The master of a tank vessel having a COW system under Sec. 157.10(e), Sec. 157.10a(a)(2), or Sec. 157.10c(b)(2) shall ensure that each cargo tank that is crude oil washed during a voyage other than a ballast voyage--
(a) Remains empty so that the tank may be inspected upon arrival at the next discharge port; and
(b) If it is to be used as a ballast tank when leaving the discharge port, is ballasted before the vessel departs from that discharge port so that the tank may be inspected under Sec. 157.140(a)(2). [CGD 77-058b, 45 FR 43709, June 30, 1980, as amended by CGD 82-28, 50 FR 11628, Mar. 22, 1985]