OCSNCOE Unit Emblem (silhouettes of a self-elevating MODU, an OSV and an offshore wind turbine over a silhouette of the United States with the U.S. Coast Guard mark (i.e., racing stripe) in the background).Outer Continental Shelf National Center of Expertise (OCSNCOE)

JACK ST. MALO during offshore construction with attending OSV and Floatel VICTORY. C-ENFORCER underway with water cannons flowing. SEVAN LOUISIANA underway when initially entering the U.S. Gulf of Mexico. Platform GINA off the California coast. Block Island windfarm with attending CTV. SPARTAN 151 dockside in Seward, AK.



Additional OCS & Coast Guard-Related Info Menu


The Drill Down, Issue #12: Existing Offshore Supply Vessels - Public Law 96-378

Graphic of a drill stringIntroduction

The first Offshore Supply Vessel (OSV) Drill Down, explored the advent and evolution of OSVs throughout the years. This issue explores Public Law 96-378, the first regulations to define “Offshore Supply Vessel” and “OSV Service.” It established the first regulatory path for vessels to enter service on the Outer Continental Shelf. 

Public Law 96-378

The invention of offshore drilling led to an increased number of vessels transporting goods and personnel on the OCS. Public Law 96-378 (P.L. 96-378, signed October 6, 1980), also known as the Small Vessels, Inspection and Manning Act, was the first step towards creating consistent safety regulations for these vessels. P.L. 96-378 created the “Offshore Supply Vessel” type and service by defining an OSV as a vessel that:
   1. is propelled by machinery other than steam,
   2. is not within the description of passenger carrying vessels in Section 1 of the Act of May 10, 1956 (70 Stat. 151) as amended (46 USC 390),
   3. is of more than 15 and less than 500 gross tons, and
   4. regularly carries goods, supplies, or equipment in support of exploration, exploitation, or production of offshore mineral and energy re-sources.

Entering Offshore Supply Vessel Service

P.L. 96-378 required inspection of all vessels engaged in OSV service. Provisions were made to allow vessels to enter certificated service as an:
   1. “Existing OSV”-Certificated Prior to P.L. 96-378,
   2. “Existing OSV”-Non-Certificated Prior to P.L. 96-378, or
   3. “New Vessel”

An Existing OSV was defined as:
   1. a vessel operating as such on or before January 1, 1979, or
   2. a vessel, if not in service of any kind, on or before that date (1Jan79) and was contracted for and entered service as such before October 6, 1980

Certificated prior to P.L. 96-378  (Figure 1-Gray)

Vessels already certificated as either Subchapter I or T prior to P.L. 96-378 had to make a choice, either:
   1. modify operations to comply with the vessel’s specific service -

  • 46 CFR Subchapter I (Cargo & Misc. Vessel), or
  • 46 CFR Subchapter T (Small Passenger Vessel)
  • and no longer conduct any service now regarded as OSV service;


   2. continue service as an OSV while maintaining their previous certification -

  • 46 CFR Subchapter I, or
  • 46 CFR Subchapter T.

Vessels continuing service as an OSV were restricted in the types of cargo and persons carried (e.g. persons in addition to the crew). These vessels choosing OSV service, were no longer authorized to carry passengers.Photo of the Chevy Elevator

Vessels in this group would not be required to meet forthcoming OSV regulations, but instead would maintain compliance with the existing regulations. However, if the vessel or its equipment was modified, compliance with the current applicable regulations would be required.

Image right: Chevy Elevator, Built in 1965, Certificated OSV Under Subchapter T.  (Source: Cajun Stabilizing Boats, Inc.).

Not Certificated prior to P.L. 96-378 (Figure 1-Orange)

Vessels operating in support of the offshore energy industry that were not certificated, were now required to be inspected and certificated under two options:
   1. If less than 100 gross tons, 46 CFR Subchapter T (Small Passenger Vessel).
   2. If over 100 gross tons, 46 CFR Subchapter I (Cargo & Misc. Vessel).

Registration with the USCG was required within 3 months and an initial inspection was to occur within 2 years of registration or no later than January 6, 1983. Existing OSVs that failed to comply, lost eligibility to work in support of the offshore energy industry (OSV service). P.L. 96-378 provided exemptions from major structural or equipment standards for existing OSVs. For example, instead of requiring replacement, if non-USCG approved firefighting or lifesaving equipment was found on board, the local USCG inspection office could determine if adequate protection was provided. 

NVIC 8-81, Change 1 & NVIC 8-91

After P.L. 96-378, USCG published policy and procedures on the inspection of “existing” OSVs in Navigation and Vessel Inspection Circulars (NVICs).  These NVICs detailed the registration deadlines and relaxed structural and equipment requirements previously discussed. The relevant NVICs to “existing OSVs” are:

  • NVIC 8-81: Initial & Subsequent Inspection of Uncertificated Existing Offshore Supply Vessels under P.L. 96-378 (published July 27, 1981),
  • NVIC 8-81, Change 1: Change 1 to NVIC 8-81 added: Encl (3) Inspection of Existing Liftboats (published March 23, 1988), and
  • NVIC 8-91: Initial & Subsequent Inspection of Existing, Uncertificated Offshore Supply Vessels, including Liftboats (published May 21, 1991).

Change 1 to NVIC 8-81 added the inspection requirements for existing liftboats, specifically addressing standards for stability and lifting gear. The publication of NVIC 8-91 then canceled NVICs 8-81 and 8-81, Change 1, but it retained most of the contents of the superseded NVICs. The superseded NVICs do provide definitions and historical context not found in NVIC 8-91, therefore they are relevant to the overall definition and discussion of “existing OSVs.”

New Offshore Supply Vessel (Figure 1-Yellow)

A “New OSV” was any vessel which did not meet the definition of an “existing OSV”. These vessels were required to enter service certificated under Subchapter I or T as applicable, with no exemptions allowed by the NVICs. 

Photo of the M/V Dip

Image above:  M/V Dip, Built in 1980, Certificated OSV under Subchapter I (Source: Gulf Offshore Logistics, LLC.)

20 Years of ServicePhoto of the Captain Ron

P.L. 96-378 also required the update of “existing OSVs” after 20 years of service. After January 1989, a vessel over 20 years old was required to continue service as a “new OSV”. These vessels continued to operate but were brought into compliance with Subchapter I or T, as applicable by their build date, with no exemptions allowed by the NVICs. Therefore, the term “existing OSV”, as defined by P.L. 96-378, is obsolete as of January 1998.        

Image left: M/V CAPTAIN RON, Built in 1980, Certificated OSV Under Subchapter T. (Source: Gulf Offshore Logistics, LLC.).


A summary of the regulatory path and significant dates for “existing OSVs” is provided in Figure 1 and Figure 2 (below). Although the term “existing vessels” as defined by P.L. 96-378 is obsolete, an understanding of the original OSV regulations provides historical reference for the regulations enforced today. Several of these vessels, including those pictured in this issue, are still operating and are inspected under the context of these older regulations.  46 Code of Federal Regulations, Subchapter L would later redefine the term “existing OSVs” and promulgate more specific regulations. A future Drill Down issue will discuss the development and publication of Subchapter L: Offshore Supply vessel, enacted in 1996.

Graphic depicting Existing OSV Regulatory Path

Figure 1: P.L. 96-378 “Existing Offshore Supply Vessel” Regulatory Path

Timeline for Existing OSV Regulations and Policy

Figure 2: “Existing Offshore Supply Vessel” Regulatory and Policy Timeline