46 CFR 11.493: Master-OSV endorsement service requirements

Last reviewed: October 14, 2026

This section sets the minimum service needed for a Master-OSV endorsement, with different rules for vessels under 1,600 GRT/3,000 GT and for 1,600 GRT/3,000 GT or more. It also explains tonnage limitations when an applicant lacks service on larger vessels. It covers STCW endorsements and possible Coast Guard exemptions.

Applies toApplicants for an endorsement as Master-OSV, and holders of that endorsement seeking an STCW endorsement.

What it says

  1. To qualify for Master-OSV of less than 1,600 GRT/3,000 GT, an applicant needs 24 months of total service as Mate, Chief Mate, or Master on self-propelled vessels of more than 100 GRT.

    46 CFR 11.493(a)“is 24 months of total service as Mate, Chief Mate, or Master of ocean or near-coastal and/or Great Lakes on self-propelled vessels of more than 100 GRT.”

  2. For the endorsement of less than 1,600 GRT/3,000 GT, service on inland waters may substitute for up to 50 percent of the required service.

    46 CFR 11.493(a)“Service on inland waters may substitute for up to 50 percent of the required service.”

  3. For Master-OSV of 1,600 GRT/3,000 GT or more, at least one-half of the required experience must be served as Chief Mate and be obtained on vessels of 1,600 GRT/3,000 GT or more.

    46 CFR 11.493(b)“At least one-half of the required experience must be served as Chief Mate and be obtained on vessels of 1,600 GRT/3,000 GT or more.”

  4. An applicant for Master-OSV of more than 1,600 GRT/3,000 GT who lacks the required service on vessels of 1,600 GRT/3,000 GT or more will receive a tonnage limitation based on qualifying experience.

    46 CFR 11.493(c)“a tonnage limitation will be placed on the officer endorsement based on the applicant's qualifying experience.”

  5. In no case will the limitation exceed 10,000 GRT/GT for OSVs unless the applicant meets the full requirements for an unlimited tonnage endorsement.

    46 CFR 11.493(c)“In no case will the limitation exceed 10,000 GRT/GT for OSVs unless the applicant meets the full requirements for an unlimited tonnage endorsement.”

  6. A Master-OSV endorsement holder may qualify for an STCW endorsement according to §§ 11.305 and 11.311.

    46 CFR 11.493(d)“A person holding an endorsement as Master-OSV may qualify for an STCW endorsement, according to §§ 11.305 and 11.311.”

  7. The Coast Guard may exempt an applicant from any STCW Regulation II/2 requirement it determines inappropriate or unnecessary for OSV service, or that the applicant meets under Article IX of STCW equivalency provisions.

    46 CFR 11.493(e)“The Coast Guard may exempt an applicant from meeting any requirement under STCW Regulation II/2”

Common questions

How much service do I need for a Master-OSV endorsement?

Both the under-1,600 GRT/3,000 GT and the 1,600 GRT/3,000 GT or more endorsements require 24 months of total service as Mate, Chief Mate, or Master on self-propelled vessels of more than 100 GRT.

“is 24 months of total service as Mate, Chief Mate, or Master of ocean or near-coastal and/or Great Lakes on self-propelled vessels of more than 100 GRT.”

Can inland service count toward Master-OSV?

For the endorsement of less than 1,600 GRT/3,000 GT, inland service may substitute for up to 50 percent of the required service.

“Service on inland waters may substitute for up to 50 percent of the required service.”

What is the minimum tonnage limitation on a Master-OSV endorsement?

The minimum tonnage limitation calculated under paragraph (c) is 2,000 GRT.

“However, the minimum tonnage limitation calculated according to this paragraph will be 2,000 GRT.”

Can a Master-OSV get an STCW endorsement?

A Master-OSV endorsement holder may qualify for an STCW endorsement according to §§ 11.305 and 11.311.

“A person holding an endorsement as Master-OSV may qualify for an STCW endorsement, according to §§ 11.305 and 11.311.”

The text of 46 CFR 11.493

Electronic Code of Federal Regulations (eCFR), current as of October 1, 2026 · Read it on eCFR

Master-OSV

Link to an amendment published at 91 FR 60883, Sept. 25, 2026.

(a) The minimum service required to qualify an applicant for an endorsement as Master-OSV of less than 1,600 GRT/3,000 GT is 24 months of total service as Mate, Chief Mate, or Master of ocean or near-coastal and/or Great Lakes on self-propelled vessels of more than 100 GRT. Service on inland waters may substitute for up to 50 percent of the required service. At least one-half of the required experience must be served as Chief Mate.

(b) The minimum service required to qualify an applicant for Master-OSV of 1,600 GRT/3,000 GT or more is 24 months of total service as Mate, Chief Mate, or Master of ocean or near-coastal and/or Great Lakes on self-propelled vessels of more than 100 GRT. At least one-half of the required experience must be served as Chief Mate and be obtained on vessels of 1,600 GRT/3,000 GT or more.

(c) If an applicant for Master-OSV of more than 1,600 GRT/3,000 GT does not have the service on vessels of 1,600 GRT/3,000 GT or more as required by paragraph (b) of this section, a tonnage limitation will be placed on the officer endorsement based on the applicant's qualifying experience. The endorsement will be limited to the maximum tonnage on which at least 25 percent of the required experience was obtained, or 150 percent of the maximum tonnage on which at least 50 percent of the service was obtained, whichever is higher. However, the minimum tonnage limitation calculated according to this paragraph will be 2,000 GRT. Limitations are in multiples of 1,000 GRT using the next higher figure when an intermediate tonnage is calculated. In no case will the limitation exceed 10,000 GRT/GT for OSVs unless the applicant meets the full requirements for an unlimited tonnage endorsement.

(d) A person holding an endorsement as Master-OSV may qualify for an STCW endorsement, according to §§ 11.305 and 11.311.

(e) The Coast Guard may exempt an applicant from meeting any requirement under STCW Regulation II/2 (incorporated by reference, see § 11.102 of this part) that the Coast Guard determines to be inappropriate or unnecessary for service on an OSV, or that the applicant meets under the equivalency provisions of Article IX of STCW.

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 October 1, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.