TAMPA — Commuters and day-trippers will cruise between the downtowns of St. Petersburg and Tampa this fall at 33 mph on a 98-foot, 149-passenger catamaran, under plans unveiled Wednesday for what has been formally dubbed "the Cross-Bay Ferry."

"I challenge you to name any other world-class market across the country, and across the world, and not see this kind of service," said Chris Steinocher, president and chief executive of the St. Petersburg Area Chamber of Commerce. "Our visitors demand this kind of opportunity. They want to be on the water. You can see the water, and we've been teasing people. Now we have the opportunity to live up to what we believe our promise is — which is the best community on the water in the country."

Details of the service were unveiled at a news conference at Schifino Lee Advertising & Branding, one of two agencies handling marketing for the project.

"It's an on-the-water destination experience that will transform people's perception of Tampa Bay," said Ben Lee, principal of the firm. "The Cross-Bay Ferry will connect Beach Drive in St. Petersburg to the Riverwalk in downtown Tampa and all the great things that each of those destinations offer — the shopping, the dining, the museum, the hotels."

The ferry is a collaboration of the two cities, along with Pinellas and Hillsborough counties. The governmental bodies of each voted this summer to kick in $350,000, or a quarter of the $1.4 million cost of a six-month pilot program.

Seattle-based HMS Ferries is providing the vessel, the Provincetown IV. It has been ferrying passengers between Boston and Provincetown, Mass., during the summer months and will arrive in late October.

Organizers said the public will have several days to try the ferry for free during Thanksgiving week. The regular fare will be $10 for a one-way trip, $8 for ages 3 through 12, and free for children under 3. There will be reduced pricing for commuters. The trip will take 50 minutes each way.

Ed Turanchik, a longtime public transit advocate in the Tampa Bay area, said the ferry schedule will link with trolley services on the St. Petersburg side and the streetcar and Downtowner shuttle service in Tampa. "What's exciting about this is great first-mile/last-mile connectivity," Turanchik said. "There's ample parking. So we are going to have a multimodal transportation system involving water transportation starting this November, and that's going to be exciting."

The website CrossBayFerry.com is now active. According to the ferry timeline, which is subject to change, online ticket sales will commence on Oct. 15.

An inaugural VIP launch trip is planned for early November.

From Nov. 3 to Nov. 18, community and business organizations can experience the trip through a series of "Test the Waters" excursions.

Friday-Saturday-Sunday service, serving the entertainment, sports, shopping and tourism markets, begins Nov. 4, with Monday-Thursday service serving the commuter and tourist market launching the week of Nov. 28.

The twin-hull aluminum catamaran is designed for exceptionally smooth runs. In St. Petersburg, it will dock in the yacht basin along Bayshore Drive NE, while in Tampa, it will dock adjacent to the Tampa Convention Center.

There will be food and beverage service, bicycle racks, and indoor and outdoor seating.

The Provincetown IV is on loan, which limits the length of the test program from Nov. 1 through April 30. The local governments and HMS said they will measure demand for both commuter and noncommuter services and impact on vehicle use.

"Everywhere I go, people ask me about the ferry," said St. Petersburg Mayor Rick Kriseman, an early supporter of the project. "The Cross-Bay Ferry is a fantastic example of regional collaboration to take on an important challenge — transportation — in a way that's exciting to experience and pays homage to our maritime history. Importantly, this is a test project, and we need the community to support this if we want it to continue and expand."

Contact Jerome R. Stockfisch at jstockfisch@tampabay.com.