A proposal to use local money to ferry workers to MacDill Air Force Base in Tampa always has been a questionable idea. The loss of nearly $5 million in federal money toward the project makes it all the more suspect. Itís time the ferry supporters offer a plan that makes sense or abandon ship. They also need to justify spending tens of millions of public dollars on a ferry that may or may not be of much use to the general public.Leaders at Hillsborough Area Regional Transit acknowledged this week that delays with the ferry project resulted in the loss of a $4.7 million federal grant. That money was secured in 2014 with the help of U.S. Rep. Kathy Castor, D-Tampa, and intended for construction of a launch site. But the project stalled for years over environmental concerns, red tape associated with the grant, controversy over placing the boat launch near Apollo Beach and funding shortfalls. HARTís announcement was hardly news; county commissioners directed the staff in February 2017 to explore forgoing the grant and self-funding the ferry, saying it might expedite the service.Four years is plenty of time to make a compelling case that this is a worthy project. The ferry would run from south county, where many MacDill workers reside, to the base. The developers once estimated it would carry 1,500 passengers a day, which sounds optimistic. While service would be restricted to those with access to a military base, supporters say the broader public benefit would be in removing traffic congestion from area roads at peak times. And some supporters frame the plan as virtually free, given that the county set aside $22 million to pay for the project through money it obtained from the BP oil spill settlement.Tampa attorney Ed Turanchik, who represents the companies involved in the public-private venture, HMS Global Maritime and South Swell, said this week the countyís use of local money will put the project on a faster track. He estimates his group will present several site options with cost estimates, business plans and ridership projections to the county by January, and include provisions for service for the general public between Tampa and St. Petersburg. He also said the project could again pursue federal funding later.The refined proposals need to make business sense and show strong ridership figures. They also should explain why county dollars should be going to provide a closed transit loop for employees assigned to a U.S. military base. In the grand scheme of things, $22 million is not much to pay for the capital costs of a new transit system. But shuttling one group of workers around is a low priority for local transit dollars. This project could still face a multi-million dollar funding gap. And using settlement money from an environmental disaster to ferry suburban residents to work hardly seems in line with the purpose of the settlement.Water is an incredible asset for the Tampa Bay area to leverage for its transportation needs. But local governments have to be smart in using their limited resources. If this is the best use of the BP settlement, or any other public money, then the supporters need to offer more specifics and a clear timetable for the project to start. The county has already paid or pledged nearly $500,000 to examine this venture. Itís time to decide whether it deserves any more interest or public money.