46 CFR § 31.10-20 - Definitions relating to hull examinations—T/B ALL.

---
identifier: "/us/cfr/t46/s31.10-20"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 31.10-20 - Definitions relating to hull examinations—T/B ALL."
title_number: 46
title_name: "Shipping"
section_number: "31.10-20"
section_name: "Definitions relating to hull examinations—T/B ALL."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "D"
subchapter_name: "TANK VESSELS"
part_number: "31"
part_name: "INSPECTION AND CERTIFICATION"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "33 U.S.C. 1321(j); 46 U.S.C. 2103, 3205, 3306, 3307, 3703; 46 U.S.C. Chapter 701; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; E.O. 12777, 56 FR 54757, 3 CFR, 1991 Comp., p. 351; DHS Delegation No. 00170.1, Revision No. 01.4. Section 31.10-21 also issued under the authority of Sect. 4109, Pub. L. 101-380, 104 Stat. 515."
regulatory_source: "CGFR 65-50, 30 FR 16662, Dec. 30, 1965, unless otherwise noted."
cfr_part: "31"
---


# 31.10-20 Definitions relating to hull examinations—T/B ALL.

As used in this part—

(a) *Drydock examination* means hauling out of a vessel or placing a vessel in a drydock or slipway for an examination of all accessible parts of the vessel's underwater body and all through-hull fittings.

(b) *Internal structural examination* means an examination of the vessel while afloat or in drydock and consists of a complete examination of the vessel's main strength members, including the major internal framing, the hull plating, voids, and ballast tanks, but not including cargo or fuel oil tanks.

(c) *Cargo tank internal examination* means an examination of the vessel while afloat or in drydock and consists of an examination of the internals of all cargo tanks; except, if the vessel is certificated to carry cargoes regulated under part 38 or subchapter O of this chapter, the cargo tank internal examination must be accomplished as specified in parts 38 and 151 of this chapter respectively.

(d) *Underwater survey* means the examination, while the vessel is afloat, of all accessible parts of the vessel's underwater body and all through-hull fittings.

[CGD 84-024, 52 FR 39649, Oct. 23, 1987, as amended by CGD 84-024, 53 FR 32229, Aug. 24, 1988; CGD 95-028, 62 FR 51197, Sept. 30, 1997]