Outer Continental Shelf National Center of Expertise (OCSNCOE)
Policy and Guidance - Mobile Offshore Drilling Unit (MODU)
The following content is available on this page (content is organized under the respective tabs):
1) USCG Marine Safety Manual (MSM), Vol II;
2) Overview of U.S. and Foreign-Flagged inspection/examination requirements;
3) Code of Federal Regulations (CFRs);
4) National Policy;
5) District Eight (Gulf of Mexico) Policy;
6) Navigation and Vessel Inspection Circulars (NVICs); and
7) MODU Applicability Flowchart.
Marine Safety manual
The following chapters of the Marine Safety Manual, Volume II: Section G - OCS Activities are applicable to MODUs:
○ Chapter 1, Regulations, Policy and Guidance for a Unit Conducting an OCS Activity,
○ Chapter 2, Procedures Applicable to U.S. MODUs, and
○ Chapter 3, Procedures Applicable to Foreign MODUs.
Overview of U.S. and Foreign Flagged inspection/examination requirements
U.S. Flagged MODUs are inspected to applicable portions of 33 CFR Subchapter N (Outer Continental Shelf Activities) and 46 CFR Subchapters I-A (Mobile Offshore Drilling Units), F (Marine Engineering), J (Electrical Engineering) & S (Subdivision and Stability). Note that additional portions of 33 CFR relating to Navigation and Pollution and 46 CFR relating to licensing/manning, lifesaving/firefighting type approvals and dangerous cargoes also apply.
Foreign-Flagged MODUs engaged in OCS activities must comply with one-of-three 'options' for "Design and Equipment" (see 33 CFR 143.207(a), (b) and (c)) AND one-of-three 'options' for "Operations" (see 33 CFR 146.205(a), (b) and (c)). Additional details related to these examination options and applicable regulatory cites are available by clicking on the following links (opens a pdf in a separate window):
○ Option A MODUs - examined to specific parts of the U.S. MODU regulations
○ Option B MODUs - PANAMA (Flag State equivalency)
○ Option B MODUs - MARSHALL ISLANDS (Flag State equivalency)
○ Option C MODUs - examined to the MODU Code, 1979
○ Option C MODUs - examined to the 1989 & 2009 MODU Codes (note that 33 CFR 143.207(c) and §146.205(c) both reference the Code for Construction and Equipment of Mobile Offshore Drilling Units (1979 MODU Code), but the 1989 and 2009 MODU Codes have been accepted as equivalencies under this examination option)
Code of Federal Regulations (CFRs)
CFRs that pertain to MODUs are as follows:
Primary subchapters -
○ 33 CFR Subchapter N - Outer Continental Shelf Activities
○ 46 CFR Subchapter I-A - Mobile Offshore Drilling Units
Additional subchapters that apply (not all will apply to each of the MODUs inspected or examined under the subchapters listed above) -
○ 46 CFR Subchapter A - Procedures Applicable to the Public
○ 46 CFR Subchapter B - Merchant Marine Officers and Seamen
○ 46 CFR Subchapter E - Load Lines
○ 46 CFR Subchapter F - Marine Engineering
○ 46 CFR Subchapter G - Documentation and Measurement of Vessels
○ 46 CFR Subchapter J - Electrical Engineering
○ 46 CFR Subchapter Q - Equipment, Construction and Materials: Specifications and Approval
○ 46 CFR Subchapter S - Subdivision and Stability
Note that 46 CFR Subchapters N, O, or V, or portions thereof, may also be utilized for vessels with specific arrangements/equipment or involved in specific operations.
○ 33 CFR Subchapter D - International Navigation Rules
○ 33 CFR Subchapter E - Inland Navigation Rules
○ 33 CFR Subchapter F - Vessel Operating Regulations
○ 33 CFR Subchapter H - Maritime Security (Parts 101, 103 and 104)
○ 33 CFR Subchapter O - Pollution
○ 33 CFR Subchapter P - Ports and Waterways Safety
Also note that 33 CFR Subchapter A also has applicability in regards to administration and legal actions.
CFRs can be viewed at ecfr.gov (regularly updated online version) or govinfo.gov (annual editions).
National policy letters that apply to MODUs are listed in the table below, grouped by issuing authority and ordered from newest to oldest (by policy number/original issue date). Click on the policy number to open the document (opens in a new window).
District Eight (Gulf of Mexico) Policy
D8 policy letters that apply to MODUs are listed in the table below, grouped by issuing authority and ordered from newest to oldest (by policy number/original issue date). Click on the policy number to open the document (opens in a new window).
Note that policy letter numbers for all policies listed from 1999 and earlier do NOT have a policy number referenced on the letter itself, but the policy number listed was assigned by D8 for tracking purposes.
Navigation and Vessel Inspection Circulars (NVICs)
NVICs that apply to MODUs are listed in the table below, ordered from newest to oldest (by NVIC number). Click on the NVIC number to open the document (opens in a new window). ALL NVICs can be found on the Official NVIC Page.
MODU Applicability Flowchart
For a pdf of the applicability flowchart displayed below, click here.