California Code, Revenue and Taxation Code - RTC § 6368.1

(a) There are exempted from the taxes imposed by this part, the gross receipts from the sale of and the storage, use, or other consumption in this state of watercraft which are leased, or are sold to persons for the purpose of leasing, and any sales of tangible personal property becoming a component part of such watercraft in the course of constructing, repairing, cleaning, altering, or improving the same, and charges made for labor and services rendered in respect to such constructing, repairing, cleaning, altering, or improving, if any of the following conditions are met:

(b) For purposes of this section, it shall be rebuttably presumed that a person is not regularly engaged in the business of commercial deep sea fishing if the person has gross receipts from commercial fishing operations of less than twenty thousand dollars ($20,000) a year.

(c) For purposes of this section, it shall be rebuttably presumed that the watercraft is not regularly used in the business of transporting for hire property or persons, if the yearly gross receipts of the lessor from the lease of that watercraft to persons using that watercraft in the transportation of property or persons do not exceed 10 percent of the cost of that watercraft to the lessor, or twenty-five thousand dollars ($25,000), whichever is less.