NVIC 11-93: Tonnage measurement systems for U.S. flag vessels

Last reviewed: October 14, 2026

This Circular is Coast Guard guidance on applying tonnage measurement systems to U.S. flag vessels. It replaces NVIC 11-93, Change 2. It lists the changes made, including that recent SOLAS amendments must be applied using convention measurement system tonnages.

Applies toThis NVIC applies to all U.S. flag vessels for which the application of a law of the United States depends on the vessel's tonnage.

What it says

  1. This Circular gives requirements on how tonnage measurement systems apply to U.S. flag vessels, and it replaces NVIC 11-93, Change 2.

    “This Circular provides requirements regarding the applicability of tonnage measurement systems to U.S. flag vessels. It replaces NVIC 11-93, Change 2.”

  2. Recent SOLAS amendments must be applied using convention measurement system tonnages, regardless of the vessel's keel laid or substantial alteration date.

    NVIC 11-93 a.“recent amendments to the International Convention for the Safety of Life at Sea (SOLAS) must be applied using convention measurement system tonnages, regardless of the vessel’s keel laid or substantial alteration date.”

  3. The ISM Code and ISPS Code tonnage-based requirements are included in the rule that SOLAS amendments use convention measurement system tonnages.

    NVIC 11-93 a.“This includes tonnage-based requirements of the International Management Code for the Safe Operation of Ships and for Pollution Prevention (ISM Code), and the International Code for Ship and Port Facility Security (ISPS Code).”

  4. Using regulatory measurement system tonnages for STCW purposes is no longer authorized.

    NVIC 11-93 b.“use of regulatory measurement system tonnages for this purpose is no longer authorized.”

  5. Any recreational or non-self-propelled vessel is eligible to be assigned optional regulatory measurement system tonnages under the simplified measurement system.

    NVIC 11-93 e.“any recreational or non-self-propelled vessel is eligible to be assigned optional regulatory measurement system tonnages under the simplified measurement system.”

  6. The tonnage grandfathering provisions of the 1969 Tonnage Convention apply only to requirements of conventions that were in effect on July 18, 1982.

    NVIC 11-93 g.“tonnage grandfathering provisions of the International Convention on Tonnage Measurement of Ships, 1969 apply only to requirements of conventions that were in effect on July 18, 1982.”

Common questions

Which vessels does NVIC 11-93 apply to?

It applies to all U.S. flag vessels for which the application of a law of the United States depends on the vessel's tonnage.

“This NVIC applies to all U.S. flag vessels for which the application of a law of the United States depends on the vessel's tonnage.”

Which tonnages apply to SOLAS amendments under NVIC 11-93?

Recent SOLAS amendments must be applied using convention measurement system tonnages. This holds regardless of the vessel's keel laid or substantial alteration date.

“must be applied using convention measurement system tonnages, regardless of the vessel’s keel laid or substantial alteration date.”

Can regulatory measurement system tonnages still be used for STCW?

No. The Circular says use of regulatory measurement system tonnages for this purpose is no longer authorized.

“use of regulatory measurement system tonnages for this purpose is no longer authorized.”

Does Change 3 replace an earlier version of NVIC 11-93?

Yes. It replaces NVIC 11-93, Change 2.

“It replaces NVIC 11-93, Change 2.”

The text of NVIC 11-93

U.S. Coast Guard, NVIC 11-93 (main body; enclosures not shown)

Ch-3 to 11-93, Applicability of Tonnage Measurement Systems to U.S. Flag Vessels

Commandant 400 7th Street, S.W. United States Coast Guard Washington, DC 20590-0001 Staff Symbol: MSC www.uscg.mil/hq/msc Phone: (202) 366-6481 FAX: (202) 366-3877 EMAIL: ec@msc.uscg.mil COMDTPUB P16700.4 NVIC 11-93, CH-3 NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 11-93, CHANGE 3 Subj: CH-3 TO NVIC 11-93, APPLICABILITY OF TONNAGE MEASUREMENT SYSTEMS TO U.S. FLAG VESSELS

Ch-3 to 11-93, Applicability of Tonnage Measurement Systems to U.S. Flag Vessels — PURPOSE. This Circular provides requirements regarding the applicability of tonnage

measurement systems to U.S. flag vessels. It replaces NVIC 11-93, Change 2.

Ch-3 to 11-93, Applicability of Tonnage Measurement Systems to U.S. Flag Vessels — DISCUSSION. The principal differences between this Circular and NVIC 11-93, Change 2 are

as follows: a. Changes have been made to reflect that recent amendments to the International Convention for the Safety of Life at Sea (SOLAS) must be applied using convention measurement system tonnages, regardless of the vessel’s keel laid or substantial alteration date. This includes tonnage-based requirements of the International Management Code for the Safe Operation of Ships and for Pollution Prevention (ISM Code), and the International Code for Ship and Port Facility Security (ISPS Code). b. References to applying the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) using a vessel's regulatory measurement system tonnages have been deleted. With the full coming into force of the 1995 Amendments to STCW on February 1, 2002, and as provided for in Appendix 4A of IMO Resolution A.882(21), Amendments to the Procedures for Port State Control

(Resolution A.787(19)), dated February 4, 2000, use of regulatory measurement system tonnages for this purpose is no longer authorized. c.

References have been deleted to the radiotelephony requirements of IMO Resolution A.494(XII), Revised Interim Scheme for Tonnage Measurement for Certain Ships.

These requirements are no longer applicable due to revisions to SOLAS that implemented the Global Maritime Distress and Safety System (GMDSS). a b c d e f g h I j k l m n o p q r s t u v w x y z A B * 1 1 1 1 C 1 1 1 1 D 1 1 E 1 1 F G H NON-STANDARD DISTRIBUTION: B:a Commandant (G-MOC, G-MO-1, G-MSE, G-MSO, G-MW, NMC, NVDC) (1) NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 11-93, CH-3 d.

All tables have been updated to reflect that Certificates of Documentation (COD's) generated by the Marine Information for Safety and Law Enforcement (MISLE) system show all tonnages assigned to a vessel, rather than just the "registered" tonnages.

Requirements formerly associated with the "Documentation" sections have been relocated to other sections, as appropriate. e.

Corrections have been incorporated to reflect that any recreational or non-self-propelled vessel is eligible to be assigned optional regulatory measurement system tonnages under the simplified measurement system. f.

Requirements regarding International Tonnage Certificates (1969) have been removed from all tables and included instead in the section "Definitions of Terms and Acronyms." Requirements on International Tonnage Certificates became more uniform after July 18, 1994, eliminating the need to address these requirements separately in the individual tables. g.

Tables 5 had been revised to clarify that tonnage grandfathering provisions of the International Convention on Tonnage Measurement of Ships, 1969 apply only to requirements of conventions that were in effect on July 18, 1982. h.

Definitions for the following terms and acronyms have been added: "international voyage"; "self-propelled vessel"; "non-self-propelled vessel"; "non-recreational vessel"; "GRT"; and "GT ITC."

Ch-3 to 11-93, Applicability of Tonnage Measurement Systems to U.S. Flag Vessels — APPLICABILITY. This NVIC applies to all U.S. flag vessels for which the application of a law

of the United States depends on the vessel's tonnage.

Ch-3 to 11-93, Applicability of Tonnage Measurement Systems to U.S. Flag Vessels — IMPLEMENTATION. Enclosure (1) provides requirements for tonnage measurement system

applicability to U.S. flag vessels. These requirements are derived from Title 46, United States Code, Subtitle II, Part J and Title 46, Code of Federal Regulations, Part 69. Officers in Charge, Marine Inspection, are encouraged to bring this Circular to the attention of appropriate individuals in the marine industry within their zones. This Circular will be distributed by electronic means only. It is available on the World Wide Web at http://www.uscg.mil/hq/g-m/nvic/index.htm. Encl: (1) Enclosure (1) to NVIC 11-93, CH-3

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. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.