Cal. Harbors and Navigation Code § 716

(a) No broker shall engage in any transaction for which a license is required under this article without first obtaining a signed written authorization to do so from the broker’s principal. An authorization to sell shall contain a description of the vessel, including the undocumented vessel’s registration number or the name, official number, and home port if the vessel is documented with a federal agency. The written authorization shall also state the type of listing, the gross listing price, the agreed upon commission or other compensation of the broker, and any repairs authorized to be made. (b) An offer to purchase shall contain the description of the yacht, including the undocumented vessel’s registration number or the name, official number, and home port if the vessel is documented with a federal agency. The written authorization to purchase shall also state the amount of deposit, terms of the sale, and any contingencies or conditions under which a deposit shall not be returned if the sale is not completed. (c) When a broker prepares, or there is prepared on behalf of a broker, a written authorization to sell or purchase, the broker shall deliver a copy of the written authorization to the person executing it. Receipt of the copy shall be made on the face of the original written authorization.