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New EPA mandates force new approaches

Some manufacturers are developing entirely new fuel systems to meet emissions regulations


Marine fuel tank manufacturers are using different strategies to help boatbuilders meet the Environmental Protection Agency’s new evaporative emissions regulations.

Attwood Corp., for example, is developing an entirely new fuel system it says will be relatively easy to install. Inca Molded Products is letting boatbuilders decide if they want to continue purchasing individual components on their own. And Florida Marine Tanks falls somewhere in between.

“They’re all thinking about fuel systems,” says John McKnight, director of environmental and safety compliance for the National Marine Manufacturers Association.

In October, the EPA approved new evaporative emissions rules for gasoline marine engines and boat fuel systems. The regulations address three boat fuel line issues that have never been dealt with: fuel permeation through rubber hoses, fuel permeation through plastic fuel tanks, and diurnal emissions released from the expansion of fuel vapor in the tank.

Carbon canisters
Hose and tank manufacturers already have new products on the market that address the permeation standards. McKnight says the biggest challenge for boatbuilders is controlling diurnal emission – evaporative emissions that are released through the boat’s fuel tank vent due to the daily cycle of liquid fuel becoming fuel vapor during the daylight hours and condensing during the night.

This will require a carbon canister between the vent line and the fuel tank to capture gasoline fumes and cut down on pollution. In the open fuel lines now used in boats, the fuel turns to vapor as it heats up during the day and emits into the air. The carbon canister captures those vapors. As fuel cools at night, it returns to liquid form. The cooling temperature creates a small vacuum effect and sucks the recondensed liquid back into the tank, according to McKnight.


The EPA regulations will require 50 percent of boats to have canisters by model year 2012, and 100 percent by model year 2013. “We’re in the developmental stage,” says Robert Porter, owner of Inca Molded Products. “We’re looking at the tank and the components and how it all fits together.”

Inca is working with canister manufacturers to help boatbuilders develop their own fuel systems tailored to the needs of each boat model. Porter says his company will let boatbuilders decide if they want to purchase the canisters through Inca or directly from the canister manufacturer. However, he says Inca is not using the same systems approach other tank manufacturers are pursuing.

“I don’t know if the one-size-fits-all approach will work” he says.

Joint venture
At the other end of the spectrum is Attwood, which is partnering with Stant Corp., a leader in fuel systems for cars. The two companies are working together to develop a new system for boats that Attwood says will address all the EPA requirements and ultimately make installation easier for the builders.

“We look forward to offering boatbuilders a one-stop fuel system that meets both the functional and regulatory requirements while improving their customers’ boating experience and reducing boating’s impact on the environment,” says Brian Scott, category manager for fuel systems at Attwood.

“Fuel systems today are simple,” he explains. “The deck fill feeds into the fuel hose, into the tank and then vents out.”

That’s where the evaporative emissions come from.

Also, while refueling spillage is not being specifically addressed by the EPA mandates, it will have to be addressed as a result of the carbon canisters.

“When the tank is full, the fuel can spill out — gas can fill the vent line and spill out the side of the boat,” says Scott.

“With the new rule … those things really can’t happen,” he says. “Gas can’t come into contact with the canister; it can’t travel up the fuel line into the canister. And water can’t come into contact with the canister.

“Our system will prevent water from traveling up the fuel line,” says Scott.

The system Attwood and Stant are developing will include the deck fill, fuel tank, canister, vent and everything in between. Scott says boatbuilders no longer will have to buy separate components from different companies.

“Attwood will be able to provide one solution,” he says.

Just in time
NMMA’s McKnight says there are some advantages to this systems approach. “With the whole systems kit, builders just have to install them,” he says. “That allows for ‘just-in-time’

Another company taking the systems approach is Florida Marine Tanks, although not quite to the extent of Attwood. Orestes Monterrey says his company (which builds aluminum tanks that are not subject to permeation rules) is designing a fuel system that will include the canister, a liquid vapor separator and the fuel tank, but not the hoses.

He says Florida Marine Tanks will design each system according to what the boatbuilder requests.


“It’s pretty much what the boatbuilder wants for a system,” says Monterrey, the company’s engineering manager. “It’s going to be customized for each boatbuilder. There are different sized canisters based on the size of the tanks and the boat.”

Attwood’s Scott says the marine industry is going to go through many of the fuel system design changes automakers underwent several decades ago.

“The automobile industry has had this technology for 25 years because of mandates,” he says. “Boats didn’t have those mandates.”

Until now.

Scott, however, points out there are differences between cars and boats and the fuel system requirements for each. He says one of the biggest differences is fuel systems in boats are not pressurized.

The pressurized system in a car delivers fuel directly to the engine injectors. This type of closed system prevents air or fuel from escaping the tank during operation. But these pressurized systems are prohibited on boats because if the system were to fail, fuel would collect in the bilge and could spew out everywhere.

Vent redesign
The fuel system on a boat includes a vent to allow air to move in and out of the tank during fueling and regular boat operation. The vent also allows for fuel expansion when temperatures rise. The problem is fuel and air can escape through the vent.

“We have to redesign the venting system on the tank so we have 5 percent ullage space, so the vapor has space to expand to and won’t balloon the tank,” says Monterrey from Florida Marine Tanks. While the company’s aluminum tanks must meet diurnal requirements, they are exempt from the permeation regulations because aluminum tanks don’t permeate.

Another major difference between cars and boats is that fuel tanks used in cars are blow-molded, while the marine industry uses roto-molded tanks. The material is different, so the interfaces are different, Scott explains.

Despite those challenges, however, Scott says the transition should be “relatively simple” for boatbuilders.

Monterrey agrees. “It’s not that complicated,” he says. “We’re ready for boatbuilders to say ‘Let’s go with it.’ ”

The tank manufacturers say they already made some progress last summer and fall preparing for California regulations that took effect last month. The California Air Resources Board requires that a boat with an engine that exceeds 500-hp be equipped with enhanced evaporative emission controls on fuel systems to limit the escape of hydrocarbons.

Ensuring compatibility
With the new federal regulations, tank manufacturers plan to work collaboratively with boatbuilders on fitting these systems into their boats. This includes making sure the system is compatible with the boats, making sure the tanks fit, and figuring out where the canisters will be located.


Scott says the goal is to make sure its fuel systems are in compliance, relatively easy to install, function appropriately, and are cost effective.

“I don’t think it’s going to be a huge challenge, but people still need to be thinking about it,” he says. “It’s difficult for boatbuilders to just flip the switch. We need to be a year ahead so people can make more of a gradual transition.”

To meet the model year 2012 requirement, he says Attwood will need to design these fuel systems and make them compatible with boats at least a year ahead of that deadline. Scott says the company will have a system ready for demonstration later this year and available for sale by mid-2010 — in time for model year 2011.

This article originally appeared in the February 2009 issue.



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