John Daley, an Oceanside native, business owner and regular beach visitor, said he was surprised to see the change in dredging technique.

"I've lived here my whole life and I've never seen a setup like that before," Daley said.

The Megan-Renee, whose home port is Portland, Ore., has worked since April 2 to deepen the basin for more than 1,000 private pleasure boats, commercial fishing boats and much larger ships used by Camp Pendleton and the U.S. Coast Guard.

On a recent cloudless morning, Capt. Del Thompson guided the massive dredge through a series of maneuvers, dancing, with the aid of a tug boat, close to the rock jetty that protects Oceanside Harbor from the pounding surf.

"That's it, we're right where we want to be," Thompson said into his radio, notifying the rest of the crew that he was about to put each of the Megan-Renee's three 70-ton feet on the bottom.

Ocean currents cause Oceanside's harbor to fill with sand, and the Army Corps of Engineers has conducted an annual dredging operation since it opened in the 1960s.

Dredging efforts began in the Oceanside Harbor on April 2 and are expected to finish soon. The Corps of Engineers hired contractor J.E. McAmis Inc. to dredge 160,000 cubic yards of sand from Oceanside Harbor at a cost of $1.7 million.

A solid stance

Thompson said that successful dredging requires firm footing. For the Megan-Renee, that footing comes from three 70-foot-tall metal columns called "spuds." Each metal pile is connected to its own hydraulic motor, allowing engineers to raise and lower them at will.

"There they go," Thompson said, watching the spuds sink to the bottom and steady the barge's gently pitching deck.

With her three feet planted firmly, Megan-Renee could get to work. Sitting in a comfortable chair in a noise-shielded cabin several stories above the water, Thompson guided the barge's giant yellow excavator arm through a series of dips and pivots, scooping tons of sand from the bottom and dumping it on a steel scow moored to the barge's starboard side.

"This is the largest excavator on the West Coast," Thompson said. "It's got 230,000 pounds of breaking force."

The barge's 27-year-old captain is not a man who likes making grand statements. When asked what it's like to wield such power, he noted that computer controls make the experience somewhat ... automatic.

"It's like playing a big video game," Thompson said.

Operator Steve "Barney" Barnes, a gravel-voiced veteran with experience excavating contaminated "superfund" sites, broke into a grin when asked to describe the power shovel's power. Though his work keeps him on the water, the operator said he has always daydreamed about seeing what the powerful appendage could do in a new car lot.

"It would be whap whap whap. I really like it," Barnes said, a wide grin flashing under his white hard hat.

Dump don't pump

The Army Corps performs annual maintenance dredging in the harbor to keep it at least 20 feet deep. In previous years, contracting companies have used a different type of barge -- equipped with a large underwater vacuum -- to suck sand from the bottom. Then a pump on the barge sent the sand and water mixture through a long pipe on shore, spewing the material directly onto the beach.

But McAmis uses a different technique, depositing scoop after scoop of sand into a large floating metal scow. A tugboat then tows the scow out to sea, dragging it to a dump site just off the Oceanside beach between Wisconsin Avenue and Oceanside Boulevard. When positioning equipment shows that the scow is in the right location, the scow's bottom splits open, dropping the sand on the sea floor below.

The Corps and city officials said they expect to see a large portion of the sand eventually wash up on shore.

Bob Guza, an oceanographer with Scripps Institution of Oceanography who studies how ocean currents move sand along the beach, said there is no hard-and-fast way to predict what will happen to the sand once it is dumped.

"All sites are different to some degree," Guza said. "At other sites where they have done an offshore placement, sometimes it has come onto the beach and sometimes it hasn't."

Guza said there is only one way to be sure that dredged sand ends up making wider beaches: "Clearly, there is nothing as reliable as putting the sand directly on the beach."

The 160,000 cubic yards of sand to be dredged by Megan-Renee is insignificant in terms of recent history. In 2001, the San Diego Association of Governments dumped 2 million cubic yards of sand on 12 local beaches at a cost of $17.5 million.

Science suggests that littoral currents, which run parallel to the beach, carry sand away from beaches in the winter months and bring it back in the spring. Those currents are interrupted by the harbor's rock jetty. The jetty snags some sand and causes it to build up in the harbor basin. Sometimes the sandbar in the entrance gets so shallow that waves break inside the harbor, creating a hazard for boaters.

"I think it's clear that sand moves along shore and, if you build a harbor, you're going to interrupt that flow," Guza said.

He added that science has not yet come up with a way to keep sand from building up in harbors like Oceanside's.

"There is no way, when they built Oceanside Harbor, that they could have understood what the littoral drift was at that location," Guza said. "At the time that was built in the 1950s, we had very poor understanding of littoral drift."

Most of the crew that operates and maintains the Megan Renee lives in and around Portland. The crew just finished deepening the Marina Del Ray Harbor and worked on a much more difficult project at St. Paul Island in Alaska. There, the excavator chipped rock from the sea floor near active oil pipelines. The barge's next project will take place in the Columbia River in Oregon.

-- Contact staff writer Paul Sisson at (760) 901-4087 or psisson@nctimes.com