Thousands of ferry cancellations between Woods Hole and Martha’s Vineyard over the past two years, followed this month by the abrupt departure of the Steamship Authority’s longtime engineering and maintenance director, have had Islanders questioning the reliability of their lifeline across Vineyard Sound.

“There is a perception that cancellations are up,” said SSA communications director Sean Driscoll. “It can vary widely from year to year.”

Despite the perception, according to numbers provided by the boat line, cancellations in 2019 were down significantly over the previous two years.

From January through November, the latest month for which the numbers were made available, the Steamship Authority called off 830 scheduled trips between the Cape and Islands from January through November.

That total pales in comparison to 2018, when 1,463 trips were canceled, more than 1,000 of them on Vineyard routes. Many of those cancellations were due to mechanical problems aboard the vessels Martha’s Vineyard, Woods Hole and Island Home, which among them had racked up more than 550 cancellations by the end of April.

Mechanical issues caused 617 of that year’s cancellations, weather 625 and 221 were attributed to “other,” a category Mr. Driscoll said is used for cancellations when specific trips are under-booked. “If there’s a trip that has low bookings and we can accommodate passengers on another trip, we do that occasionally,” he said.

In 2017, the boat line had 372 mechanical cancellations, 574 for weather and 472 for other, totaling 1,418.

In the first 11 months of 2019, weather accounted for 540 missed trips. Another 234 trips were canceled for mechanical reasons and 56 for other.

Not all cancellations translated into missed crossings for ferry passengers, Mr. Driscoll said.

When ferries break down, he said the boat line substitutes other SSA vessels when they are available. But problems arise when the backup ferry also malfunctions, as happened last month after the freight boat Katama went out of service due to steering problems.

The SSA plugged Katama’s sister ship Gay Head into the scheduling gaps, and then the Gay Head also suffered a mechanical problem, leading to more missed trips.

While Gay Head was able to return to service in less than a day, the Katama has remained at the boat line’s maintenance facility in Fairhaven undergoing repairs. Mr. Driscoll said the ferry was expected to be back in service Friday.

Across all its routes and ferries, the boat line completed 22,208 crossings in the first 11 months of last year, out of 22,414 originally scheduled.

The Vineyard routes saw more trips completed than originally listed, with ferries making 15,461 crossings when 15,408 were initially planned.

And while the boat line can add trips to replace disabled vessels and match customer demand, it is powerless over the weather.

Of 350 cancellations over 11 months on the two routes to Martha’s Vineyard, 188 were for weather, 24 mechanical and 32 other.

October was the cruelest month for ferry passengers, who saw the longest suspension of service since the blizzard of February 2013 shut the SSA down for nearly 40 hours.

“We were down for two days Columbus Day weekend,” Mr. Driscoll said. “It was a serious storm. Nothing was running.”

Overall, in October 284 trips were canceled, 174 of them on Vineyard routes. November, by comparison, saw 73 weather-related cancellations on all SSA routes.

The SSA’s smoothest sailing was in July, when there were no weather cancellations and four each for mechanical and other reasons, and May, when four trips were canceled for mechanical reasons. Nantucket had the roughest 2019, with 254 cancellations due to weather and 204 for mechanical reasons. The high-speed ferry Iyanough lost one of its four engines in April, accounting for more than 70 missed trips that month.

Keeping the current fleet of 10 ferries in operating condition was the responsibility of the boat line’s director of maintenance and engineering, Carl Walker, until this month.

A 24-year Steamship Authority veteran, Mr. Walker’s employment ended Jan. 3, Mr. Driscoll confirmed in a terse email the following day.

Pressed for more information, in a followup email on Jan. 6 he said Mr. Walker’s position had been eliminated due to organizational restructuring at the boat line.

“Oversight of the department now falls to director of marine operations Mark Amundsen,” Mr. Driscoll wrote.

The realignment was not one of the recommendations from the comprehensive review conducted in 2018 by HMS and Glosten.

The maritime consultants recommended a management chart placing the now-eliminated maintenance and engineering position on the same tier as the directors of marine operations and shoreside operations.

HMS recommended that all three positions report to a chief operating officer, a new position directly under general manager Robert Davis.

Mr. Davis has resisted the idea of having the directors report to anyone other than him. Several new positions were created at the consultants’ urging, including dividing the former director of operations position into separate marine and shoreside posts now held by Mr. Amundsen and Alison Fletcher. But the recommendation for a chief operating officer has received little attention from the SSA board of governors.

Mr. Davis and Mr. Amundsen were unavailable for comment this week.

As for cancellations, the overall message, Mr. Driscoll said, is that they are always a possibility.

“People . . . think that the Islander is the only good boat we ever ran,” he said, referring to the long-serving ferry, built in 1950, that plied the Vineyard route until she was retired in 2007 and replaced by the Island Home.

“They tend to forget that the Islander did cancel and there was often three feet of water on the freight deck,” Mr. Driscoll said.

“The Islander was not going to run on Columbus Day weekend.”