Diesel Boats and Ships

Marine diesel engines used on a variety of different types of vessels ranging in size and application from small recreational runabouts to large ocean-going vessels are significant contributors to air pollution in many of our nation’s cities and coastal areas. New marine diesel engines must meet increasingly stringent emissions requirements, yet these engines continue to emit significant amounts of nitrogen oxides (NOx) and particulate matter (PM), both of which contribute to serious public health problems.

EPA is addressing emissions from marine engines in two ways, through their fuels and through their emission limits.

In May 2004, as part of the Clean Air Nonroad Diesel Rule, EPA finalized new requirements for nonroad diesel fuel that decrease the allowable levels of sulfur in fuel used in marine vessels by 99 percent. These fuel improvements, which began to take effect in 2007, are creating significant environmental and public health benefits by reducing PM from new and existing engines.

In March 2008, EPA finalized a three part program that will dramatically reduce emissions from marine diesel engines below 30 liters per cylinder displacement. These include marine propulsion engines used on vessels from recreational and small fishing boats to towboats, tugboats and Great Lake freighters, and marine auxiliary engines ranging from small generator sets to large generator sets on ocean-going vessels. The rule will cut PM emissions from these engines by as much as 90 percent and NOx emissions by as much as 80 percent when fully implemented.

The 2008 final rule includes the first-ever national emission standards for existing marine diesel engines, applying to engines larger than 600kW when they are remanufactured. The rule also sets Tier 3 emissions standards for newly-built engines that are phasing in from 2009. Finally, the rule establishes Tier 4 standards for newly-built commercial marine diesel engines above 600kW, based on the application of high-efficiency catalytic after-treatment technology, phasing in beginning in 2014.

The Ocean Vessels and Large Ships page includes information on U.S. regulations for Category 3 marine diesel engines as well as the international treaty called MARPOL Annex VI with standards that apply for marine diesel engines over 130 kW. Information is also available on Gasoline Boats and Personal Watercrafts.

Regulations

See the electronic Code of Federal Regulations (e-CFR) for the full text of current regulations that apply to marine diesel engines:

Marine diesel engines under 37 kW - 40 CFR part 89 or part 1042
Marine diesel engines 37 kW and above - 40 CFR part 94 or part 1042
Marine diesel engines over 130 kW – 40 CFR part 1043 - Regulations implementing MARPOL Annex VI

NOTE: You will need Adobe Acrobat Reader, available as a free download, to view some of the files on this page. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader.

Final Rule: Category 3 Marine Diesel Engines (signed December 18, 2009)
- See the Final Rule on our Ocean Vessels and Large Ships page.
Final Rule: Control of Emissions of Air Pollution from Locomotives and Marine Compression-Ignition Engines Less Than 30 Liters per Cylinder (published May 6, 2008)
- Fact Sheet: EPA Finalizes More Stringent Emissions Standards for Locomotive Engines and Marine Compression-Ignition Engines (PDF) (5 pp, 134K, March 2008, EPA420-F-08-004)
- Final Rule
  - Preamble and 40 CFR Parts 85-94 (Pages 25097-25146) | PDF Version (50 pp, 364K)
  - Pages 25147-25196 | PDF Version (50 pp, 1,141K)
  - Pages 25197-25246 | PDF Version (50 pp, 922K)
  - Pages 25247-25296 | PDF Version (50 pp, 1347K)
  - Pages 25297-25346 | PDF Version (50 pp, 1316K)
  - Pages 25347-25352 | PDF Version (6 pp, 158K)
- Regulatory Impact Analysis (PDF) (739 pp, 10MB, May 2008, EPA420-R-08-001a)
- Summary and Analysis of Comments (PDF) (463 pp, 2.4MB, March 2008, EPA420-F-08-006) Instead of downloading the entire document, you can access the individual chapters of the Summary and Analysis of Comments.
- See the Proposed Rule (published April 3, 2007) and the Advance Notice of Proposed Rulemaking (published June 29, 2004) for the rules, fact sheets, and technical support documents.
Final 2005 Technical Amendments – Procedures for Testing Highway and Nonroad Engines and Omnibus Technical Amendments (published July 13, 2005)
- Fact Sheet: Regulatory Announcement: Changed Test Procedures for Nonroad Engines and Heavy-Duty Highway Engines (PDF) (4 pp, 134K, EPA420-F-05-036, July 2005)
- Federal Register Notice:
  Part 1, pp 40419-40468 | PDF Version (949K)
  Part 2, pp 40469-40518 | PDF Version (938K)
  Part 3, pp 40519-40568 | PDF Version (6.71MB)
  Part 4, pp 40569-40612 | PDF Version (1.8MB)
- Technical Support Document and Summary & Analysis of Comments (PDF) (115 pp, 1.7MB, EPA420-R-05-008, June 2005)
- See Proposed Technical Amendments for the proposed rule, fact sheet, and technical support documents (published September 10, 2004).
Final Rule for Recreational Marine Diesel Engines (published November 8, 2002)
- Fact Sheet: Emission Standards for New Nonroad Engines — Large Industrial Spark-ignition Engines, Recreational Marine Diesel Engines, and Recreational Vehicles (PDF) (7 pp, 412K, EPA420-F-02-037, September 2002)
- Federal Register Notice | PDF Version (207 pp, 1.1MB, published November 8, 2002)
- Summary and Analysis of Comments (PDF) (319 pp, 1.07MB, EPA420-R-02-023, September 2002)
- Final Regulatory Support Document (PDF) (687 pp, 2.6MB, EPA420-R-02-022, September 2002)
  - Final Regulatory Support Document by Chapter
- Environmental Impacts of Newly Regulated Nonroad Engines (PDF) (5 pp, 24K, EPA420-F-02-033, September 2002)
- Frequently Asked Questions from Owners of Recreational Boats with Diesel Engines (PDF) (3 pp, 399K, EPA420-F-02-042, September 2002)
- Emission Factors for Recreational Marine Diesel Engines (PDF) (4 pp, 60K, EPA420-F-02-044, September 2002)
- How to Maintain or Rebuild Engines Certified to EPA Standards (PDF) (6 pp, 407K, EPA420-F-02-035, September 2002)
- Blue Sky Series Engines (PDF) (3 pp, 397K, EPA420-F-02-036, September 2002)
- Plain-Language Format of Emission Regulations for Nonroad Engines (PDF) (6 pp, 405K, EPA420-F-02-046, September 2002)
- Docket index (as of Sept. 13, 2002 (PDF)) (141 pp, 690K)
- Other related documents regarding the final rule are available at www.epa.gov/otaq/regs/nonroad/2002/cleanrec-final.htm
- See Proposed Emission Standards for the proposed rule, fact sheet and regulatory support documents.
Final Rule - Emission Standards for Commercial Marine Diesel Engines (published December 29, 1999)
- Fact Sheet: Emission Standards for New Marine Commercial Engines (PDF) (2 pp, 9K, EPA420-F-99-043, November 1999)
- Federal Register Notice | PDF Version (75 pp, 512K, published December 29, 1999)
- Summary and Analysis of Comments: Control of Emissions from Marine Diesel Engines (PDF) (94 pp, 410K, EPA420-R-99-028, November 1999)
- Final Regulatory Impact Analysis: Control of Emissions from Marine Diesel Engines (PDF) (132 pp, 966K, EPA420-R-99-026, November 1999)
- 5Docket Index (PDF) (29 pp, 52K)
- In-Use Marine Diesel Fuel (PDF) (21 pp, 68K, EPA420-R-99-027, August 1999)
- Commercial Marine Emissions Inventory for EPA Category 2 and 3 Compression Ignition Marine Engines in the United States and Continental and Inland Waterways (PDF) (58 pp, 248K, EPA420-R-98-020, August 1998)
- Incremental Cost Estimates for Marine Diesel Engine Technology Improvements (PDF) (48 pp, 182K)
- Additional Fact Sheets
  - Emission Standards for Marine Diesel Engines: Scope of Application (PDF) (4 pp, 16K, EPA420-F-00-006, February 2000)
  - Responsibilities for Marine Vessel Operators with EPA-Certified Engines (PDF) (3 pp, 11K, EPA420-F-99-044, December 1999)
  - How to Maintain or Rebuild Engines Certified to EPA Standards (PDF) (6 pp, 407K, EPA420-F-02-035) (supersedes "Rebuilding Engines" EPA420-F-99-045, December 1999)
- Blue Sky Series Engines (PDF) (3 pp, 397K, EPA420-F-02-036) (supersedes "Blue Sky Series Engines" EPA420-F-99-048, December 1999)
- Guidance Documents
- Engine Dressing Letter, September 8, 2003 (PDF) (3 pp, 178K)
- See Proposed Rule for Emission Standards for Commercial Marine Diesel Engines for the proposed rule, fact sheet and regulatory support documents.

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Guidance and Publications

Marine Remanufacture Program
EPA has developed Frequently Asked Questions from Marine Engine Owners and Rebuilders about EPA's Marine Remanufacture Program (PDF) (7 pp, 160K, EPA420-F-09-003, January 2009) that explains its 2008 regulations relating to remanufacturing of in-use marine diesel engines, and how interested parties can find out more about certifying and obtaining remanufacture systems.
Portable Auxiliary Marine Engines - Interpretation of Installed (PDF) (2 pp, 54K, CISD-06-012, May 5, 2006)
Overview of EPA's Emission Standards for Marine Engines (PDF) (9 pp, 184K, EPA420-F-04-031, August 2004)
Commercial Marine Emission Inventory Development Final Report (PDF) (163 pp, 2M, EPA420-R-02-019, July 2002)
Modeling Commercial Marine Emission Inventories
EPA's marine inventory guidance document (EPA420-R-92-009, December 1992) uses modeling techniques based on fuel consumption that were common at that time. Since then, we have developed new marine inventory techniques as part of our rulemaking process for emission standards for commercial marine diesel engines. Chapter 7 of the Final Regulatory Support Document (PDF) (153 pp, 647K, EPA420-R-03-004, January 2003) contains our inventory estimates for Category 3 commercial marine vessels. Chapter 5 of the Final Regulatory Impact Analysis (PDF) (132 pp, 966K, EPA420-R-99-026, November 1999) contains our inventory estimates and a description of how those estimates were produced for Category 1 and 2 commercial marine vessels.
Analysis of Commercial Marine Vessels Emissions and Fuel Consumption Data (PDF) (158 pp, 2.6MB, EPA420-R-00-002, February 2000)
Commercial Marine Activity in the United States Final Reports
- Commercial Marine Activity for Great Lake and Inland River Ports in the United States (PDF) (84 pp, 360K, EPA420-R-99-019, September 1999)
- Commercial Marine Activity for Deep Sea Ports in the United States (PDF) (214 pp, 1MB, EPA420-R-99-020, September 1999)
- Both Reports in WordPerfect format and Tables as Excel 5 spreadsheets 590K ZIP
Nonroad Engine and Vehicle Emission Study Report (PDF) (141 pp, 1.8MB), Appendices (PDF) (415 pp, 7.7MB) (Publication nos. EPA-21A-2001 or EPA460/3-91-002, November 1991)

Paper copies of this study are available from the National Technical Information Service (NTIS) - Publication #PB-92-126960

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