The Superferry is long gone, but clearly not forgotten.

Gov. David Ige has not forgotten, and would like at least to explore the possibility of bringing back an interisland ferry.

It was surprising that such a proposal was floated as a separate initiative, without even a hint of it in Ige’s recent State of the State address.

But the notion of reviving a service like Superferry is one that’s worth considering. The state should vet all the issues with far greater deliberation than was done before a Hawaii Supreme Court environmental ruling effectively drove the company to bankruptcy in 2009.

The exploration effort was assigned to the state Department of Transportation. DOT Director Ford Fuchigami told lawmakers Wednesday that the state will put out a request for proposals later this year, so a new feasibility study could be done.

Among all the question marks hanging over the proposal, the one that deserves particular scrutiny is its financial plan. The Ige administration envisions the project as a state-owned system that could qualify for federal subsidies.

Notwithstanding any aid from Uncle Sam on this project, it will certainly take a big bite out the state budget to operate, and the impact on the state’s overburdened taxpayers needs to be laid out clearly.

Private ownership of the service — or at least private partners sharing in the costs — should be examined as alternatives. The Superferry was a private concern, after all, so the full public investment should not be viewed as the only alternative.

About $40 million in public funds were invested in making harbor improvements to accommodate the Superferry, which launched with two ships, the Alakai and the Huakai, in 2007.

But the administration of then-Gov. Linda Lingle proceeded without doing a full environmental impact statement, a decision that proved fateful. Community and environmentalist groups protested vigorously.

The courts ultimately found that an EIS was required, agreeing with arguments from the Sierra Club and other plaintiffs that concerns about issues such as invasive species merited the complete study. The Legislature passed a law, tailored to the Superferry, to enable service to continue while the EIS was prepared. That law was struck down, and the service was halted.

Many of the concerns were legitimate. Invasive species control is a challenge for the state, and the transport of passengers with their vehicles on a regular basis did present a threat the state would have to reckon with.

The economics of running a ferry service over significant distances, compounded by Hawaii’s overall high business costs, adds to the difficulties.

However, there also are factors that would support the establishment of a ferry service.

It would add competition to the interisland travel marketplace, giving travelers — visitors and residents alike — a choice when planning trips to other islands.

It would enable interisland commerce to happen more organically. Small farmers on one island would find it easier and cheaper to bring their produce to larger markets, on Oahu or elsewhere.

Finally, a ferry would connect families that are scattered among the islands, a unifying element for the state that would be healthy and provide more opportunities for Hawaii residents.

The two ships built for the service, now Navy-owned, were renamed the USNS Guam and the USNS Puerto Rico. Fuchigami plans to investigate the potential for recovering these ships next month during a trip to Washington, D.C. Senate Transportation and Energy Committee Chairwoman Lorraine Inouye said she plans to go along with him.

Whether or not such travel at this stage is necessary is unclear, but some fact-finding is undeniably necessary before the state commits to this venture.

Fuchigami told legislators that the effort would take years, adding that “we need to do it right this time.”

That’s a given. The question that should be answered first is, “Should Hawaii do it at all?”