NVIC 05-93: Certification of passenger carrying submersibles
Last reviewed: October 14, 2026
NVIC 5-93 is Coast Guard guidance for certifying passenger carrying submersibles under Subchapter T. It says the inspection statutes and Subchapter T apply to any submersible less than 100 gross tons carrying more than six passengers. It also covers smaller and recreational submersibles.
What it says
The inspection statutes of U.S. Code Title 46 and the Subchapter T regulations apply to any submersible less than 100 gross tons carrying more than six passengers.
NVIC 05-93 b.“the inspection statutes of U.S. Code Title 46 - Shipping (46 U.S.C.) and the regulations in 46 CFR Subchapter T - Small Passenger Vessels (46 CFR Parts 175-187) apply to any submersible less than 100 gross tons carrying more than six passengers.”
Submersibles carrying six or fewer passengers are subject to regulation as uninspected vessels under 46 CFR Subchapter C - Uninspected Vessels (46 CFR Parts 24-26).
NVIC 05-93 c.“However, they are subject to regulation as uninspected vessels under 46 CFR Subchapter C - Uninspected Vessels (46 CFR Parts 24-26).”
Smaller submersibles may be subject to special local operating restrictions imposed by the Captain of the Port (COTP).
NVIC 05-93 c.“they may be subject to special local operating restrictions as may be imposed by the Captain of the Port (COTP)”
Recreational submersibles must comply with 33 CFR, Subchapter S (Boating Safety).
NVIC 05-93 d.“Recreational submersibles must comply with 33 CFR, Subchapter S (Boating Safety).”
When a submersible is in a collision, accident, or casualty, the operator must report it to the appropriate Officer in Charge, Marine Inspection (OCMI) or state authorities. The operator must also render all possible assistance to others involved.
NVIC 05-93 d.“the operator is required to report such occurrences to the appropriate Officer in Charge, Marine Inspection (OCMI) or state authorities, and to render all possible assistance to others involved in such incidents.”
Designers, builders and operators must also be familiar with and use the referenced materials.
NVIC 05-93 e.“Designers, builders and operators must also be familiar with and use the referenced materials.”
Coast Guard plan review, inspection, and certification will be based on the guidance in this circular.
“Coast Guard plan review, inspection, and certification will be based on the”
Common questions
Does Subchapter T apply to passenger submersibles?
Yes, it applies to any submersible less than 100 gross tons carrying more than six passengers.
“apply to any submersible less than 100 gross tons carrying more than six passengers.”
How are submersibles carrying six or fewer passengers regulated?
They are subject to regulation as uninspected vessels under 46 CFR Subchapter C - Uninspected Vessels (46 CFR Parts 24-26).
“they are subject to regulation as uninspected vessels under 46 CFR Subchapter C - Uninspected Vessels (46 CFR Parts 24-26).”
Do submersible, submarine and sub mean different things in this circular?
No. The circular says the three terms have no difference in meaning.
“submersible, submarine, and sub have no difference in meaning.”
What rules apply to recreational submersibles?
They must comply with 33 CFR, Subchapter S (Boating Safety).
“Recreational submersibles must comply with 33 CFR, Subchapter S (Boating Safety).”
The text of NVIC 05-93
U.S. Coast Guard, NVIC 05-93 (main body; enclosures not shown)
Guidance for Certification of Passenger Carrying Submersibles
COMDTPUB P16700.4 NVIC 5-93 JULY 20, 1993 NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 5-93 Electronic Version for Distribution Via the World Wide Web Subj: GUIDANCE FOR CERTIFICATION OF PASSENGER CARRYING SUBMERSIBLES
Guidance for Certification of Passenger Carrying Submersibles — PURPOSE. This circular provides guidance for certification of passenger carrying submersibles
under Title 46, Code of Federal Regulations, Subchapter T - Small Passenger Vessels (under 100 gross tons) (46 CFR Parts 175-187).
Guidance for Certification of Passenger Carrying Submersibles — DIRECTIVES AFFECTED. None.
DIRECTIVES AFFECTED. None.
Guidance for Certification of Passenger Carrying Submersibles — DISCUSSION.
a.
Nonmilitary submersibles have been used for several decades in the industrial, experimental and research fields.
The first successful commercial passenger carrying submersible was the AUGUSTE PICCARD (Switzerland, 1964-65).
The first passenger carrying submersible operation in waters subject to Coast Guard jurisdiction commenced in 1987 at St.
Thomas, U.S.
Virgin Islands. b.
For operations under U.S. jurisdiction, the inspection statutes of U.S.
Code Title 46 - Shipping (46 U.S.C.) and the regulations in 46 CFR Subchapter T - Small Passenger Vessels (46 CFR Parts 175-187) apply to any submersible less than 100 gross tons carrying more than six passengers.
Since the regulations were developed primarily with surface craft in mind, many of the requirements cannot be applied to or may otherwise be inappropriate for submersibles.
Additionally, there are many measures not in the regulations which must be applied to attain an equivalent level of safety to that of surface craft, and otherwise minimize any inherent hazards of underwater operation. c.
There has also been much interest regarding the operation of smaller submersibles carrying six or fewer passengers.
To date, only a few such operations exist.
Such vessels are not subject to present inspection laws.
However, they are subject to regulation as uninspected vessels under 46 CFR Subchapter C - Uninspected Vessels (46 CFR Parts 24-26).
Design, construction and operation must be accomplished in a safety-conscious manner due to the significantly greater inherent risk to passengers (compared to surface vessels) and the unique nature of the vessels.
Additionally, they may be subject to special local operating restrictions as may be imposed by the Captain of the Port (COTP) relative to navigation safety, port safety and security, and vessel traffic considerations.
Note; At the time of writing of this publication, Bill H.R. 1159 was before Congress to require certification of all submersibles carrying one or more passengers for hire.
NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 5-93 d.
Recreational submersibles must comply with 33 CFR, Subchapter S (Boating Safety).
Undocumented submersibles (i.e., those not having federal documentation) with propulsion equipment, must be numbered in accordance with the federal numbering system or the numbering system of the state in which the submersible will be principally operated, in addition, recreational vessels must carry a Hull Identification Number (HIN).
When a submersible is involved in a collision, accident, or casualty, the operator is required to report such occurrences to the appropriate Officer in Charge, Marine Inspection (OCMI) or state authorities, and to render all possible assistance to others involved in such incidents.
The regulations contained in 33 CFR 155 (Oil Pollution Prevention Regulations for Vessels) and 33 CFR 159 (Marine Sanitation Devices) also apply to recreational submersibles.
Voluntary reports of recreational submersible operations in or near U.S. waters may be made to the nearest Coast Guard Operations Center.
These reports are intended for informative use in search and rescue (SAR) activities only.
Inquiries about the extent of such reports and other questions that cannot be resolved locally should be directed to Commandant (G-NRS) at (commercial/FTS) 202/8-267-1948. e.
Enclosure (1) to this circular provides general guidance relative to the inspection and certification requirements for submersibles, primarily those carrying more than six passengers.
Enclosure (2) to this circular provides general guidance relative to the stability of the vessel, and enclosures (3) through (5) provide reference information.
This document does not stand alone, i.e., it makes reference to the applicable regulations and to the appropriate industry standards.
Designers, builders and operators must also be familiar with and use the referenced materials. f.
Submersible technology is not new, but its application in the passenger carrying industry is still very much under study.
Although we have established a safe baseline, as this industry grows we will see many technological advances which will have to be carefully considered in view of safety.
The Coast Guard has used the results of two recent studies on passenger submersible safety as well as in-house research in developing these guidelines.
Together with other recognized standards described or mentioned in enclosure (1), and until new regulations become necessary, this document is considered to be the best available guidance to facilitate this industry while ensuring passenger safety. g.
For the purposes of this document; submersible, submarine, and sub have no difference in meaning.
All three terms are used interchangeably to describe any self-propelled vessel carrying passengers and crew which is designed to operate on the surface, submerge, operate submerged, surface and remain afloat.
Internal pressure is normally maintained at or near one atmosphere.
NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 5-93
Guidance for Certification of Passenger Carrying Submersibles — IMPLEMENTATION. Coast Guard plan review, inspection, and certification will be based on the
guidance contained in this circular. Owners, operators, designers and builders of passenger carrying submersibles must become familiar with the applicable regulations and standards. To facilitate a timely inspection for certification, they are also urged to closely follow the guidelines of enclosures (1) through (6). End: (1) Guidance for Certification of Passenger Carrying Submersibles (2) Guidelines for Stability of Small Passenger Submersibles (3) References (4) Addresses (5) Urban Mass Transportation Administration (UMTA) Recommended Fire Safety Practices for Rail Transit Materials Selection (6) Failure Modes and Effects Analysis (FMEA) Non-Standard Distribution: C:e Honolulu, Puget Sound (35); Miami, Long Beach, Portland OR (25); Jacksonville (20); Anchorage (15); San Juan, Tampa, San Diego, Juneau, Valdez (10); San Francisco, Guam (5); New Orleans, Hampton Roads, Baltimore, Philadelphia, Port Arthur, Houston, Mobile, Morgan City, Boston, Portland ME, Charleston, Galveston, Louisville, Memphis, Paducah, Pittsburgh, St. Louis, Savannah, Cleveland, Buffalo, Chicago, Detroit, Duluth, Milwaukee, Providence, Huntington, Wilmington, Corpus Christi, Toledo (1). C:m New York(S); Sturgeon Bay (4); St. Ignace (1). D:d Except Baltimore and Moriches. D:l CG Liaison Officer MILSEALIFTCOMD (Code N-7CG), CG Liaison Officer RSPA (DHM-22), CG Liaison Officer MARAD (MAR-742), CG Liaison Officer JUSMAGPHIL, CG Liaison Officer World Maritime University, CG Liaison Officer ABS (1). ABS (24). Det Norske (1). NOAA Fleet Inspection Officer (1). U.S. Merchant Marine Academy (1).
Sections it refers to
- 33 CFR 155
- 33 CFR 159
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.