ALCOAST 011/07 introduced the "Boonie" hat as organizational clothing for the operational environment.
"THE BOONIE HAT IS AUTHORIZED AS ORGANIZATIONAL CLOTHING FOR THE OPERATIONAL ENVIRONMENT ONLY, NOT TO BE WORN OFF BASE, WHEN INTERACTING WITH THE PUBLIC, OR BY LAW ENFORCEMENT OR BOARDING TEAM MEMBERS. ONLY SEW ON RANK INSIGNIA ARE AUTHORIZED PLACED IN THE CENTER OF THE FRONT SECTION."
The Auxiliary Manual, Ch. 10., D.3.f. Auxiliary Sun Hat (Tilley hat)
The Auxiliary sun hat is a dark blue wide-brimmed cotton hat, with the words ―"U.S. Coast Guard Auxiliary" embroidered in silver on the front. The sun hat may be worn in lieu of a ball cap when wearing Undress Blue Summer (Bravo), Working Blue, ODU, the Jump suit, Hot Weather uniform, or when on patrol or on VE missions (includes VSCs, personal watercraft (PWC) safety checks, and examinations of UTVs/UPVs/CFVs). The correct method of wearing the hat is with the brim down for maximum sun protection. No insignia may be worn on the hat. The AUXCEN carries the only hat authorized.