California Code, Harbors and Navigation Code - HNC § 767

An operator's license issued by the department pursuant to the provisions of this article shall be valid for five years from the date of issuance or renewal and may be renewed every five years thereafter unless suspended or revoked pursuant to Section 768.  The department may adopt rules and regulations establishing the requirements for renewal of any license issued under this article, including therein requirements for acuity of vision, color sense and general physical condition.