When a Northeast Harbor lobster boat recently caught fire and sank 20 miles out in the Atlantic, 15 to 20 other lobstermen dropped everything and raced to rescue David Graves and his son Ryan, adrift on their life raft in a thick fog. It was neither the first nor the last time that they would help a fellow fisherman in trouble.

Ryan had been able to reach a friend and lobsterman, Chris Candage of Bar Harbor by cell phone with a call for help and their position south of Mount Desert Rock. Mr. Candage alerted others, and within minutes he and at least 10 boats from Islesford and others from Bar Harbor and Winter Harbor were speeding to the scene. Several Coast Guard vessels and a helicopter and jet from Cape Cod joined in the search.

The boats crisscrossed the area through fog so thick the seamen could hardly see the bows of their own boats. As it turned out, a Coast Guard vessel passed within feet of the life raft, Ryan called out on his cell phone. Homing in on the phone signal and the sound of a whistle, the boat closed on the raft and picked up the two men, shivering from several hours of exposure even though they had put on their immersion suits.

Rivalry and competition are commonplace among the various lobster fleets, but no one hesitated to hurry to the aid of a distressed crew. Fortunately, the Graveses had kept their survival suits handy and had been able to launch their life raft before their boat sank. The Coast Guard said they had been able to board the raft without getting wet.

The cause of the fire has not been officially determined, but Mr. Candage supposes that inflammable power steering fluid may have sprayed onto the hot engine. The 44-foot boat Midnight, built in Lamoine two years ago, was valued at more than $500,000 and presumably was insured. The Coast Guard is investigating details of the rescue and whether any pollution resulted from the sinking.

Mr. Graves could not be reached for this commentary, but he may have been benefiting from the customary practice of lending a boat to someone who has lost a vessel so that he can continue fishing.

The search cost the searchers at least $45 apiece in diesel fuel and the loss of a day’s fishing, but they all knew that others would be helping them in any emergency.

It was one more instance of the working of an unwritten law of the sea: Help out whenever the need arises.