Three of the Steamship Authority’s four freight ferries — the Gay Head, Katama and Sankaty — will need to be replaced within the next three to five years, a marine survey has found.

The survey of the SSA fleet was done by Marine Safety Consultants of Fairhaven, whose report was aired at the monthly meeting of the boat line governors Tuesday.

The Gay Head, now 41 years old, is functionally obsolete and needs “rigorous preservation and expense” to keep operating, according to the report, while the Katama (aged 40) and Sankaty (41) are “at or near [the] extent of useful life.”

Surprisingly, the oldest freight boat of all has the most time left — five to seven years, according to the report.

“The Governor, though it’s 68 years young right now, actually has a longer useful life expectancy than the other three freight boats,” SSA general manager Robert Davis told the governors, noting that the vessel was repowered in 2011 and has had new generators in recent years.

Mr. Davis said the boat line is looking to replace its aged-out freight ferries with converted offshore supply vessels, many of which have been idled since the latest downturn in undersea oil exploration.

“These assets are sitting there, [and] the indications are that there are some opportunities,” he said.

A similar strategy brought the Gay Head and Katama into the SSA fleet in the 1980s, Mr. Davis said. Like the Sankaty, purchased in 1994, the two sister ships are former oil platform supply vessels refitted as freight ferries.

“There was a downturn in the market [and] we were able to acquire them for cents on the dollar,” Mr. Davis said.

The obsolescence survey found that the SSA car and passenger fleet is also aging out, with the exception of the six-year-old Woods Hole and the 15-year-old Island Home.

The 48-year-old Nantucket has five to seven years of useful life remaining, according to the report.

The survey also pegged the Eagle, built for the SSA in 1987 to ply the Nantucket route, for replacement in 12-14 years, as long as it is refitted and repowered by 2025.

The Martha’s Vineyard, built in 1993 and refurbished in 2018 with a subsequent dry dock last year, will need replacement in 18 to 20 years.

This is the third fleet survey the SSA has commissioned over the past decade, Mr. Davis said.

In 2012, he said the emphasis was on vessel construction. A 2018 survey focused on preservation methods, and the latest study, conducted in 2021, was to determine whether the SSA’s preservation efforts have been effective.

The answer to the last question appears to be both yes and no, according to the survey results. While rigorous maintenance and overhauls have kept older ferries operating, Mr. Davis said, the returns begin to diminish when a vessel reaches an average lifespan of 25 to 30 years.

“As a point of reference, the average age of [the SSA fleet] is 34 years old,” he said. “There comes a time when the cost of repairs and replacement parts becomes higher than the cost of a new [vessel] . . . Equipment becomes obsolete, [and] parts no longer available for repair.”

But financing a new ferry poses challenges. To produce another boat like the diesel-powered Woods Hole would cost close to $45 million in today’s money and take 15 to 18 months to build, Mr. Davis said.

“It’s a balancing act in therms of finances, in terms of what can be done, but also taking into account the need for service,” he said.

The cost of an electric or hybrid ferry is presently unknown, but Mr. Davis said a report on alternative propulsion systems by Elliott Bay Design Group, the Seattle-area naval architecture and engineering firm that designed the Woods Hole, is due to be ready by next month.

On Tuesday, Mr. Davis told the SSA board that masks are still required aboard all ferries, which remain under a Coast Guard order.

On Wednesday, the requirement was dropped after the Coast Guard lifted its rule.

In his report to the board, Mr. Davis said shoreside work on the Woods Hole terminal is completed, with the third slip fully functional from a marine standpoint, although supply chain delays have slowed the installation of its ticket reader.

The next phase of the terminal project will begin in September with site work for the permanent ticket office and its utility building.

Winning construction bids are expected to be chosen in the fall with the building process to begin at the start of 2023, Mr. Davis said.

On the Vineyard side of the sound, the Oak Bluffs terminal is 80 per cent of the way through a pile-wrapping project designed to give the pier’s 400 pilings another 20 to 25 years of service, director of marine operations Mark Amundsen said.

The $1.4 million dollar project, which includes the installation of six new pier pilings, is slated for completion April 29, well in advance of the terminal’s season opening in May.

In other business, Mr. Davis said a request for proposals from firms interested in providing freight service between the Vineyard and New Bedford, issued March 21, has already attracted 20 responses from as far away as Turkey.

The deadline for bid submissions is August 2, Mr. Davis said, with evaluations to be completed by the end of September and finalists identified by the end of October.

Governors popstponed action on a request to license a barge freight service between New Bedford and Nantucket, to allow time for staff to draft a contract that addresses the concerns of state Rep. William Strauss, whose 10th district includes New Bedford.

In a letter to the SSA, Mr. Davis said, Mr. Strauss supported the service proposed by New Bedford-based 41 North Offshore, but wants a stipulation that it cannot be used to ship waste to New Bedford.

The barging company’s anchor client for the service would be the United Parcel Service, Mr. Davis said.

A special meeting will be called once the contract is drafted.

Governors also postponed action on a request from the boat line’s longtime food and drink concessionnaire, Centerplate, to waive its contractual minimum payment for a third year.

“I think their request is a reasonable one,” SSA attorney Terence Kenneally said, noting that the company has struggled with staffing and supply shortages since the SSA permitted concessions to resume last year.

“We didn’t let them back on the vessels until May,” Mr. Kenneally said.

The SSA’s take from concessions for the year was $346,000, Mr. Kenneally said, compared to $843,000 in 2019, the last pre-pandemic year.

“Hopefully things are going to be improving here and the traveling public is going to be coming back out and enjoying the concessions on the boat,” he said.

But Falmouth governor Peter Jeffrey balked slightly at waiving the minimum. “I don’t know why their hiring problems or supply chain problems should become the authority’s burden to bear,” he said. “Why aren’t we countering?”

Traffic aboard the ferries is rebounding solidly from pandemic depths, Mr. Davis said, pointing to February numbers showing a 19.1 per cent increase over the same month in 2021 in the number of passengers on the Vineyard route.

Vehicle traffic was up 7.4 per cent per cent over last February and freight increased by .8 per cent on the Vineyard route, Mr. Davis said.