Interstate Navigation, which runs the year-round traditional ferry to the island from the Port of Galilee, wants to replace its 250-passenger seasonal high-speed boat with a new $10.5-million vessel that can carry twice as many passengers.

After years of fighting a rival's bid to bring new high-speed ferry service to Block Island, the company that owns the Block Island Ferry is seeking state permission to grow its own fast-ferry operation with a new 500-passenger ship.

Interstate Navigation, which runs the year-round traditional ferry to the island from the Port of Galilee, wants to replace its 250-passenger seasonal high-speed boat with a new $10.5-million vessel that can carry twice as many passengers. The new 500-passenger high-speed vessel, like Interstate's current fast ferry, would run during the warmer months between Galilee and Block Island's Old Harbor.

Ferry service to Block Island is tightly regulated by the Rhode Island Division of Public Utilities and Carriers, which needs to sign off on Interstate's plan to borrow $8.5 million for the new ferry. The Division has scheduled a meeting at 10 a.m. Thursday at its offices in Warwick to consider Interstate's request.

In written testimony to state regulators earlier this month, David Bebyn, an accountant working for Interstate, said demand for high-speed service last summer convinced the company it needed a bigger boat.

"The current fast ferry has many times during the summer period sold out, especially on weekends and holidays," Bebyn said. "Management has estimated that the new fast ferry would carry an additional 21,885 passengers."

Bebyn said if a new ferry is built, the current high-speed ferry making the Galilee-to-Block-Island run, the Athena, would be shifted to Interstate's high-speed Newport-to-Block-Island route. That, in turn, would free up a vessel Interstate could use to bid on the state-sponsored Providence to Newport ferry service, he added.

High-speed ferry service has been a contentious subject on Block Island for more than a decade.

Interstate opposed the initial launch of high-speed service between Block Island and Galilee in 2001, arguing that it would siphon summer tourists from the year-round traditional "lifeline" ferry that permanent residents depend on.

Interstate eventually took over the Galilee high-speed ferry and now says it subsidizes the traditional year-round "slow" ferry, keeping its rates down.

"This would be a benefit to the traditional ferry service because the fast-ferry service provides financial subsidy to the traditional service, which helps to hold down rates on the traditional year-round lifeline service," Bebyn told regulators in support of buying the new ferry.

But tensions bubbled up again in 2013 when Charles Donadio, the man behind that original high-speed service, proposed starting a new high-speed line from Quonset Business Park in North Kingstown to Block Island.

Fought by Interstate and the town of New Shoreham, Donadio's Rhode Island Fast Ferry application was finally approved in 2016, but opponents are now standing in the way of expanding the dock where the ferry would land. (The proposed dock off Ballard's hotel and tiki bar would also be used to service offshore wind farms, according to proponents.)

While Donadio expects his new ferry to be delivered in the spring, the fate of the dock is now in Superior Court.

Over the years, town officials have argued that another ferry docking in the Old Harbor would congest the small waterway while adding more tourists to an island "already saturated with people."

In support of Interstate buying a bigger high-speed ferry, Bebyn didn't address crowding in the harbor or on the island.