Another high-speed ferry for Marin riders could be ready by this spring as a deal progresses with a private boat operator on the East Coast.

Faced with several projects with its existing seven-boat fleet from summer 2017 through 2019, Golden Gate Ferry wants another boat to fill expected gaps. Golden Gate sends 42 ferries between Marin and San Francisco daily.

The sides have negotiated a deal for the boat over the last month and are ready to enter into a memorandum of understanding, a move approved Friday by the Golden Gate Bridge board.

“We have a tentative agreement,” said Jim Swindler, manager of the Golden Gate Ferry division.

The district would lease the boat for the first year for $225,000 so it can be used without having to meet California Air Resources Board requirements initially. When it is bought outright, it would be outfitted to meet state rules. The ferry will have to be shipped to Marin at a cost of $300,000.

The boat will cost the district $9.75 million to buy. When the 20-year-old vessel is upgraded, it will drive the cost to roughly $17 million, still $10 million to $12 million cheaper than the new boat. And a new one wouldn’t be ready for two to three years, officials noted.

The boat has a speed of up to 37 mph and, like the district’s existing high-speed vessels, has four engines and water jets, providing the redundancy that keeps it moving in case one system goes down.

The catamaran was designed by Incat of Australia. The boat, which is 121 feet long and 34 feet wide, was built on the East Coast and is similar in size to Golden Gate’s 400-passenger M.V. Del Norte.

This isn’t the first time Golden Gate has been interested in buying a used ferry.

In January 2009, it purchased two high-speed Washington state ferry system boats. The two mothballed ferries were bought for $2 million apiece, and the district ended up spending another $15 million refurbishing them. The capacity of each boat was increased from 350 passengers to 450. The boats were later named the M.V. Golden Gate and M.V. Napa and still ply the bay for Golden Gate.

The series of vessel projects that necessitate another ferry are scheduled for the next several years. The projects include new engines for the M.S. Marin and a major refurbishment of the M.S. Sonoma. The M.S. Marin and the M.S. Sonoma projects are to begin sometime this year.

In addition to those two projects, three of the district’s high-speed vessels are due for engine overhauls over the next 18 months. To accomplish that work, each ferry will likely be offline for up to four months.

“It’s good to have redundancy in our ferry system in case one goes down,” said Priya Clemens, bridge district spokeswoman. “When something happens with a ferry, we don’t want to disrupt service. We need to meet rider demand.”