Cal. VEH § 9915

(a) Whenever the title or interest of any owner or legal owner in or to a vessel numbered under this code passes to another otherwise than by a voluntary transfer, the new owner or legal owner may obtain a transfer of ownership upon application therefor and upon presentation of the last certificate of ownership and certificate of number issued for the vessel, if available, and any instruments or documents of authority or certified copies thereof as may be required by the department, or required by law, to evidence or effect a transfer of title or interest in or to chattels in such case.

(b) The department when satisfied of the genuineness and regularity of the transfer shall give notice by mail to the owner and legal owner of the vessel as shown by the records of the department and five days after the giving of the notice, if still satisfied of the genuineness and regularity of such transfer, shall transfer the ownership of the vessel accordingly and issue a new certificate of ownership and cerificate of number to the person or persons entitled thereto. Such notice shall not be required for an involuntary transfer when repossession involves a secured party.