Carbureted 2-strokes may become history as EPA prepares to impose California standards nationwide
The Environmental Protection Agency’s latest emissions regulations will require some major changes for gasoline-powered marine engines and fuel systems.
The new regulations mean gasoline outboard, personal watercraft and sterndrive inboard engine manufacturers will basically be required to meet California emission standards. This will also be the first time gasoline marine engines will be required to meet a carbon monoxide standard. For boatbuilders, the new regulations will require fuel systems to meet both permeation and diurnal emission reductions.
EPA is adopting a more stringent level of emission standards for outboard and PWC engines starting with the 2010 model year, which may well spell the end for new carbureted 2-strokes.
“There are going to be challenges, but there are going to be opportunities as well,” says John McKnight, director of environmental safety and compliance for the National Marine Manufacturers Association.
“It will make boatbuilders take a new look at fuel systems and improve them,” he adds.
The standards will control evaporative emissions for all vessels using marine spark-ignition (gasoline) engines. The rules address three pollution issues around boat fuel systems that have never been regulated:
• fuel permeation through rubber hoses
• fuel permeation through “plastic” fuel tanks
• diurnal emissions, or emissions released from the expansion of fuel vapor in the tank that permeate into the atmosphere through the vent
Nonporous fuel lines
After Jan. 1, 2009, boatbuilders have to use a low-permeation fuel line to meet the hydrocarbon and nitrogen oxide permeation standard of 15 g/m2/day. However, the EPA is allowing builders to use up their existing stock of hoses.
“It doesn’t have a lot of enforcement at this point, but by model year 2010 the industry has to use up all its [existing] hoses,” McKnight says.
Older style fuel hoses are more porous, he says, and the fuel vapor molecules are able to permeate through the hose material into the air. Hose manufacturers have developed new technology by adding a barrier coat made of nylon, for example, that greatly reduces permeation.
McKnight says these newer hoses are already on the market, but for model year 2010 they must have the proper label to indicate EPA compliance.
Permeation emissions from fuel tanks may not exceed 1.5g/m2/day. The affected tanks are rotational molded plastic models and those made of polyethylene. Both types would need a barrier layer to reduce emission levels.
Portable marine fuel tanks must meet the standard by Jan. 1, 2011; PWC tanks must comply by model year 2011; and for onboard tanks, the deadline is model year 2012.
Several tank manufacturers, including Moeller Marine Products, were showing new low-permeation tanks at the recent International BoatBuilders’ Exhibition & Conference (IBEX). McKnight says manufacturers have the tanks, but now they’re trying to find less expensive ways to manufacture them.
The biggest challenge for boatbuilders is controlling diurnal emissions, says McKnight. There is one standard for boats 26 feet and longer, and one for boats less than 26 feet, based on what is considered a trailerable boat.
Diurnal emissions from Marine SI fuel tanks may not exceed 0.40 grams per gallon per day. An alternative standard of 0.16 g/gal/day applies for fuel tanks installed in nontrailerable boats.
Portable marine fuel tanks are not subject to these standards, but must instead meet the following requirements: They must be self-sealing (without any manual vents) when not attached to the engines; the tanks may not vent to the atmosphere when attached to an engine; and they must remain sealed up to a positive pressure of 34.5 kPa. They may contain air inlets that open when there is a vacuum pressure inside the tank.
Also, detachable fuel lines that are intended for use with portable marine fuel tanks must be self-sealing (without any manual vents) when not attached to the engine or fuel tank.
For PWC tanks, the EPA is recommending a pressure relief valve on the fuel tank. However, McKnight says the Coast Guard frowns on this for larger boats and tanks because of safety issues.
The other option is to install a carbon canister between the vent line and the fuel tank to capture gas fumes. By model year 2012, 50 percent of boats must have a canister, and by 2013 all must have them.
McKnight says the EPA originally proposed 100 percent compliance by 2010, but the industry was able to negotiate the slower phase-in.
“Do I think it’s feasible? Definitely,” says McKnight.
An unveiling at IBEX
Some manufacturers are already working on the technology. Attwood Corp. of Lowell, Mich., recently formed a partnership with The Stant Corp. to develop what Attwood calls “the next generation of marine fuel systems.”
“While marine fuel systems have remained relatively simple and unchanged for many years, new regulations will require a significant increase in their complexity to function effectively,” says Attwood president Chris Drees. “We cannot approach this one component at a time, but rather the fuel system in its entirety must be considered and optimized.”
Drees says Attwood is also working to solve the persistent problem of fuel spill and spitback.
Attwood demonstrated the first steps of this program at this year’s IBEX, where the first generation marine carbon canister system intended to meet California Air Resource Board requirements in January was introduced. The system will be available for sale in mid-November.
Despite the challenges of re-engineering the fuel systems on boats, McKnight says the use of canisters offers some benefits.
“It captures fumes when fueling a tank, there’s no spitback during refueling,” he says. “It’s a change for the better.”
Tank and hose manufacturers will be responsible for certifying that they meet EPA standards. And to ensure boatbuilders are using certified tanks and hoses, McKnight says EPA officials have been known to visit boat shows and dealerships. Boats not in compliance will incur significant penalties, including recall provisions.
ABYC must update
The American Boat & Yacht Council is going to have to make some changes because of the new EPA regulations as well. McKnight says ABYC has to update its own standards to comply with the EPA’s new evaporative emissions standards for boats.
“The goal is to harmonize ABYC standards with the EPA rule as much as possible,” says McKnight.
For example, the ABYC standard needs to be updated to specify that the hoses be labeled to show EPA compliance. ABYC also needs to create durability tests for the new low-permeation plastic fuel tanks, and an installation standard for canisters to prevent spitback, keep the canister dry, and make sure there is enough flow in the hose.
McKnight says the industry also may look at fill rates for boats. Automobile gas stations are required to pump no more than 8 gallons a minute, but there is no mandate for marinas. Since boats generally have much larger tanks than cars, marinas pump anywhere from 15 to 25 gallons per minute.
Adjusting fill rates for boats is not required in the EPA’s new emissions standard, but McKnight says, “That is something we need to look at.”
EPA is adopting a more stringent level of emission standards for outboard and PWC engines starting with the 2010 model year. The new standards are very similar to the CARB standards, but at a federal level.
The HC+NOx standard for engines producing less than or equal to 4.3 kW maximum power is 30 grams per kilowatt hour. Engines over 4.3 kW have an HC+NOx standard that gradually increases based on the engine’s maximum power.
McKnight says the new regulation sets a cap on family emissions of 60 g/kWh of HC+NOx. “That forever kills the carbureted 2-stroke,” he says.
The CO standard for engines producing less than or equal to 40 kW gradually increases based on the engine’s maximum power. The CO standard for engines with maximum power greater than 40 kW is 300 g/kWh. EPA expects manufacturers to meet these standards with improved fueling systems and other in-cylinder controls.
Ahead of the curve
Engine manufacturers say they will be ready for the new rules.
“We have known about these impending regulations for quite some time and have been working on the necessary technical solutions,” says Martin Peters, spokesman for Yamaha Marine Group. “Yamaha will meet or exceed all EPA regulations for 2010.”
Mercury Marine also anticipated the new standards. Spokeswoman Shannon Marone says the engine maker has already made its products compliant with CARB regulations, “so we don’t anticipate any new product changes for this particular ruling.”
She says Mercury’s conventional carbureted 2-strokes will be completely out of the U.S. market by 2010. Mercury’s direct-injected 2-stroke engines are not affected by the new standards, Marone adds.
The EPA is also adopting new exhaust emission standards for sterndrive and inboard marine engines. The standards are 5 g/kWh for HC+NOx and 75 g/kWh for CO starting with the 2010 model year. EPA expects manufacturers to meet these standards with three-way catalysts and closed-loop fuel injection.
“The new EPA regulations will require us to begin selling the catalytic converter-equipped sterndrive and inboard engines that we currently sell in California nationwide in 2010,” says Mercury spokeswoman Marone.
The EPA has deferred the standard for 4.3-liter and 8.1-liter sterndrive/inboard engines until 2011. All other engines — 3-, 5-, 5.7- and 6-liter — must have catalytic converters by 2010.
For sterndrive and inboard marine engines above 373 kW with high-performance characteristics, or SD/I high-performance engines, EPA is adopting a CO standard of 350 g/kWh.
The EPA is adopting a HC+NOx standard of 20 g/kWh for high-performance engines producing between 373 and 485 kW in 2010, followed by a tightened standard of 16 g/kWh in 2011. For high-performance engines producing greater than 485 kW, EPA is adopting a HC+NOx standard of 25 g/kWh in 2010 and 22 g/kWh in 2011.
McKnight and others say the marine industry should be able to meet all of these regulations within the respective time frames, thanks in part to negotiations with EPA on two key issues: compliance deadlines and reporting and certification requirements.
“There are no surprises here,” says McKnight. “Because the EPA has allowed sufficient time for compliance, boatbuilders will have the time and resources necessary to redesign their vessels to meet these new standards.”
Also, because there is no reporting or certification requirement for boat manufacturers, they will only be required to install certified equipment in their vessels and affix a standard label that states the vessel is in compliance with EPA regulations for the specific model year.
“One of the primary benefits the industry fought for is [a] very limited administrative burden for boatbuilders,” says McKnight.
“The rule allows us the flexibility we need to implement the required changes while helping the EPA meet their goal of reducing emissions,” says Jim Hardin, compliance manager for Grady-White Boats.
When the changes are fully implemented, recreational watercraft powered by gasoline engines will see a 70 percent reduction in HC and NOx emissions, a 20 percent reduction in CO emissions and a 70 percent reduction in fuel evaporative emissions.
“Reduced emissions will help keep our water and air clean, which is very important to both us and our customers,” says Hardin.
This article originally appeared in the November 2008 issue.