In 2011, sweeping reforms were made to the EPA fuel emission reduction guidelines.  These changes had huge and significant effects on the marine industry, causing substantial changes to the engineering of the fuel systems that are used on boats.  These changes improve the safety of boat fuel systems, but also increase the overall cost of the systems, sometimes as much as 100%.  The three main facets of the 2011 EPA regulations are low permeation, evaporative emissions and anti-spitback requirements.

Low Permeation

The fuel that you use in your boat is constantly emitting invisible hydrocarbons into the atmosphere.  These hydrocarbons are extremely pollutant and harmful to the environment.  Even when fuel is contained inside your boat's fuel system, hydrocarbons are able to travel through the walls of a plastic fuel tank or a rubber fuel hose.  The 2011 EPA regulations (which are part of the Clean Air Act) set new maximum levels for how much hydrocarbons are allowed to permeate from a boat's fuel system.  Depending on the size and type of vessel, those maximum levels can vary.

In order to be efficient, most hose and tank manufacturers have elected to produce products which meet the most stringent EPA permeation standards.  This usually includes reinforced outer barriers to contain much of the hydrocarbons that are emitted from fuel.  For instance, Moeller Marine introduced a two-layer outer barrier to all of its below-deck fuel tanks to meet these new standards, and all of their portable and above-deck tanks were redesigned with nano-particle–infused high density polyethylene to better prevent hydrocarbon permeation.  All boatbuilders have been required to meet these permeation standards since 2011, and most aftermarket tanks and hoses now carry the EPA certification.

Evaporative Emissions

Prior to 2011, all marine fuel tanks were open-vented to the atmosphere, releasing a lot of hydrocrabons into the environment.  The 2011 EPA regulations required a change in this approach.  The new standard requires all emissions to be controlled by either a carbon canister or a sealed pressurized fuel system.  In many cases, people refer to the canister system as an "open" system and the pressurized system as a "closed" system.

In the canister-style or "open" system, fuel vapors are only exposed to the outside atmosphere without filtering during the time fuel is being put into the system.  Fuel vapors flow through the fuel tank and then are captured in a hydrocarbon canister.  The hydrocarbons remain trapped in the canister until the incoming flow of fuel moves them into the fuel system, where they are burned up during the engine combustion.  This is the type of system that has been used in the automotive industry for decades, and the benefit is that you are not operating the fuel system under any sort of pressurization.  However, a canister-style fuel system requires venting from the canister to the outside of the boat.  This usually requires extending the vent through the hull of the boat and terminating in a P-trap.  A canister-style system can also require long lengths of hose and design features that will prevent fuel from entering the canister during refueling or when the boat tips substantially.  The canister can also clog or become contaminated and require maintenance.

In a pressurized or "closed" fuel system, the fuel vapors only escape to the outside of the boat during times when fuel is being filled or when the pressure inside the system breaks the seal of a fueldeck fill valve or fuel cap.  Once the vapors are released, these seals should reseal to pressurize the system once again.  The requirement is that the fuel system be pressurized up to 1 PSI.  Once the pressure inside the system exceeds 1 PSI, then the fuel cap or fuel deck fill would vent until the pressure reduces below 1 PSI.  Most of the time, the pressure in the system stays below 1 PSI and does not require venting.  This system is less expensive than a canister-style system because it requires less parts.  The maintenance issues that come with a canister are non-existent in a pressurized system, and so it is typically more reliable than a canister-style system. However, operating a pressurized system adds some additional safety concerns, and it is important that any user is aware of the pressurization and takes certain precautions whenever filling or maintaining the system.

Anti-Spitback

The requirement of anti-spitback of fuel during the filling process not only is environmentally beneficial, but also saves money and prevents mess.  Previously, boat owners would frequently overfill marine fuel tanks until fuel overflowed through the deck fill vent, spilling fuel into the vessel or into the water.  After the 2011 EPA regulations, marine manufacturers adopted many design ideas from the automotive industry to prevent spitback of fuel, including fuel limit valves on the tank and flapper-style check valves on the inlet hoses of the tank.  These features ensure that fuel backs up and trips the aspirator in the fuel nozzle, stopping the filling process similar to how a car is filled.

 

While there was certainly initial frustration with the stringent requirements instituted by the EPA, the marine industry has adapted well to the new standards, and now all boats are manufactured with these standards in place.  There may be some additional cost and some additional maintenance required for your fuel system than there was in the past, but the overall benefits to the environment have been improved greatly, making boating a cleaner and more enjoyable pastime for all.

If you have questions about the fuel system on your boat, please give the ABYC-certified experts at Marine Parts Source a call at (866) 388-0390!