The search resumed on Monday for two adults and two children who called for help on their sinking sailboat about 65 miles off Monterey on Sunday.
A Coast Guard helicopter took off about 6:45 a.m. to look again for the four, including two children under 8, who reported their sailboat was sinking about 4:20 p.m. Sunday, according to Coast Guard Lt. Heather Lampert. She added that the boaters said their 29-foot sailboat was taking on water and their electronics were failing, and their boat may be called the Charmblow.
The four were originally thought to have gone missing off Half Moon Bay and are believed to be traveling south based on the flow of the current, Coast Guard officials said.
An hour later, the group reported that they were abandoning their boat. They didn't have life rafts so they were trying to make one out of a cooler and life preserver ring, Lampert said. It's unknown if they had life jackets.
The Coast Guard then lost radio contact with the group.
The National Weather Service had issued an advisory throughout the weekend warning boaters of strong winds and rough seas around the Bay Area.
Mariners "operating smaller vessels should avoid navigating in these conditions," the advisory said.
A search overnight, which included crews from the California Air National Guard, and Coast Guardsmen aboard a 210-foot cutter, yielded no results.
The Coast Guard is asking anyone with any information regarding the incident to notify the Coast Guard immediately at 415-399-3547.
NBC Bay Area's Bob Redell contributed to this report.