Another day, another dubious plan by Team de Blasio to shell out millions — this time, on boats for the city’s ferry service.

As The Post’s Nolan Hicks reported Thursday, Blas & Co. want to sink $84.5 million more into the heavily subsidized water-transit system to buy 19 vessels from operator Hornblower. But City Comptroller Scott Stringer warns that “taxpayers are being taken for a ride” — and he’s blocking the deal.

“When you have big-ticket items like Renewal Schools, Thrive and now a bloated ferry contract, we need to raise the questions,” Stringer told The Post, referring to the mayor’s failed $773 million school-turnaround program and First Lady Chirlane McCray’s troubled $850 million mental-health initiative.

Already, the city has OK’d $582 million for six years of ferry service, which began in 2017. It claims buying the boats will save $140 million in usage fees over five years, yet the fees actually amount to less than $12 million. At that rate, it’ll take 35 years to recoup the boats’ $84.5 million cost.

The comptroller also worries that the city seems to be dealing solely with Hornblower, rather than looking for the best deal on the market. Plus, it’ll be stuck with the boats, having spent millions on them, even if service declines or ends.

Transit advocates, meanwhile, ask why the city is spending so much on ferries that serve a few million riders a year, instead of buses, which handle 2 million a day.

The latest Quinnipiac poll found nearly half of city voters, 48 percent, rate Mayor de Blasio negatively, while just 36 percent give him a thumbs-up. His team’s incompetence explains why.