46 CFR 140.610: Hatches and other openings on towing vessels

Last reviewed: October 14, 2026

This section sets rules to limit down-flooding and progressive flooding on towing vessels. The master must make sure watertight and weather-tight openings work, and hatches and openings must be kept tightly closed except in listed cases. Watertight doors must be closed in operation, and exterior main deck openings must be closed when downstreaming.

Applies toAll towing vessels.

What it says

  1. All towing vessels must be operated in a manner that minimizes the risk of down-flooding and progressive flooding.

    46 CFR 140.610(a)“All towing vessels must be operated in a manner that minimizes the risk of down-flooding and progressive flooding.”

  2. The master must ensure that all hatches, doors, and other openings designed to be watertight or weather-tight function properly.

    46 CFR 140.610(b)“The master must ensure that all hatches, doors, and other openings designed to be watertight or weather-tight function properly.”

  3. The master or officer in charge of a navigational watch must ensure all hatches and openings of the hull and deck are kept tightly closed, except in the cases listed in paragraph (c).

    46 CFR 140.610(c)“The master or officer in charge of a navigational watch must ensure all hatches and openings of the hull and deck are kept tightly closed except:”

  4. A hatch or opening may be open when access is needed through the opening for transit.

    46 CFR 140.610(c)(1)“When access is needed through the opening for transit;”

  5. When operating on rivers with a tow, openings may be open if the master determines the safety of the vessel is not compromised.

    46 CFR 140.610(c)(2)“When operating on rivers with a tow, if the master determines the safety of the vessel is not compromised; or”

  6. On lakes, bays, and sounds, openings may be open only when the vessel is without a tow during calm weather and the master determines that the safety of the vessel is not compromised.

    46 CFR 140.610(c)(3)“When operating on lakes, bays, and sounds, without a tow during calm weather, and only if the master determines that the safety of the vessel is not compromised.”

  7. Where installed, all watertight doors in watertight bulkheads must be closed during operation of the vessel, unless they are being used for transit between compartments.

    46 CFR 140.610(d)“Where installed, all watertight doors in watertight bulkheads must be closed during the operation of the vessel, unless they are being used for transit between compartments;”

  8. When downstreaming, all exterior openings at the main deck level must be closed.

    46 CFR 140.610(e)“When downstreaming, all exterior openings at the main deck level must be closed.”

Common questions

When can hatches be open on a towing vessel?

Hatches and openings must be kept tightly closed except for transit access, on rivers with a tow if the master determines safety is not compromised, or on lakes, bays, and sounds without a tow in calm weather if the master so determines.

“The master or officer in charge of a navigational watch must ensure all hatches and openings of the hull and deck are kept tightly closed except:”

Do watertight doors have to stay closed while a towing vessel operates?

Yes, where installed, watertight doors in watertight bulkheads must be closed during operation. They may be open only while used for transit between compartments.

“Where installed, all watertight doors in watertight bulkheads must be closed during the operation of the vessel, unless they are being used for transit between compartments;”

What must be closed when downstreaming?

When downstreaming, all exterior openings at the main deck level must be closed.

“When downstreaming, all exterior openings at the main deck level must be closed.”

The text of 46 CFR 140.610

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

Hatches and other openings

(a) All towing vessels must be operated in a manner that minimizes the risk of down-flooding and progressive flooding.

(b) The master must ensure that all hatches, doors, and other openings designed to be watertight or weather-tight function properly.

(c) The master or officer in charge of a navigational watch must ensure all hatches and openings of the hull and deck are kept tightly closed except:

(1) When access is needed through the opening for transit;

(2) When operating on rivers with a tow, if the master determines the safety of the vessel is not compromised; or

(3) When operating on lakes, bays, and sounds, without a tow during calm weather, and only if the master determines that the safety of the vessel is not compromised.

(d) Where installed, all watertight doors in watertight bulkheads must be closed during the operation of the vessel, unless they are being used for transit between compartments; and

(e) When downstreaming, all exterior openings at the main deck level must be closed.

(f) Decks and bulkheads designed to be watertight or weathertight must be maintained in that condition.

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.