Add another item to Google's (GOOG) long list of employee perks: ferry service.

The Internet company has launched a free service aboard an 83-foot, Wi-Fi-equipped catamaran to carry some of its workers on their daily commute between San Francisco and the South Bay.

None of its rivals have announced similar plans. But Google is hoping to defuse a simmering controversy over the high-end charter buses that several major tech companies use to shuttle thousands of employees to work in Silicon Valley from San Francisco and the East Bay.

Google's chartered ferry, a "hydrofoil-assisted catamaran" with a cruising speed of 27 knots, can carry up to 150 passengers. It's been less than full on its initial round trips between San Francisco's ferry terminal and the Port of Redwood City, where employees can hop a private bus to the nearby Google campus in Mountain View.

"They're going to see if this is something their employees want, and if it makes economic and logistical sense," said Peter Dailey, maritime director for the Port of San Francisco, which operates the terminal used by the Google ferry and other charter services.

Google, Apple (AAPL), Facebook, Yahoo (YHOO) and Genentech agreed earlier this week to pay up to $1.5 million in user fees after San Francisco residents complained that the companies' private buses are clogging city streets and blocking access to public transit stops.

"We certainly don't want to cause any inconvenience to SF residents and we're trying alternative ways to get Googlers to work," a Google representative said Wednesday, in the company's only statement on the ferry service.

Tech companies say their buses keep thousands of cars off Highway 101 each day, by shuttling valley workers who prefer to live in San Francisco's trendy neighborhoods. But the buses have been picketed by activists who say they're symbols of an economic divide, in which young, affluent tech workers are driving up rents and displacing longtime, lower-income residents.

Google made headlines last fall with another maritime venture -- a mysterious barge that the company is outfitting as a giant floating showroom for new technology. That's a separate project, which officials say has been delayed by permit issues.

The giant Internet company is now testing the waters with the ferry: Port officials said a Google contractor took out permits to operate the passenger service for just 30 days, with two runs every weekday morning from San Francisco to Redwood City and two return trips every evening.

While the boat known as "Triumphant" has only carried 30 to 40 passengers on some initial trips, the service could catch on: The leased boat was designed for high-end ferry service and dinner cruises, with large comfortable decks fore and aft, and a sizable cabin fitted with tables and chairs.

Ferries are a daily habit for some commuters in Marin County and the East Bay, but there hasn't been regular service to the South Bay in years. A Redwood City port official said the Google boat is the first passenger ferry to use his facility, which usually hosts commercial freighters, pleasure boats and occasional excursion tours.

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