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


Offshore Renewable Energy (Non-Mineral) Support Vessel Frequently Asked Questions (FAQs)

Please find answers to commonly asked questions related to vessels supporting non-mineral activities on the U.S. Outer Continental Shelf below.

Answers in this FAQ section are not a substitute for applicable legal requirements, nor are they rules (however, some questions may have an answer that comes directly from existing regulation or policy). The answers are not intended to require or impose legally binding requirements on any party. Answers provided represent the OCSNCOE’s current thinking, after researching existing regulations and policy, as well as consultation with Coast Guard Subject Matter Experts. These answers are intended to assist industry, mariners, the public, the Coast Guard and other regulators in applying statutory and regulatory requirements. When available, the FAQ will direct the reader to the official documents, such as the Federal Register, the Code of Federal Regulations or NVICs and policies. The answers provided are subject to change with regulatory or policy updates.

Regulatory Requirements
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 1) Are foreign-flagged wind farm vessels subject to USCG Port State Control (PSC) exams?

Yes, if entering port or U.S. territorial seas.

PSC exams are required only for vessels that “arrive” in the U.S. by coming into port or anchoring within 12 nautical miles (NM). Some wind farm installation vessels bound for the U.S. Outer Continental Shelf may never arrive in the U.S. and may remain beyond 12 NM while conducting operations. If these vessels do not arrive in the U.S., they are NOT required to undergo a PSC exam by the local OCMI.

Vessels that do not arrive and are not required by their operations to enter inside 12 NM may not have a need for an exam for the duration of their activities.

Published 01Nov2023.

 2) What international certificates are accepted for Port State Control (PSC) compliance of a foreign-flagged windfarm vessel entering U.S. port?

As a core, the valid applicable safety certificates required by the SOLAS convention and the applicable environmental compliance certificates required by MARPOL remain acceptable for general PSC compliance.

Alternatively, some flag states and class societies are issuing Mobile Offshore Unit (MOU) safety certificates based on the vessel meeting the design and operating criteria of the MODU Code, in lieu of (or in conjunction with) the applicable SOLAS safety certificates. There are a couple of important items to note in these cases:

1) Due to the unique designs and operations of many foreign wind farm vessels, the MODU code offers a logical and acceptable alternative level of safety, and so has been accepted for PSC compliance.

2) Some vessels are issued MOU certificates based on the national standards of the vessel’s flag state. National MOU certificates are not acceptable for PSC compliance. The vessel must have valid safety certificates associated with international convention or code (SOLAS or MODU Code).

Additionally, foreign vessels arriving with more than 12 persons in addition to crew (such as wind farm installation techs and the like) should be currently certificated to comply with international convention by certification as either a passenger ship or alternatively a Special Purpose vessel under the Special Purpose Ships (SPS) Code. For awareness purposes, the Industrial Persons (IP) Code has been accepted by IMO and is set to go into effect in July of 2024 as a new Chapter of SOLAS and will offer an alternative for large industrial vessels on international voyages carrying more than 12 industrial persons (per IMO definition). Note that this does not impact vessels approved under the MODU Code (since it already provides for the carriage of more than 12 persons in addition to crew on international voyages), as long as the vessel meets the lifesaving equipment carriage and operational requirements, versus simply the vessel design standards.

Developed in conjunction with CG-CVC guidance. Published 01Nov2023.

Dynamic Positioning (DP) Systems
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 1) Does the U.S. Coast Guard consider a vessel equipped with a dynamic positioning (DP) system to be self-propelled?

Short Answer:

Yes, in most circumstances.


While USCG regulations do not explicitly mention DP systems, the topic has been discussed in numerous CG policies, guidance and legal reviews.

Note: Additional case-by-case reviews and determinations may have been made by the CG in regard to DP as propulsion, but only those that have been available to the public are discussed in this explanation.

NVC 8-68 first addressed this issue when released on November 15, 1968, due to "an increasing number of non-self-propelled units being equipped with positioning machinery, steering aids and propulsion assist units." In this NVC, the CG policy on tunnel type "thrusters" and "kickers" used solely for transiting locks and/or canals would not be considered as a basis for classifying a vessel as self-propelled. However, the NVC went on to say that "vessels equipped with directional maneuvering equipment and/or substantial propulsion assist units will normally be considered as self-propelled vessels" regardless of if a towing vessel was employed in the operation.

NVC 8-68 was cancelled by Change 1 to Marine Safety Manual Volume II (MSM II) on July 7, 2014, and the language of the policy was condensed and included at MSM II A.6.F (pages A6-6 and A6-7). The policy was modified for vessels equipped with directional moving equipment to note that "this would include dynamic positioning (DP)". MSM II A was moved to COMDTINST 16000.70 on Sep 20, 2021, but the policy remained the same:

"To further clarify, unidirectional tunnel type "thrusters" and "kickers" used solely for transiting locks and/or canals would NOT be considered a basis for classifying a vessel as self-propelled. Vessels equipped with directional maneuvering equipment and/or substantial propulsion assist units will normally be considered self-propelled (this would include dynamic positioning (DP)); notwithstanding the fact that a towing vessel may be employed in the operation."

CG-094 (Judge Advocate General and Chief Counsel) issued a memorandum to CG-5 (Assistant Commandant for Marine Safety, Security and Stewardship) on February 11, 2011, with the subject of "Potential Legal Issues Associated with Vessels Employing Dynamic Positioning Systems" and the redacted memo was included as Appendix I to the Report of Investigation for the MODU DEEPWATER HORIZON casualty. The memo thoroughly discusses the law and history surrounding vessels and the classification of being self-propelled. At paragraph 23, the memo concludes that:

"Under current law, a watercraft operating with a DP System is an underway, self-propelled vessel, and subject to all the regulatory requirements of "traditional" vessels."

The USCG Marine Safety Center (MSC) states that "DP systems are propulsion control systems and are considered as vital systems" in section 4 of MSC Plan Review Guidance Procedure No. E2-24, dated December 14, 2021. The previous revision of the procedure, dated November 9, 2011, essentially stated the same thing, although in less direct verbiage. MSC Technical Note 02-11, CH-1, dated December 11, 2020, states in paragraph 2.b that "DP systems are considered to be a vital component of the propulsion control system" and goes on to say that "DP systems are routinely used as the primary maneuvering system during critical operations".

Frequently asked questions are posted on both the NAVCEN and OCSNCOE websites that state that a vessel that is using DP to maintain position is considered as underway, not making way in regard to the Navigation Rules and should be marked by navigation lighting or dayshapes to indicate that condition.

While a DP system may have the primary purpose of station keeping or proceeding along a specific path (usually for an industrial purpose, such as pipe laying or cable laying), the CG has considered systems that have the ability to move and maneuver a vessel as a means of self-propulsion for more than 50 years and has reiterated that DP systems fall within that category.

Published 09Jan2024.