SOUTHWEST HARBOR – “Mayday. Mayday. Mayday.”

At any time, that distress call can break though the monotonous Channel 16 static that permeates the communications center at the U.S. Coast Guard station in Southwest Harbor. The call on the international distress hailing frequency will immediately set in motion the plan that will guide a search and rescue operation.

“I’ve been at this for 22 years and I still get butterflies in the stomach,” said Kenneth Stuart, a Coast Guard veteran and now a civilian Search and Rescue, or SAR, controller at the Southwest Harbor station.

“You try to make the right decisions and you treat it as if it was one of your family out there,” Stuart said. “You can’t be complacent. You have to treat any and every situation like it is the first time.”

The reaction and the response is the same whether the call is a real emergency or whether it is a hoax. And, too often, the Coast Guard SAR teams are called into action to respond to prank calls that expend time and money, and places them in potential danger. In addition, it can impede their response to a real distress call, according to Ensign Ben Crowell, the Coast Guard’s public affairs officer at Southwest Harbor.

Crowell notes the 1990 case off the coast of Cape Cod in which the Fishing Vessel SOL E MAR broadcast a distress call.

“It was a four-second burst,” he said. “Within a few seconds, a second vessel came up on Channel 16 and made a similar broadcast, only mocking the Coast Guard and the other vessel.”

The officers standing watch assumed that both calls were from the same vessel and that it was a hoax. No action was taken until the vessel was reported overdue five days later. The man and his son on the SOL E MAR were never seen again.

That incident spurred changes: improved equipment, procedures and training. It also led to new laws that make it a federal crime to call in a false broadcast, punishable by a fine of up to $5,000. If convicted, a person also could be liable for the cost associated with a search effort.

Still, the problem of hoax calls continues. In the past three years, the Coast Guard has responded to 1,202 probable and confirmed hoax calls around the country at a cost of $3,129,521 to the federal government. In 2005, the SAR team at Southwest Harbor received three hoax calls, and 15 uncorrelated distress (probably hoax) calls. In a recent five-day span, the station received two obvious hoax calls.

Often, Stuart said, alcohol is involved. Or, as on one occasion recently, the call can be a child playing with the radio on his father’s boat while it sat in the driveway.

Each call sparked the same response in the communications center, where two-member teams keep watch 24/7. The watch stander is the ears of the operation monitoring Channel 16 and other emergency calls.

“You listen to static for 12 hours and then all of a sudden you get the call,” said Jason Gridley-Waters, a reservist serving his weekend duty recently.

Sometimes the call is not all that clear and there is initial uncertainty.

“You have to listen closely,” he said. “My main job is to gather information and find out as much of the situation as I can and pass it on to the SAR controller.”

Even if they suspect a hoax call, the planning for a SAR mission begins while the call is evaluated. All calls are digitally recorded, and staff members will replay over and over, washing it through filters, to determine if it is real.

“Even if we determine it is a hoax, it still has to go to Boston to the First District commander,” Stuart said. “He makes the final decision.”

As controller, Stuart said, his job is to plan and coordinate the search and rescue mission. The first response is to broadcast Urgent Marine Information Broadcasts to alert other boats that might be in a position to respond to the scene or provide additional information to the Coast Guard. They also alert the SAR teams who will begin to ready themselves for a mission. Those broadcasts go out over the same Channel 16 frequency, according to Crowell.

“The radio only works one way,” he said. “As we are sending out these radio broadcasts, no one else can transmit on Channel 16. So, if there were someone really in distress, we could not hear them.”

Using computers and the many charts in the communications center, Stuart will develop a search grid for the various “assets” that would be used in a search and rescue effort. Each grid represents the area that could reasonably be covered in two hours on the water or one hour in the air.

The cost of operating the boats and aircraft is enormous, but it is justified for a legitimate search. Worse, Crowell said, it degrades the service to the rest of the public.

The boating public needs to understand that marine radios are for maritime communications and emergencies, he said.

“When we get these calls, it severely drains our limited resources and has already resulted in the loss of life at sea, a tragedy that could clearly be prevented by a more informed boating public,” he said.