The MTA on Wednesday announced increased capacity on the temporary ferry service planned for L-train commuters during a 15-month shutdown of the line’s tunnel that starts in April for repairs to damage from Superstorm Sandy.

The service will include two 240-passenger vessels that will provide up to 61 percent more capacity than the originally planned 149 passengers, the agency said.

The city’s Economic Development Corp. has tapped NY Waterway to operate the temporary service, which will be separate from NYC Ferry and run express from North Sixth Street in Williamsburg in Brooklyn to Stuyvesant Cove at East 20th Street and the FDR in Manhattan.

A third ferry also will be fully staffed and ready for immediate use if there is any interruption in service. This will allow for an hourly capacity of just under 2,000 passengers per direction.

Transit officials said the original capacity would have sufficed to serve the roughly 4 percent of L train straphangers expected to opt for the ferry instead of alternate subway or bus service.

“We only expect a small portion of our customers to choose a ferry over the subway or bus, but we’re keeping our promise to listen to your feedback and if any aspect of our alternate service plan needs tweaking, then we will do that,” subway system boss Andy Byford said in a statement.

Transportation Commissioner Polly Trottenberg said: “The closure of the L train tunnel will dramatically alter commuting routines for hundreds of thousands of New Yorkers.

“Along with increased subway service, alternative buses and better cycling connections, including expanded Citi Bike, MTA and DOT are working cooperatively to provide reliable travel alternatives to the L train across the East River,” she said.

The base fare on the ferry will be $2.75, and free transfers to other services will be available. The ferry will operate every 7 1/2 minutes during peak hours.

The affected subway line runs from Canarsie in Brooklyn to Eighth Avenue and 14th Street in Manhattan.