The agency believes the boat may have been called "Charmblow." In the crackling recording, a man's voice is heard saying, "Coast Guard, Coast Guard, we are abandoning ship. This is the (Charmblow), we are abandoning ship."
The agency has not identified the family, although investigators were able to determine from the broken distress calls that they were a husband and wife, their 4-year-old son and his cousin, Lampert said.
The family's location initially was reported farther north, but Lampert said investigators using the boat's radio signal and radar now believe the call came in west of Monterey Bay, which is about 100 miles south of San Francisco. The boat did not have a working GPS system.
The National Weather Service had issued an advisory throughout the weekend warning boaters of strong winds and rough seas around the San Francisco Bay Area. Water temperatures in the area typically are in the 40s and 50s, making long-term survival difficult.
Mariners "operating smaller vessels should avoid navigating in these conditions," the advisory said.
Calls to harbors in California have failed to locate the boat, and database searches have come up empty too, Lampert said. The Coast Guard was expanding its search to Hawaii, the Seattle area and north into Canada.