SOUTHWEST HARBOR – If you see U.S. Coast Guard officers boarding some of those big luxury liners this summer, don’t be alarmed. They’re just being extra cautious after the Sept. 11 terrorist attacks that have shaken the nation’s sense of security on both land and sea.

“In the past as cruise ships have come in and out, we’ve kept an eye out on them. However, now it’s a very important part of our operations here,” said Lt. Brian Rush, operations officer for Coast Guard Group Southwest Harbor.

Rush said the Coast Guard, with limited staff and boats, cannot check all of the 64 ocean liners scheduled to dock in Bar Harbor this year, “but as much as we can, we will have a presence.”

Rush said officers will randomly select ships to board. They will not inspect them, but rather “make sure no one has taken over the bridge and that the crew is in full control of the ship.”

The Guard also will escort some of the cruise ships into harbor, he said, in conjunction with private escorts based in Belfast that are hired by the cruise liners.

The Coast Guard’s first mission is to provide search-and-rescue services along the coast. Therefore, when a boat leaves Southwest Harbor for Bar Harbor, the Guard is less able to respond to emergencies.

Rush said the Guard will call in backup help should an emergency occur while the regular-duty officers are away from their own port.

The Southwest Harbor unit is only equipped to have one boat staffed and ready at any one time, Rush said.

In addition to a heightened Coast Guard presence, Rush said the Immigration and Naturalization Service will be checking passenger lists from all ships from Canada and other foreign countries, while the marine safety division of the U.S. Coast Guard will continue checking ships of all sizes for safety problems and violations.