Marine Use of Low Sulfur Diesel

Posted by Alan Sorum Mar 26, 2007

The United States Department of Environmental Protection (EPA) has issued updated regulations for the use of low sulfur diesel by boaters and the marinas that distribute diesel fuel. Starting on 1 October 2007, marinas must sell diesel does not exceed 500 parts per million (ppm) of sulfur. Marine fuel currently available at most marinas can run up to 5,000 ppm of sulfur. There are two forms of the new low sulfur diesel available to marinas. They are low sulfur diesel (LSD) that does not exceed 500 ppm of sulfur and ultra low sulfur diesel (ULSD) that can not exceed 15 ppm of sulfur.

These new EPA regulations do not apply to marinas in California. California adopted a more stringent standard that required the use of only ULSD starting 1 January 2007. There is no doubt that the new sulfur standards will protect the public. They however will pose some problems for marinas and boaters. The biggest issue facing marinas is their ability to turn over existing inventories of diesel in time to meet the new requirements. Marinas should move now to plan for this change. Boaters may have issues with effect of this low sulfur on fuel systems and engines.

As we noted with the increased use Ethanol blends to meet new air quality standards, low sulfur fuel will likely affect the lives of some boaters. Potential problems in older systems could include leaking seals, leaking fuel lines, lower lubricity of the fuel and plugged fuel filters. Reducing the sulfur content of diesel also lowers its lubricating qualities and the resulting protection of engine components like injectors. Refining low sulfur diesel changes its physical properties and could reduce engine performance. Boaters may see a slight reduction in fuel economy and peak engine output.

Diesel users should consult with their marina mechanic and engine manufacturer on strategies for coping with the new fuel. ASTM International established a standard for diesel lubricity and performance labeled ASTM D975 in January of 2005. Diesel engines designed to this standard can safely use ULSD fuels.