An advanced sonar system developed by FarSounder Inc. is being used in a new fleet of high-speed ferries commissioned by the San Francisco Bay Area Water Emergency Transportation Authority.

The first ferry, Gemini, was christened in December. Officials say the new vessels are the most environmentally friendly ferries in the country, and expect they will enhance their emergency-response capability and water-transit network.

Gemini’s exhaust is 10 times cleaner than the Bay Area’s existing ferries, they said.

The Gemini includes a FarSounder FS-3DT Forward Looking Sonar, one of the Warwick-based company’s newest products. The sonar generates a 3-D image that helps ships avoid obstacles. San Francisco authorities said the FS-3DT will help the new ferries avoid whale strikes.