California Code, Harbors and Navigation Code - HNC § 773.6

An operator, or the operator's employee or agent, who directs the passengers to the life preservers while announcing that the passengers are required for their safety to don them shall be deemed to have complied with Section 773.5, if the operator, or the operator's employee or agent, or the operator's employee at least once instructs any passenger who fails to don a life preserver to do so, and if the life preservers are unwrapped, ready to be donned, and stowed in a conveniently accessible place.