FAJARDO, P.R. — Puerto Rico, dealt only a glancing blow by Hurricane Irma, has become an impromptu emergency hub for its Caribbean neighbors that were left devastated by the storm’s wrath.

Puerto Ricans relieved at being spared the worst destruction donated water, clothing, first aid and other supplies, and dozens of recreational boaters sailed to nearby islands to deliver the assistance and evacuate now-homeless islanders on the return trip.

A 54-foot dive boat named the Tobias cast off on Sunday morning from the marina here, the largest in the Caribbean, and made its way eastward under a searing sun to St. Thomas in the Virgin Islands, the fourth vessel of the day to make the trip. It would return later crowded to capacity with 46 St. Thomas residents escaping the near-total devastation of the island.

“We were very blessed here, and we have to do everything we can to help,” said Cristina Morales, the owner of the Tobias.

Government-led missions have also been evacuating people from the islands to Puerto Rico. Some 1,200 mostly American citizens, have been carried from Saint Martin and Saint Thomas in six C130 aircraft, and more than 50 patients have been airlifted to Puerto Rican hospitals, officials said.