The Steamship Authority governors Tuesday voted to go forward with designs for a new freight ferry with a capacity for 384 people.

For almost a year, the SSA has been looking at plans for fleet replacement, beginning with replacing the freight ferry Governor. In August, the board opted in favor of a 235-foot freight vessel similar in size to the ferry Martha’s Vineyard, but asked for price comparisons between a boat with a 384-person capacity and a 512-person capacity.

Meeting in Woods Hole Tuesday, the governors agreed with a management recommendation to opt for the smaller of two potential ferry designs.

The Elliott Bay Design Group, which is designing the new vessel for the Steamship Authority, said the higher capacity ferry would cost about $2 million more than a smaller vessel, and would cost an additional $200,000 a year to operate.

“With the difference in price it’s just not worth it,” Barnstable governor and board chairman Robert O’Brien said.

The recommended ferry would have a maximum capacity of 384 people, passengers and crew combined.

SSA general manager Wayne Lamson said 92 per cent of 2013 large vessel trips on the Vineyard route carried fewer than 400 passengers, and boat line management felt that the 384-person ferry would be adequate. He also noted that the ferry could be modified in the future if it proved insufficient.

Right now, the freight ferry Sankaty has the highest passenger capacity of any current freight boat, with the ability to carry 290 passengers.

Mr. Lamson later told the Gazette that the new freight vessel will be used as a supplement to other vessels, doing mostly freight trips during the week, freeing up space on the other vessels. Mr. Lamson said there will be a “domino effect by having a slightly larger truck-carrying capacity.”

He said the new ferry will have the flexibility to run any time of year on either route, though it will run primarily on the Vineyard route. “It’ll be nice just to have the extra vessel, to be able to swap in and give other vessels more time in repair,” Mr. Lamson said. He said the new vessel will be able to make more trips in the spring and the fall.

Mr. Lamson said a preliminary design for the ferry will be completed by the end of March, and full design specifications are expected by October. A construction contract is expected to be awarded by January 2015, and the new ferry should be making trips by May 2016.

The final cost of the ferry hasn’t been nailed down, but Mr. Lamson said the preliminary estimate is $35 million. The ferry will be a drive-through boat, he said, so cars won’t have turn around, and will likely be open in the middle to allow for more vehicles, with four truck lanes and five car lanes.

The cost and the design will be refined through the process, Mr. Lamson said.

Once the new ferry is in operation, Mr. Lamson said, the freight ferry Governor will be scrapped or sold.

In other business, treasurer Robert B. Davis said January passenger traffic was down just over three per cent compared to January 2013, and car traffic was down 1.8 per cent. Truck traffic was down about 0.3 per cent.

Mr. Lamson said passenger traffic was up in December, with the number of passengers up nine per cent, car trips up 6.6 per cent, and truck trips up 6.3 per cent. He said the increase could be attributed to better weather and fewer trip cancellations compared to the weather in December 2012.

Overall ferry traffic was up slightly in 2013, with passenger trips up 1.6 per cent over the last year, car trips up about .5 per cent, and truck trips up 5.5 per cent. Vessels made 22,050 trips, and the net operating income for the year was $304,705 lower than budget projections.