While fast to a dock, a vessel during transfer of bulk cargo shall display a red flag by day or a red light by night, which signal shall be so placed that it will be visible on all sides. When at anchor, a vessel during transfer of bulk cargo shall display a red flag by day, placed so that it will be visible on all sides. This flag may be metallic.
source: CGFR 70-10, 35 FR 3714, Feb. 25, 1970, unless otherwise noted.
cite as: 46 CFR 151.45-9