33 CFR 64.23 : Navigation And Navigable Waters (§ 1.01-1 To Parts 404-499) — (§ 1.01-1 To Parts 121-124) — Coast Guard, Department Of Homeland Security (§ 1.01-1 To Parts 121-124) — Aids To Navigation (Part 60 To § 76.10-1) — Marking Of Structures, Sunken Vessels And Other Obstructions (§ 64.01 To § 64.33) — Structures (§ 64.21 And § 64.23) — Duration of marking on structures.