The Steamship Authority approved plans last week to convert a third former offshore oil vessel into a freight ferry. 

The ferry line board of governors Thursday approved a $17 million retrofit of the Louisiana vessel. The ferry, which will be called the M/V Monomoy, will eventually join two other newly converted freight vessels that are set to join the Steamship fleet later this year. 

The conversion cost is slightly higher than the price tag for the other two freight ferries, which Steamship Authority staff chalked up to supply chain issues, rising shipyard costs and other factors. 

The other freight vessels cost about $13 million each to convert, though they ran into several issues, ballooning the costs and pushing back the delivery dates. Those setbacks will be taken into account during the new conversion process, staff said. 

“Based on the shipbuilding producer price index over the last 15 months, they have seen an increase of 18 per cent in the costs in the shipbuilding industry,” said Steamship general manager Robert Davis. “It’s still impacted by supply chain, labor shortages, power, insurance and overhead charges.” 

The M/V Monomoy will be lengthened, widened and will receive an overhaul on its engines, as well as bow and stern thrusters. The main propulsion engines, which have logged a longer time at sea than the first two conversions, will also meet a higher environmental standard, resulting in lower emissions and fuel usage.

Mark Higgins, the Steamship Authority chief operating officer, estimated that the engine overhaul could cut fuel consumption by 5 to 9 per cent. 

Though this was greeted with enthusiasm by board chair Bob Jones, others questioned why hybrid technology wasn’t looked into. 

“What are the financial impacts of looking at this enhanced conversion versus making this vessel into a hybrid,” Vineyard governor James Malkin asked. 

Mr. Higgins said that a hybrid ferry would have cost around $21 million, but the upgrade could be looked at when these vessels go in for their mid-life upgrades. 

“Right now, I think this is the best option to move this project forward,” Mr. Higgins said.

The Monomoy’s conversion will be done by Alabama Shipyard — the company that also converted the Aquinnah and Barnstable. The work is expected to take about 10 months from when the retrofitting begins.