Boat Carbon Footprint

Information Center

Calculate My Boat Carbon Footprint

Boat carbon neutral, boat carbon offsets, boat carbon credits, calculating your boat carbon footprint, minimizing your boat carbon footprint, boating green and related boating engine emissions and environmental issues are covered here. If your boat has a gas or diesel powered outboard motor, stern drive, or inboard motor it has a carbon footprint.

Boat Carbon Footprint Information Center is a Polson Enterprises web site.

If you become aware of any information you think would be useful for our readers that is not listed on this site, broken links, or have any comments about our site, please email us.


Carbon Monoxide v. Carbon Dioxide

Your boat's engine emits both Carbon Monoxide (CO) and Carbon Dioxide (CO2) in the exhaust. Both are bad for us. Carbon Monoxide is an odorless, colorless toxic gas. It causes breathing (respiratory) problems and smog. Carbon Dioxide, also odorless and colorless, is a major contributor to global warming.

Carbon Monoxide is formed when fuel does not burn completely. Much of the automotive emission work in recent years has focused on reducing Carbon Monoxide emissions. One early approach was injecting air into the exhaust to burn the remaining fuel (sometimes called a smog pump). Today, Electronic Fuel Injection (EFI) is used to reduce CO emissions by burning fuel more completely. Catalytic convertors are another tool for reducing Carbon Monoxide. Just a few years ago, Carbon Monoxide was identified as a deadly hazard on houseboats, especially when people swam or floated near the stern swim platform when the generator was running.

Carbon Dioxide is a direct product of the amount of fuel burned and the only way to reduce CO2 emissions is to reduce consumption of hydrocarbon fuels. U.S. automotive fuel mileage standards have remained relatively flat for many years. Much of the fuel combustion and exhaust gas work has focused on reducing emissions of the smog causing gas, Carbon Monoxide. In recent years, Ethanol has come on strong in the automotive industry and is currently making a push in the boating industry, but having a few problems (like dissolving fiberglass fuel tanks, mixing ethanol and MTBE of standard fuels, ethanol attracts water, etc. ). Alternative power sources (fuel cells, hydrogen, hybrid engines) are making noise in the automotive industry but just being discovered by the boating industry.

What is a Carbon Footprint?

Just like we leave footprints in the sand, our actions leave footprints in the environment. One of those footprints is how much carbon dioxide or CO2 is emitted by the combustion of fossil fuels to support our daily lives. Carbon Dioxide is a major component of the Greenhouse Gasses warming our planet. By being aware of our Carbon Footprint we can begin to reduce it and thereby reduce our impact on the planet.

Carbon footprints can be calculated for certain activities (flying from here to Washington DC on a commercial jet, driving 20 miles in the family car, boating the afternoon away in our family boat, and other activities). Our total impact on the environment is the sum of all those events, plus the utilities in our home, the food we eat (farmed), the impact of shipping many of the goods we consume, and the packaging of those goods. Several studies place the average American's CO2 emissions at about 20 tons a year (110 pounds a day). With some thought and careful choices we can significantly reduce our carbon footprint.

What is Boat Carbon Footprint

Boat Carbon Footprint is the emission of CO2 from fossil fuels during the use of your boat. These emissions primarily come from burning fuel in the engine(s). Yes, additional CO2 emissions may be generated by a tow vehicle, the use of a generator on the boat, the consumption of food and beverages and other activities. However, if you were not boating, you might well be driving around some, consuming food and beverages and other similar activities, so it is realistic to calculate your Boat Carbon Footprint as the impact of burning fuel in your engine(s) including a generator.

Yes, we know many boats eject their exhaust under water through the prop, but the gasses still rise from the water to the atmosphere.

Calculating Boat Carbon Footprint

Your boat's carbon footprint is directly proportional to how much gas it burns a year (boating season). One gallon of gasoline is equal to about 20 pounds of CO2 (actually 19.564 pounds).

How does one gallon of gas that weighs about 6.3 pounds create 20 pounds of Carbon Dioxide?
When gas burns it combines with many times its weight in oxygen and becomes much heavier. See for the scientific explanation.

To calculate the Carbon Footprint of Your Boat you need to determine how much fuel it consumes in a year. There are several approaches.

  • Write the number of gallons purchased on your fuel purchase receipts and and add them up at the end of the year.
  • Keep good records for one typical boating outing and multiply the gallons consumed by the typical number of boating outing you make a year.
  • Identify your boat motor and use average fuel consumption estimates for it (or twice it if you run twins)
Don't forget to include kicker motors, generators or other fossil fuel engines on your boat.

We are currently working on some tables for average boat motor fuel consumption by manufacturer and model number. See our work on the Boat Annual Fuel Consumption Page

Minimizing My Boat Carbon Footprint?

There are two ways you can reduce your boat carbon footprint: (1) actually reduce your fuel consumption, (2) you can offset your boat carbon footprint by reducing your carbon footprint in other areas.

Directly reducing boat fuel consumption can be accomplished by:

  • Taking it a little easier on the throttle (don't be a jack rabbit, at least not all the time)

  • Pull the throttle back from WOT (wide open throttle) to Cruise at least twice more per boat outing.

  • Lighten up your boat. Go over it with a fine tooth comb before the season and throw out everything you don't really need. Then do it a again at least once a month during the boating season. Excess weight drastically effects fuel consumption.

  • When buying a new or used boat, make sure the engine is properly sized and one of the new more efficient models.

  • Do not buy a carburated motor. They are much less efficient than the newer generation motors.

  • Get on plane quickly with planing boats. Don't keep slugging through the water with high resistance when the hull is fully in the water (except in no wake zones, manatee zones, or other posted areas).

  • Learn to use power trim (trim in for getting on plane and out for cruising)

  • Eliminate unnecessary idling.

  • Make sure your boat is properly propped and your propeller is free of dings

  • Consider installing a stainless steel propeller (usually thinner blades resulting in same speeds at less rotating drag meaning less fuel consumption)

  • Install an electronic fuel meter if you do not have one. Use it to monitor fuel consumption and establish your optimum cruise speed.

  • Follow the engine manufacturer's recommended maintenance schedule.

  • Don't carry excess fuel and water. (Water weighs about 8 pounds per gallon and gasoline weighs about 6.3 pounds per gallon)

  • Keep your hull clean - spray wash it and re-paint it as necessary to reduce drag

  • Invite some friends to go boating with you (just like carpooling, more people to split the emissions among - others are able to participate in the boating experience without adding more carbon dioxide to the atmosphere).

  • If you have a larger boat making longer runs, consider installing an autopilot. Keeping closer on course will save fuel.

  • If "speed" is your thing, get a smaller boat. Smaller boats can go much faster on less fuel.

  • Consider a pontoon boat. They offer a lot of space and fishing opportunities and generally don't burn a lot of fuel.

Other Boating Choices Offset Boat Carbon Footprint

You can offset some your remaining boat carbon foot print by reducing the carbon footprint of other activities during your boating outings:

  • Avoid spilling gasoline.
  • Use a funnel or a spout with an automatic stop device to prevent overfilling the gas tank.
  • Close the vent on portable gas tanks when the engine is not in use or when the tank is stored.
  • Transport and store gasoline out of direct sunlight in a cool, dry place.
  • Use caution when pumping gasoline into a container at the gas station.
  • Use an efficient tow vehicle if you have a trailer boat.

  • Keep your vehicle and boat trailer tires properly inflated or they will reduce your gas mileage.

  • Buy food and other products with less packaging (less waste) that come from local destinations when possible (reduce trucking emissions)

  • Prepare your own meals and eat out a little less while boating.

  • If you choose to bar-b-que grill a meal, it seems uncertain whether charcoal or propane is the best environmental choice per a 13 June 2007 AP article in Lower Hudson Online titled, Green Grilling - Gas vs Charcoal

  • Reduce your use of battery powered products. If you have to use electronics, plug them in when you can to reduce use of batteries.

  • Keep your boat battery properly charged and maintained to increase its life.

  • Buy one of the new super insulated ice chests and keep it in the shade to reduce your use of ice.

  • Be sure to turn up the thermostat on your home air conditioner while your family is gone boating.

  • Minimize use of on board air conditioners. Use fans when you can instead.

  • If your tow vehicle is a pickup, leave the tailgate down when you can to reduce drag (fuel consumption) or get one of the "tailgate nets" or one of the new tube type that can flip up)

Remember, the goal is not to make boating a painful experience. Boating is supposed to be a fun experience away from everyday life. Don't make it a drudge by being too restrictive on your Boat Carbon Footprint. There are still more ways to reduce your impact on the environment. They will be discussed below.

If you have any other boating related tips to reducing your boat carbon footprint, please email them to use and we will post them here if appropriate.

Life Style Changes Offset Boat Carbon Footprint

You can also offset your boat carbon footprint by other decisions you make in daily life, such as:
  • Increasing your use of public transportation
  • Turning your thermostat down in the winter and up in the summer
  • Driving efficient vehicles, especially if you commute considerable distances to work
  • Making sure your home uses Energy Star efficient appliances
  • Switch your home's light bulbs to the new energy saving fluorescent ones
  • Turn the lights off when you leave a room
  • Turn the TV off when you leave the room
  • Make sure your home is well insulated
  • Bike, walk and carpool
  • Cut down your consumption of goods in general
  • If you are considering buying a new vehicle, check out EPA's Green Vehicle Guide
  • Become active in community affairs and try to protect trees remaining in your area when they can be saved from developers without undue hardships being placed upon those developing the land.

  • Get out in the countryside now and then and breathe the fresh air. It will motivate you to better manage your carbon footprint.

Again, remember life is supposed to be fun too. Don't be too hard on yourself. Just make some minor changes and the results will poor in long term just like interest on money in the bank.

Offset Remaining Boat Carbon Footprint

Lastly you can take special actions to offset your boat carbon footprint, such as:

  • Plant a tree. The average tree absorbs about a ton of CO2 over its lifetime.

  • Several tree planting organizations (plant trees for you) are listed on

  • Purchase carbon offsets from companies who use the money for projects that trap carbon dioxide or reduce its generation. These projects include helping wind farms get up and running (vs. less costly coal fired plants), rescuing huge acreages in South America (it doesn't matter where it happens, gasses eventually equalize around the globe), Control methane emissions on dairy farms by burning it and producing energy (methane is said to be about 22 times more "potent" than Carbon Dioxide as a greenhouse gas), setting up landfill methane gas flaring operations, and encouraging the growth of Plankton in the ocean.

The process of trapping Carbon Dioxide from the environment, such as in trees, is sometimes called Carbon Sequestration.

To minimize your impact on the environment we suggest you try to approach boat carbon neutral, meaning you minimize the Carbon Dioxide emissions of your boat, then reduce other Carbon Dioxide emissions during your boating activities, make some lifestyle changes to further reduce your Boat Carbon Footprint, then offset the remaining carbon dioxide by planting trees, participating carbon offset projects, or other similar actions to neutralize your boat carbon footprint.

Boating allows us to experience the environment, lets take good care of it so our children and grandchildren can too.

Catalytic Converters Create Carbon Dioxide

Catalytic converters pass the remaining fuel and Carbon Monoxide (CO) in the exhaust over platinum or palladium pellets (a catalyst) to oxidize them resulting in more Carbon Dioxide, water and heat.

The big point here is that catalytic converters actually create more Carbon Dioxide.

Recently, the use of catalytic convertors on stern drives has been in the press. Indmar is now selling stern drive engines with catalytic converters and others will not be far behind in order to meet upcoming emission regulations.

We are certainly not saying catalytic converters are bad, we just fear some people may feel they are also reducing their Carbon Dioxide emissions by the use of a catalytic convertor, when in fact they are actually increasing them. The chemical equation in play in a catalytic converter is:

2 molecules of Carbon Monoxide plus 1 molecule of Oxygen = 2 molecules of Carbon Dioxide


2CO + O2 = 2CO2

Plus the catalytic converter also similarly converts unburned hydrocarbons into Carbon Dioxide and water.

Yes, many boats have high levels of carbon monoxide and catalytic converters can bring these levels down, but they are accomplishing this at the expense of producing even more Carbon Dioxide greenhouse gasses.

Attempts to Regulate CO2 in Automobiles

Marine engine emission regulations tend to follow automotive emission regulations. Automobiles have long ignored carbon dioxide emissions, but that appears about to change.

On 24 October 2007 the European Parliment has adopted by a non-binding vote, a report calling for capping average CO2 emissions from all new passenger cars by 2015.

California is currently suing the U.S. Environmental Protection Agency for a Clean Air act waiver that would allow it to enact a 2002 law regulating green house gasses.

On 19 December 2007, the U.S. Environmental Protection Agency said Califorina and the 16 other states that joined them in the lawsuit cannot set their own carbon dioxide emission standards for automobiles. Stephen L. Johnson of the EPA said the rules proposed by California are pre-empted by Federal Authority. Governor Schwarzenegger says the states will move the case on to federal court. (see E.P.A. Says 17 States Can't Set Emission Rules. New York Times 20 December 2007).

The EPA is promoting its mileage improvement program as the solution. Some suggest they ruled in the industry's favor in the California issue in exchange for industry accepting the mileage improvements which allow the industry longer to respond.

Its obvious this is coming. Is it not finally time for the boating community to look ahead instead of looking behind and begin to address this issue in the currently proposed emission regulations?

Carbon Disclosure Project

The Carbon Disclosure Project is an international non profit effort to have large companies engage in an emissions dialog, take stock of their emissions, share their status, plans and progress in reducing them. Brunswick Corporation, one of the largest boat builders in the U.S. and a major manufacturer of outboards and stern drives has declined to supply their comments in an official statement: Brunswick Corporation declines to participate in Carbon Disclosure Project

Interestingly, Life Fitness, a Brunswick Company, has a report promoting indoor exercise due to high levels of emissions and other pollutants outdoors.


Thanks to the many articles, papers and web sites below, we were able to build upon them and pull materials together specifically for boats and boat carbon footprints.

Some Other Polson Enterprises Web Sites


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