When it collided with a Block Island ferry in thick fog Wednesday, the Coast Guard vessel Morro Bay was returning to New London from a change of command ceremony in Newport.

Lt. Douglas Wyatt was installed as the new commander in a ceremony Tuesday, the Coast Guard said in a Wednesday night statement.

Wyatt, who enlisted in the Coast Guard in 1978, had previously been the officer in charge of the 65-foot ice-breaking tug Coast Guard cutter Hawser.

He had also served as the executive petty officer at Station Castle Hill in Newport, and in the same role on the 65-foot ice-breaking tug Coast Guard cutter Wire. He was also the commanding officer of Coast Guard Station Fire Island, N.Y.

The 140-foot Morro Bay, based in New London, is an ice-breaking tug. It was incorrectly described at first by the Coast Guard as a buoy tender.

A cause for the collision, which dented the bow of the ferry Block Island and left a gash on the rear starboard railing of the Morro Bay, has not yet been determined, the Coast Guard said. Interviews and drug and alcohol tests are being conducted on members of both crews.

No one was seriously injured, although 3 of the 257 passengers on board the Block Island were checked out at an island medical center.

The ferry, sidelined but not disabled, navigated under its own power to a boatyard in Providence later Wednesday, said William A. McCombe, spokesman and director of security for the ferry service.

“The Coast Guard has to do a full inspection before it can be put back in service,” McCombe said yesterday. “We’re hoping we’ll have it back in service in a very short time.”

Another ferry, the Manitou, was reassigned to take the dented ferry’s place in the posted schedule.

Although it’s a holiday weekend, the ferry service will follow its regular Friday schedule of 10 departures from Point Judith and 10 returns from the island today, and the normal Saturday and Sunday runs will continue, McCombe said. The ferry service has a special schedule for some holidays, but not for the Fourth of July weekend, he said.

Two changes have resulted from the collision. One is that the once-daily round trip from Newport has been canceled to free the Manitou for Point Judith-Block Island service.

While the once-daily Newport service isn’t running, McCombe said, people wanting to board in Newport are being advised to drive to Point Judith (about a half hour, he said) and catch the ferry there. The street address in the village of Galilee is 304 Great Island Rd., Narragansett, R.I. 02882. Passengers who drive from Newport, he said, would get preferential seating if passengers have to be turned away from full boats.

Also, Interstate Navigation added one boat yesterday morning to deliver vehicles whose reservations had to be canceled after the collision. The reservations desk moved quickly to notify those drivers and reschedule their trips, McCombe said.

The ferry service requires reservations for vehicles and recommends they be made well in advance, at least four months ahead for holiday weekends. Schedules are posted and reservations can be booked on its Web site, www.blockislandferry.com.

The Block Island, along with the Anna C and the Carol Jean, are the larger boats in the Interstate Navigation fleet. They carry about 40 cars and as many as 1,000 people. The Manitou is among the smaller boats, carrying about 15 cars and up to 400 people. When it serves the Newport route, it doesn’t take vehicles.

Wednesday’s crash occurred exactly 25 years after another collision involving a Block Island ferry. In that July 2, 1983, crash, Michael P. Smith, captain of the Block Island ferry, was charged by the Coast Guard with misconduct and negligence.

The ferry Yankee — owned by Interstate Navigation of New London — was headed for Providence from Block Island with 140 aboard. The vessel collided with a 464-foot Liberian-registered freighter in heavy fog about six miles southeast of the Brenton Light Tower, injuring at least three people.

— With reports from projo.com

dnaylor@projo.com