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.