33 CFR 151.23: Coast Guard inspection and detention of ships

Last reviewed: October 14, 2026

This section says a ship at a port or terminal under U.S. jurisdiction is subject to Coast Guard inspection of its oil pollution certificates, equipment and discharges. A noncompliant ship may be detained by order of the COTP or OCMI. An inspection may include the Oil Record Book and the oil content meter continuous records.

Applies toShips at a port or terminal under the jurisdiction of the United States.

What it says

  1. A ship at a port or terminal under U.S. jurisdiction is subject to Coast Guard inspection to determine that a valid IOPP Certificate is on board and that the ship and its equipment correspond substantially with the certificate's particulars.

    33 CFR 151.23(a)(1)“To determine that a valid IOPP Certificate is on board and that the condition of the ship and its equipment corresponds substantially with the particulars of the IOPP Certificate;”

  2. A ship is subject to inspection to determine that evidence of compliance with MARPOL 73/78, as required by § 151.21, is on board and that the condition of the ship and its equipment corresponds substantially with the particulars of that evidence.

    33 CFR 151.23(a)(2)“To determine that evidence of compliance with MARPOL 73/78, as required by § 151.21 is on board and that the condition of the ship and its equipment corresponds substantially with the particulars of this evidence of compliance;”

  3. A ship is subject to inspection to determine whether it has operated in accordance with MARPOL 73/78 or this subchapter and has not discharged oil or oily mixtures in violation of them.

    33 CFR 151.23(a)(3)“To determine whether a ship has been operating in accordance with and has not discharged any oil or oily mixtures in violation of the provisions of MARPOL 73/78 or this subchapter;”

  4. A ship is subject to inspection to investigate a discharge anywhere, when a party to MARPOL 73/78 requests it and has furnished sufficient evidence to support a reasonable belief that a discharge has occurred.

    33 CFR 151.23(a)(4)“upon request from a party to MARPOL 73/78 for an investigation when the requesting party has furnished sufficient evidence to support a reasonable belief that a discharge has occurred.”

  5. The COTP or OCMI may detain a noncompliant ship at the port or terminal where the violation is discovered until, in the detaining authority's opinion, it can proceed to sea without presenting an unreasonable threat of harm to the marine environment.

    33 CFR 151.23(b)“may be detained by order of the COTP or OCMI, at the port or terminal where the violation is discovered”

  6. The detention order may authorize the ship to go to the nearest appropriate available shipyard instead of staying where the violation was discovered.

    33 CFR 151.23(b)“The detention order may authorize the ship to proceed to the nearest appropriate available shipyard rather than remaining at the place where the violation was discovered.”

  7. An inspection may include examining the Oil Record Book, the oil content meter continuous records, and a general examination of the ship.

    33 CFR 151.23(c)“An inspection under this section may include an examination of the Oil Record Book, the oil content meter continuous records, and a general examination of the ship.”

  8. A copy of any Oil Record Book entry may be made, and the Master may be required to certify that the copy is a true copy of the entry.

    33 CFR 151.23(c)“A copy of any entry in the Oil Record Book may be made and the Master of the ship may be required to certify that the copy is a true copy of such entry.”

Common questions

Can the Coast Guard detain a ship for oil pollution violations?

Yes. The COTP or OCMI may detain a ship that does not comply, or whose condition does not substantially agree with its IOPP Certificate or other required documentation, at the port or terminal where the violation is discovered.

“may be detained by order of the COTP or OCMI, at the port or terminal where the violation is discovered”

What may the Coast Guard examine during an oil pollution inspection?

An inspection may include the Oil Record Book, the oil content meter continuous records, and a general examination of the ship.

“An inspection under this section may include an examination of the Oil Record Book, the oil content meter continuous records, and a general examination of the ship.”

Can a detained ship go to a shipyard?

Yes. The detention order may authorize the ship to proceed to the nearest appropriate available shipyard rather than remaining where the violation was discovered.

“The detention order may authorize the ship to proceed to the nearest appropriate available shipyard rather than remaining at the place where the violation was discovered.”

Can the Master be required to certify Oil Record Book copies?

Yes. A copy of any entry may be made, and the Master may be required to certify that the copy is a true copy of the entry.

“A copy of any entry in the Oil Record Book may be made and the Master of the ship may be required to certify that the copy is a true copy of such entry.”

The text of 33 CFR 151.23

Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR

Inspection for compliance and enforcement

(a) While at a port or terminal under the jurisdiction of the United States, a ship is subject to inspection by the Coast Guard—

(1) To determine that a valid IOPP Certificate is on board and that the condition of the ship and its equipment corresponds substantially with the particulars of the IOPP Certificate;

(2) To determine that evidence of compliance with MARPOL 73/78, as required by § 151.21 is on board and that the condition of the ship and its equipment corresponds substantially with the particulars of this evidence of compliance;

(3) To determine whether a ship has been operating in accordance with and has not discharged any oil or oily mixtures in violation of the provisions of MARPOL 73/78 or this subchapter;

(4) To determine whether a ship has discharged oil or oily mixtures anywhere in violation of MARPOL 73/78, upon request from a party to MARPOL 73/78 for an investigation when the requesting party has furnished sufficient evidence to support a reasonable belief that a discharge has occurred.

(b) A ship that does not comply with the requirements of parts 151, 155 and 157 of this chapter, or where the condition of the ship or its equipment does not substantially agree with the particulars of the IOPP Certificate or other required documentation, may be detained by order of the COTP or OCMI, at the port or terminal where the violation is discovered until, in the opinion of the detaining authority, the ship can proceed to sea without presenting an unreasonable threat of harm to the marine environment. The detention order may authorize the ship to proceed to the nearest appropriate available shipyard rather than remaining at the place where the violation was discovered.

(c) An inspection under this section may include an examination of the Oil Record Book, the oil content meter continuous records, and a general examination of the ship. A copy of any entry in the Oil Record Book may be made and the Master of the ship may be required to certify that the copy is a true copy of such entry.

Sections it refers to

The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.