Recreational Marine Engines - Background

This page last reviewed May 13, 2010

image of speed boat

ARB's recreational marine engine program is an important new element in ARB's efforts to improve air quality through reductions of hydrocarbon (HC) and oxides of nitrogen (NOx) emissions. Regulations have been adopted for certain marine vessels and regulations have been proposed for other spark-ignition engines used in boats for propulsion. Commercial marine engines are covered under the Commercial Marine Vessel web page. Spark-ignition auxiliary marine engines (power generators, winches, or auxiliary propulsion engines for sail boats) are defined as small off-road spark-ignition engines (below 25 horsepower) or large off-road spark-ignition engines (25 horsepower and greater) depending on their size. Compression-ignition auxiliary and propulsion marine engines under 50 horsepower are defined as off-road diesel (compression-ignition) engines.

Boat engines are divided into classes of outboards or inboards. Outboard engines are those which are mounted external to the boat structure. They typically hang on the rear wall of the boat. To minimize their weight, outboard engines have traditionally been two-stroke engines, thus personal watercraft (PWC), which are most commonly two-stroke jet-drives, are grouped together with them. Inboard engines are those which are situated completely within the confines of the boat hull. Inboard boat drive types can be straight propeller-shaft, vee-drive, sterndrive, (also called inboard-outboard), or jet-drive. Inboard engines are automotive engines adapted for use in boats.

In 1998, the Board approved emission reductions from outboard engines and personal watercraft by adopting exhaust emission standards for new engines. Starting in 2001, all new outboards sold in California will be required to meet the U.S. EPA 2006 emission levels (approximately 75 percent reduction from uncontrolled levels).

The ARB has recently adopted emission regulations for new spark-ignition inboard engines.

Emission from recreational marine compression-ignition engines are the subject to of an Advanced Notice of Proposed Rulemaking (ANPRM) by the U.S. EPA (65 FR 76797, December 7, 2000). The standards are likely to be similar to the commercial marine diesel standards of 40 CFR Part 94. For more information regarding this federal regulation please see U.S. EPA's Office of Transportation and Air Quality website.

Inboard / Sterndrive At its July 26, 2001 public hearing, the Board approved, with modifications, the staff's regulatory proposal for inboard gasoline boat engines. Beginning with the 2003 model year, inboard engines introduced into California will be required to meet exhaust emission standards, certification test procedures, new-engine and in-use compliance provisions, consumer provisions such as environmental labeling,and warranty requirements.
Outboard / PWC The new California regulation requires that new outboard and PWC engines meet the U.S. EPA 2006 standards for hydrocarbon (HC) plus oxides of nitrogen (NOx) in 2001. This level represents about a 70 percent reduction in HC emissions from the pre-1998 levels. In addition, the California regulation adds a very-low-emission tier for 2004 of about 77 percent reduction from pre-1998 levels, and an ultra-low-emission level for 2008 and later of about 90 percent reduction.
The new regulation also sets emission parts warranty requirements, consumer label requirements, (which enable the purchaser to readily identify the new cleaner compliant models, and the inherently lower-emitting four-stroke models), and production line and in-use testing requirements.

Cleaner Watercraft: Get the Facts

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The video illutrates the benefits of the standards adopted for outboard /PWC's that began in 2001.
The video was produced prior to the adoption of standards for inboard and stern drive engines.