RCW 48.12.050

With reference to marine and transportation insurances, premiums on trip risks not terminated shall be deemed unearned and the commissioner may require the insurer to carry a reserve thereon equal to one hundred percent on trip risks written during the month ended as of the date of statement; and computed upon a pro rata basis or, with the commissioner's consent, in accordance with the alternative methods provided in RCW 48.12.040 for all other risks.