Against a bitter backdrop of union contract negotiations and charges of unfair labor practices, Oak Bluffs selectmen voted Tuesday to separate the functions of emergency medical service (EMS) personnel from call firefighters.

The action reverses the board’s decision of more than two years ago, when they voted to combine the two functions in order to improve response time and coverage on fire calls.

The decision to split the functions has the backing of the town personnel board and the fire/EMS command staff, including fire chief John Rose.

Mr. Rose said combining the two services has not worked out as planned.

“We thought making the full time staff, EMT/firefighters, or paramedic/firefighters, putting firefighters in their job description and allowing them to respond to calls during the day would help take some of the strain off the call (firefighters),” he said. “Unfortunately that has proven to not be the case.”

In recent years, the town has turned to EMS personnel from off-Island to fill full-time EMT and paramedic positions. Currently, nine of the 11 positions are filled by people who commute to the Vineyard from off-Island.

Mr. Rose said the medical personnel are often not available to answer fire calls, especially since the town handles most of the ambulance trips from the Martha’s Vineyard Hospital to Boston area hospitals. Mr. Rose said at night only one paramedic is on duty and must be dedicated only to medical calls.

“It was quite frankly an experiment that didn’t work,” Jack Collins, the town’s labor attorney and lead contract negotiator, told the selectmen Tuesday. “I don’t think anyone is here to point fingers at any particular reason. In the long run, putting it back the way it was would make a lot of sense.”

When the EMS personnel do respond to fires or monthly drills, they are often paid overtime, while working side by side with call firefighters who are paid a $2,500 annual stipend for all their service. That inequity has caused constant friction within the department, according to Chief Rose.

In July, EMS personnel organized a union under the International Association of Fire Fighters (IAFF). The town has recognized the union and is currently negotiating a new contract. Call firefighters are not members of the new union.

On Tuesday Bob McCarthy, who represents the local union in current negotiations, spared few words in blasting the proposal to split the department.

“I believe any action tonight to separate the department would be regressive,” he said. “I can guarantee you if this union didn’t come in here eight or nine weeks ago, we wouldn’t be here tonight. This whole charade is union retaliation.”

In a prepared statement read to selectmen, Mr. McCarthy directed much of his criticism at Chief Rose, saying the town will eventually have to raise money to settle formal charges filed with the Massachusetts Department of Labor Relations.

“He slashed overtime, threatened members, eliminated longstanding benefits, and started surveillance,” said Mr. McCarthy. “He prevented paramedics from responding to fires.

The union has filed five unfair labor practices against the town with the commonwealth, “based primarily on the chief’s behavior,” Mr. McCarthy said.

Selectmen Brian Packish and Mike Santoro took exception to Mr. McCarthy’s remarks.

“For you to say the foundation of this department is crumbling, or will crumble without the union, you obviously don’t know the men and women,” said Mr. Santoro. “Union or nonunion, these are great people and they’ll continue to do their jobs.”

The town sought recommendations from retired Brewster fire chief Roy Jones, who serves as a consultant to the selectmen. Among his recommendations were to use the current organizational structure for the present, but to eventually create a new position to manage the separated EMS department. That manager would report to Chief Rose under the recommendations.

“Oak Bluffs is definitely in a unique position in providing ambulance service and I understand some of the issues that have arisen,” Mr. Jones wrote in his recommendations. “Based on the information I have been provided and working with Chief Rose I must agree that fire and EMS in Oak Bluffs be operated as two independent branches with the fire chief as the leader.”

Selectmen Greg Coogan said the decision was difficult.

“But this is why we sit here, because that’s our job, is to make difficult decisions,” said Mr. Coogan. “Some people are not going to be happy with my decision and some people will agree. I personally will make a decision that I think will make this a stronger department, not a weaker department. I do think we have a problem, and I do think we have blurred lines. Our job now is to unblur those lines and make it a more efficient department.”

Following the discussion, selectmen voted unanimously to remove all firefighting duties from the job description of EMTs and paramedics.