The Miami Marlins may have scored big in the free-agent market, but they’re having a harder time getting past the U.S. Coast Guard.

After the Coast Guard denied the team’s initial request to keep the city’s 12th and 17th Avenue drawbridges down for an hour before and after home games, the Marlins are now asking for a 44-minute closure of the 12th Avenue Bridge before weeknight games.

Yet even that narrower request is not getting an immediate thumbs-up from the feds, who worry about too many regulations already halting traffic on the working river.

The Marlins would like to keep the bridge from going up and slowing traffic around their new East Little Havana ballpark while the stadium is filling up. They want the drawbridge to stay down from 6:46 p.m. to 7:30 p.m. before home games Monday through Friday.

That’s a much more modest proposal than the ballclub’s original wish to keep the two bridges down for one hour before the first pitch and one hour after the last out.

The original plan would have been “preposterous,” said Rick Eyerdam, executive director of the Miami River Marine Group, which represents cargo carriers and others who do business on the river. The bridges already stay down during rush hour until around 6 p.m., backing up evening boat traffic.

Sports fans have made their way to the stadium site for decades to watch football at the now-demolished Orange Bowl, which seated more than 70,000. The new ballpark seats much fewer people — 37,000 — but they will be going to the stadium more frequently. There are 81 home games a year, and, unlike weekend football games, most baseball games are on weeknights.

The Marlins — who made their initial request without consulting Eyerdam’s organizations or other river interest groups — reached out to locals for feedback after getting shot down by the Coast Guard. The Marine Group and the Marine Council of Greater Miami, made up mostly of recreational boaters, now support the ballclub’s scaled-back, 44-minute plan.

“After the first one, I think that they did some homework,” said Ed Swakon, president of the Marine Council. The Marlins came to him with a year’s worth of vessel traffic data, he said, to be matched with the team’s home schedule and figure out how many boaters might be affected by new bridge rules.

The Marlins tailored their request “after gaining a better understanding of the Miami River stakeholders, the Marine community and the function of the Miami River,” the team’s transportation consultant, Cathy Sweetapple, wrote the Coast Guard.

In response to her email, Michael Lieberum, operations chief for the bridge branch of the local Coast Guard district, wrote, “We have no plans on moving forward with any proposal for any type of change to the bridge schedule at this time.”

But the agency is still considering a 90-day trial to determine whether the Marlins’ request is workable. First, Lieberum wants river groups to weigh in on that idea. The Miami River Commission, an advisory committee, plans to take up the proposal in January.

“What we’re proposing to do is do a test to see whether or not this would even be workable,” Lieberum said. “From a boating standpoint, it’s rather difficult.”

Keeping the bridge locked down before Marlins games would force boats to rush through between the end of the 6 p.m. rush hour and the 6:46 p.m. baseball closure. On a typical weeknight, the bridge may be raised two to three times in the 44-minute period the Marlins are targeting for closure, Lieberum estimated.

On the other hand, if the bridge comes up too frequently as drivers try to get to the ballpark, car traffic could back up onto the 12th Avenue exit off the Dolphin Expressway.

Eyerdam, of the Marine Group, said the safety of pedestrians crossing the 12th Avenue Bridge on game days is also a concern. “What happens if there’s a bunch of traffic and pedestrians going to the game, and the police can’t clear the bridge?” he asked.

The Coast Guard’s Lieberum said any agreement would require stationing a police officer on either side of the bridge to ensure people are off it before raising the bridge for tows and large cargo vessels, which are protected under federal law and let through drawbridges at any time.

For now, the Coast Guard and assorted advisory groups sound optimistic about getting some sort of agreement in place with the Marlins.

“I’m convinced they don’t want to cause any potential problems on the river,” Eyerdam said.

Miami Herald staff writers Charles Rabin and Andres Viglucci contributed to this report.