ESCONDIDO —— Backers of a quixotic proposal to build the region's next commercial airport offshore got together Thursday to show why they think their idea will float.

In a low-tech demonstration, they placed a crude airport mockup in the middle of a large wave tank at Escondido's Offshore Model Basin to demonstrate what they maintain is the viability of their proposal.

The bare-bones model did indeed float when a small wave was introduced, but it also seemed to pitch up and down.

Undeterred by the wavering model, Encinitas attorney and floating airport backer Adam Englund showed off his vision.

"We're moving forward with this because we think San Diego is can-do country," said Englund, who earlier this year pitched the plan to the San Diego County Regional Airport Authority.

"An airport in the ocean would be infinitely expandable and we would create a new industry of ocean development."

The airport authority has until April to come up with a recommendation on whether to expand downtown San Diego's venerable Lindbergh Field or build a new airport.

Lindbergh, a site near Campo and a site just east of the county line in Imperial County remain on the authority's list. A site near Borrego Springs is also officially still on the list but not considered viable because of its distance and limited highway accessibility.

Five military sites are also on the list, but none of those are considered viable either because each is an active military base.

The notion of an offshore, floating airport in the Pacific waters is not new to the airport search. Two years ago, a group called Float Inc. brought a similar idea forward but saw it dismissed because of engineering challenges, constantly changing ocean conditions and frequent wind and fog.

Englund said that after his brief presentation to the airport authority in June, he decided the best course is to take the idea directly to the voters. Within a month, he said supporters will begin circulating a petition for a ballot measure that would appear on the same November 2006 ballot as the airport authority's recommendation.

His group needs to collect about 60,000 signatures from registered voters to qualify the measure.

One of those working with Englund is Craig Lang, a marine engineer and naval architect, who constructed the model used in Thursday's demonstration.

"This is only a technical exercise to explain the needs and qualifications," Lang said. "A floating airport would be a structure with ample room for innumerable facilities."

Another supporter, Duncan Fane, said he believes expansion of Lindbergh to add a second runway is impractical because of the high number of homes and businesses that it would displace.

There are no floating airports in the world. A proposed offshore airport in Tokyo was abandoned when funding failed to materialize.

Asked why he continues to push the idea, Englund said he has been captivated with the idea since he was a child.

"For me, it's just like the Blues Brothers," he said. "I've always looked for the right time and the right opportunity and this it is —— it's a mission from God."

For more information, see Englund's Web site, www.floatingairport.org.

Contact staff writer Mark Walker at (760) 740-3529 or mlwalker@nctimes.com.