PORTLAND – It’s big and green, and as soon as it robs a hitter of a home run, fans may mistake the towering left field wall at Hadlock Field for the “Green Monster.”

While the Boston Red Sox are adding 280 seats atop the Fenway Park icon, an homage to the baseball landmark will be unveiled to fans Thursday at the season opener for Boston’s new Double-A affiliate.

The ballpark’s makeover has deepened ties between the Portland Sea Dogs and a community 110 miles north of Boston where Red Sox loyalties run deep.

“It’s kind of like having our own little Fenway,” said Seth Begin, a Red Sox fan from Portland who recently got a job as a beer vendor at Hadlock. “It definitely gives the idea that the Red Sox organization is here now.”

From their 1994 inception until last September, the Sea Dogs were affiliated with the Florida Marlins. But the team jumped at the chance to become a Boston farm club, and now they’re playing the connection to the hilt.

The team replaced its teal and blue uniforms with red and blue versions, and the Red Sox patch is now prominent on Sea Dogs’ apparel.

For owner Dan Burke, the next step was a six-figure renovation of 6,975-seat Hadlock Field to evoke the ballpark he frequented as a high-schooler in Massachusetts.

Burke, a former president of ABC, recalled summer days at Fenway during the pennant-winning season of 1946.

Thanks to a broken elbow, he couldn’t go to work. “I think I paid $1.20 to sit in the bleachers,” he recalled wistfully.

Back then, Fenway’s tall left field fence abutting Lansdowne Street was plastered with advertisements. That changed the following year, in 1947, when the Red Sox decided to paint the monster green.

The Sea Dogs’ president and general manager, Charlie Eshbach, who grew up in Weymouth, Mass., remembers Ted Williams patrolling the grass in front of the Green Monster. Later, he was working in Boston’s front office when Carlton Fisk homered off the left-field foul pole in Game Six of the 1975 World Series.

Finished this week, the new wall in Portland matches the Green Monster’s 37-foot height and even features a Citgo sign and a giant Coca-Cola bottle, just like the wall at Fenway Park.

There are some differences, however.

Portland’s version is 160 feet long, compared with 240 feet at Fenway. The distance down the left field line is 315 feet, a shade deeper than the 310-foot line in Boston. Hadlock’s fence has a built-in electronic scoreboard, unlike the hand-operated scoreboard in Boston. And of course, Portland fans will not have the chance to sit atop their wall.

“We’re a likeness, not an exact replica,” Eshbach said.

The Sea Dogs did not have a name for their stadium’s new signature in time for Thursday’s opener against the Trenton Thunder, and they were turning to their fans for suggestions. The winner of a naming contest is scheduled to be announced during the second homestand of the season.

The ball will not bounce off Hadlock’s wood fence the same way it caroms from the hard plastic of Fenway. But by acclimating left fielders to a tall fence, the wall can still be a useful player development tool for Boston-bound prospects, Eshbach said.

Sea Dogs left fielder T. Brown expects there will be an adjustment period as players learn the wall’s angles. “It’s going to be practice, so once we get (to Fenway) we know what to expect,” he said.

Fan enthusiasm over the Sea Dogs’ new ties to the Red Sox are already paying dividends. Season ticket sales are up by 400 from last season, and individual game ticket sales are up by 70 percent, Eshbach said.

Devotion to the Red Sox is so strong in Maine because there are no other major-league teams nearby, said Will Anderson, a baseball historian from Bath.

“I think Maine probably has the highest percentage of Red Sox fans of any New England state,” he said.

Eshbach agrees that the fervor of Red Sox followers is particularly strong in Maine. “Maine was once part of Massachusetts, and I think they never lost their allegiance,” he said.