On October 2, 2020, the U.S. Environmental Protection Agency (EPA) issued a final rule amending the national marine diesel engine program set forth in 40 C.F.R. Part 1042. Through the amendment, EPA is providing boat manufacturers additional lead time to install Tier 4 marine diesel engines in certain high-speed commercial vessels. Tier 4 standards — applicable to marine diesel engines at or above 600 kilowatts — were expected to be phased in between 2014 and 2017 and were based on achieving emissions reductions through aftertreatment technology, such as selective catalytic reduction. While these engines are mostly used in various types of large workboats and passenger vessels, certain engines are used in high-speed vessels that need compact and powerful engine designs. After the Tier 4 standards were fully in effect, some high-speed boat manufacturers informed EPA that they were unable to find certified Tier 4 engines with suitable performance characteristics for the vessels they needed to build.
In recognition of the limited Tier 4 engines on the market, EPA has extended implementation deadlines for qualifying high-speed vessels in two phases. The first phase extends compliance deadlines to model year 2022 for high-speed vessels meeting specified design criteria, based on vessel speed, engine power density, engine power rating, total propulsion power, waterline length, and hull construction. The second phase extends compliance deadlines to model year 2024 for manufacturers of fiberglass and other nonmetal vessels up to 50 feet long that may need additional time to redesign their boats. EPA is distinguishing the high-speed “planing” vessels covered by this rule from “displacement hull” vessels that do not face the same design and engine installation challenges. EPA has also taken steps in this rule to streamline certification requirements for Tier 4 engines to reduce compliance costs — by, for example, allowing large-volume manufacturers to use assigned (instead of derived) deterioration factors — which EPA expects will help expedite the availability of these engines on the market.