ROCKLAND – Based on its timing, Saturday’s Rockland HarborFest might seem like a party thrown for locals, celebrating their surviving another hectic summer.

After all, Rockland has become festival central in recent years, drawing tens of thousands to events such as the North Atlantic Blues Festival, the Wooden Boat Show, the Maine Boats and Harbors Show, and the Lobster Festival during July and August.

But the first-ever HarborFest is really an attempt to attract visitors – many from Maine – to the area during the less-busy months, explained Bob Hastings, executive director of the Rockland-Thomaston Area Chamber of Commerce.

The free festival, in Harbor Park off South Main Street, will offer a jampacked day of music. Country-rock legend Poco is the headliner, but the Chamber also was able to land the ’60s group It’s A Beautiful Day.

Rounding out the bill are Maine performers Sarah Cox and Nate Schrock; Diesel Doug and The Long Haul Truckers; and Blue Northern.

“One of our charges is to build ‘shoulder-season’ business,” Hastings said.

Since about 60 percent of tourism spending in the state is created by Maine people visiting other parts of Maine, he hopes a free day of music on the city’s revitalized waterfront will lure people to town.

The music was lined up by local promoter Chuck Kruger of Thomaston, Hastings said.

The park opens at 11 a.m. In addition to the music, there will be arts and crafts booths and food and drink concessions. The Isaac B. Evans schooner will hold an open house, allowing visitors to wander its decks.

Sarah Cox and Nate Schrock, members of the Portland-based band The Coming Grass, kick things off at 12:30 p.m. Kruger said Cox has a new CD out.

“She’s a wonderful young singer,” he said.

The music will be like an unplugged version of The Coming Grass, Kruger said, “sort of acoustic bluegrass with a rock ‘n’ roll sensibility.”

Diesel Doug and The Long Haul Truckers are a staple of southern Maine, he said, playing “kick-ass country rock.” Their set is scheduled to begin at 2 p.m.

Blue Northern is a midcoast band, Kruger said, playing acoustic bluegrass-roots music. Members include Peter Davis and David Lewis. They perform at 3 p.m.

It’s A Beautiful Day is best known for its hit “White Bird,” a jazzy tune with long instrumental passages that was a staple of FM radio in the late ’60s and early ’70s.

Original members David LaFlamme, whose electric five-string violin characterized the band’s sound, and his wife, Linda LaFlamme, who plays keyboards, appear in the current configuration. It’s A Beautiful Day performs at 4 p.m.

Poco is a seminal country-rock band whose career paralleled that of the Eagles, but never achieved the same success. The band’s personnel read like a who’s who of Southern California rock: Jim Messina (later of Loggins and Messina), Richie Furay (earlier a member of Buffalo Springfield), Randy Meisner (later of the Eagles), and Timothy B. Schmit (later of the Eagles).

Original members Rusty Young and George Grantham will be on hand Saturday, along with Paul Cotton, who played on most of the band’s hits. Rounding out the line-up is Jack Sundrud, who has been playing with the group for about 10 years.

The band’s hits through the 1970s and early 1980s included “Pickin’ Up the Pieces,” “A Good Feelin’ To Know,” “Crazy Eyes,” “Indian Summer,” “Crazy Love,” “Heart of the Night” and “Rose of Cimmarron.”

Poco’s set will begin at 5:15 p.m.

No coolers or pets will be allowed in the park. For more information, see www.therealmaine.com or call 596-0376.