33 CFR 151.2005: Definitions for ballast water subpart

Last reviewed: October 14, 2026

This section defines terms used in this subpart. It first adopts definitions from other named sources, unless this section says otherwise. It then defines terms such as Captain of the Port, exchange, seagoing vessel and voyage.

What it says

  1. Unless this section says otherwise, the definitions in 33 CFR 151.1504, 33 CFR 160.202, and the United Nations Convention on the Law of the Sea apply to this subpart.

    33 CFR 151.2005(a)“Unless otherwise stated in this section, the definitions in 33 CFR 151.1504, 33 CFR 160.202, and the United Nations Convention on the Law of the Sea apply to this subpart.”

  2. A vessel is "constructed" at a stage when its keel is laid, when construction identifiable with the specific vessel begins, when assembly has commenced and comprises at least 50 tons or 1 percent of the estimated mass of all structural material, whichever is less, or when it undergoes a major conversion.

    33 CFR 151.2005(b)“Assembly of the vessel has commenced and comprises at least 50 tons or 1 percent of the estimated mass of all structural material, whichever is less; or”

  3. Flow-through exchange means flushing out ballast water by pumping in mid-ocean water at the bottom of the tank and continuously overflowing the tank from the top until three full volumes of water has been changed.

    33 CFR 151.2005(b)“flush out ballast water by pumping in mid-ocean water at the bottom of the tank and continuously overflowing the tank from the top until three full volumes of water has been changed”

  4. Empty/refill exchange means pumping out ballast water taken on in ports, estuarine, or territorial waters until the pumps lose suction, then refilling the tanks with mid-ocean water.

    33 CFR 151.2005(b)“pump out the ballast water taken on in ports, estuarine, or territorial waters until the pump(s) lose suction, then refilling the ballast tank(s) with mid-ocean water.”

  5. A port or place of departure is any port or place in which a vessel is anchored or moored.

    33 CFR 151.2005(b)“Port or place of departure means any port or place in which a vessel is anchored or moored.”

  6. A seagoing vessel is a vessel in commercial service that operates beyond the boundary line established by 46 CFR part 7. It does not include a vessel that navigates exclusively on inland waters.

    33 CFR 151.2005(b)“a vessel in commercial service that operates beyond the boundary line established by 46 CFR part 7. It does not include a vessel that navigates exclusively on inland waters.”

  7. A voyage is any transit by a vessel destined for any United States port or place.

    33 CFR 151.2005(b)“Voyage means any transit by a vessel destined for any United States port or place.”

Common questions

What is a seagoing vessel under 33 CFR 151.2005?

A seagoing vessel is a vessel in commercial service that operates beyond the boundary line established by 46 CFR part 7. It does not include a vessel that navigates exclusively on inland waters.

“a vessel in commercial service that operates beyond the boundary line established by 46 CFR part 7. It does not include a vessel that navigates exclusively on inland waters.”

What does empty/refill exchange mean for ballast water?

It means pumping out ballast water taken on in ports, estuarine, or territorial waters until the pumps lose suction. The tanks are then refilled with mid-ocean water.

“pump out the ballast water taken on in ports, estuarine, or territorial waters until the pump(s) lose suction, then refilling the ballast tank(s) with mid-ocean water.”

What counts as the United States in this subpart?

The States, the District of Columbia, Guam, American Samoa, the Virgin Islands, the Commonwealth of Puerto Rico, the Commonwealth of the Northern Mariana Islands, and any other territory or possession over which the United States exercises sovereignty.

“United States means the States, the District of Columbia, Guam, American Samoa, the Virgin Islands, the Commonwealth of Puerto Rico, the Commonwealth of the Northern Mariana Islands,”

The text of 33 CFR 151.2005

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

Definitions

(a) Unless otherwise stated in this section, the definitions in 33 CFR 151.1504, 33 CFR 160.202, and the United Nations Convention on the Law of the Sea apply to this subpart.

(b) As used in this subpart:

Captain of the Port (COTP) means the Coast Guard officer designated by the Commandant to command a COTP Zone as described in part 3 of this chapter.

Constructed in respect of a vessel means a stage of construction when—

(1) The keel of a vessel is laid;

(2) Construction identifiable with the specific vessel begins;

(3) Assembly of the vessel has commenced and comprises at least 50 tons or 1 percent of the estimated mass of all structural material, whichever is less; or

(4) The vessel undergoes a major conversion.

Exchange means to replace the water in a ballast tank using one of the following methods:

(1) Flow-through exchange means to flush out ballast water by pumping in mid-ocean water at the bottom of the tank and continuously overflowing the tank from the top until three full volumes of water has been changed to minimize the number of original organisms remaining in the tank.

(2) Empty/refill exchange means to pump out the ballast water taken on in ports, estuarine, or territorial waters until the pump(s) lose suction, then refilling the ballast tank(s) with mid-ocean water.

National Ballast Information Clearinghouse (NBIC) means the National Ballast Information Clearinghouse operated by the Coast Guard and the Smithsonian Environmental Research Center as mandated under the National Invasive Species Act of 1996.

Port or place of departure means any port or place in which a vessel is anchored or moored.

Port or place of destination means any port or place to which a vessel is bound to anchor or moor.

Seagoing vessel means a vessel in commercial service that operates beyond the boundary line established by 46 CFR part 7. It does not include a vessel that navigates exclusively on inland waters.

Shipboard Technology Evaluation Program (STEP) means a Coast Guard research program intended to facilitate research, development, and shipboard testing of effective BWMS. STEP requirements are located at:http://www.dco.uscg.mil/Our-Organization/Assistant-Commandant-for-Prevention-Policy-CG-5P/Commercial-Regulations-standards-CG-5PS/office-oes/.

United States means the States, the District of Columbia, Guam, American Samoa, the Virgin Islands, the Commonwealth of Puerto Rico, the Commonwealth of the Northern Mariana Islands, and any other territory or possession over which the United States exercises sovereignty.

Voyage means any transit by a vessel destined for any United States port or place.

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.