the conclusion of a successful yearlong test of the system and wouldn’t be signing an agreement to help the university push it through to its next phase, Danielson added.

“They believe in this project,” Dagher said. “They believe in this technology.”

Dagher stressed that UMaine is still in the running for a significantly larger federal award. If more funding becomes available through the budgeting process or another recipient fails to meet the terms of their agreement with the Department of Energy, the department could dole out that money to any candidates that didn’t receive the full amount, according to Danielson.

Friday’s event drew Rep. Mike Michaud and Sen. Susan Collins, who were credited for their efforts on a federal level to advance the project. The University of Maine, Maine Maritime Academy, Cianbro Corp. and others also were represented. The British embassy also sent two delegates, who asked to attend and meet with Dagher about the university’s technology. Great Britain, which is making a concerted push toward becoming a global leader in offshore wind energy production, is looking into wind systems that could one day be used off its wind-swept coastline, Dagher said.

The 20-kilowatt VolturnUS prototype not only survived but excelled during the past year of harsh testing, Dagher said. The turbine sustained 18 major weather events ranging in severity from 50-year storms to 500-year storms, which were measured on the 1:8 scale to simulate how weather conditions would affect the full-scale version of the turbine. It sent electricity to shore by an underwater cable. Though the turbine was created primarily to test the stability and viability of the VolturnUS design, rather than to produce energy, Dagher said, it met expectations in terms of energy production efficiency.

In the one 500-year-equivalent storm — meaning a weather event so severe that odds are it will only happen once every 500 years — the 1:8 VolturnUS faced off against nearly 9-foot waves, which would be the equivalent to 70-foot waves on the full-size version. In spite of the swell, the turbine tipped just 7 degrees off vertical, which was better than models predicted.

The 1:8-scale turbine, outfitted with some 70 sensors to measure everything from wave height to currents, is expected to be pulled from the waters off Castine in November. Dagher said it likely will be put on display somewhere, a showcase to the fact that Maine was home to a first-of-its-kind renewable energy technology.

By 2017 or 2018, Dagher hopes to have two full-size turbines off Monhegan Island for further testing before stretching the technology into commercial use. Significant legwork still is required to secure financing — somewhere between $100 million and $150 million — and iron out the engineering and logistics of the project, he said.

The long-term vision is the construction of a 500-megawatt offshore wind farm in the Gulf of Maine, 20 miles off the coast. The goal is to achieve wind-generated electricity at 10 cents per kilowatt-hour by the mid-2020s, which would be competitive with other forms of electricity generation.