Sophia's Law - Carbon Monoxide Law for Boaters

What you need to know and how to comply.

Sophia's Law is named for seven-year-old Sophia Baechler, who died from carbon monoxide poisoning while boating on Lake Minnetonka. Carbon monoxide (CO) is an odorless, colorless, tasteless gas that can be toxic even in very small quantities since its effects are cumulative over time. Whether inside, outside, underway or anchored, passengers of many types of boats with a motor can quickly become victims of CO poisoning. A quick inspection every time you operate your boat can save a life, carbon monoxide poisonings are preventable.

What is required for my boat?

Co Requirements graphic - follow link to open readable pdf



What you need to know: Sophia’s Law requirements


Motorboats, regardless of fuel type, with an *enclosed accommodation compartment must be equipped with a functioning marine CO detector system installed according to the manufacturer’s instructions.

Per the American Boat and Yacht Council (ABYC) standard A-24 Carbon Monoxide Detection Systems, July 2015, detectors must be located to monitor the atmosphere in the main cabin and each sleeping area. Carbon monoxide detectors should be replaced every five years unless the manufacturer states a longer lifespan. Some newer models can be used up to 10 years before the detector becomes less effective.

All gasoline-powered motorboats with any *enclosed occupancy compartment must display three CO poisoning warning stickers as directed by law.

Three carbon monoxide warning stickers and an informational brochure have been mailed to MN-registered boats 19 feet and greater.

Minnesota is the first state to require CO detectors in motorboats. Together we can lead our nation in reducing CO poisoning accidents while boating.

*terms defined below


Does my motorboat need one or more CO detectors?


Motorboats, regardless of fuel type, must have a functioning marine CO detector if they have an enclosed accommodation compartment, which is defined as a motorboat with all of the following:

  1. Designated sleeping accommodations
  2. A galley area with a sink
  3. A head (toilet) compartment

Enclosed occupancy compartment is defined as:
One contiguous space surrounded by boat structure that may be occupied by a person

If your boat just has an occupancy compartment you are not required by law to have a CO detector in the space, however, it is highly recommended for the safety of all passengers that a detector be placed in any enclosed compartment.

Recreational motorboats that have an enclosed accommodation compartment must be equipped with a functioning marine carbon monoxide detection system, installed according to the manufacturer's instructions. A marine carbon monoxide detection system must be located to monitor the atmosphere of the main cabin of the enclosed accommodation compartment; and in each sleeping accommodation or within ten feet of any designated sleeping accommodations.

Supplementing with additional low level CO monitors will alert passengers sooner of the presence of carbon monoxide which can be harmful at low levels/under 30ppm.

A detector is not required in head (toilet) compartments or in sleeping areas separated by open or non-permanent structure. 


Does my motorboat require the three warning stickers?


If you have a gasoline-powered motorboat with any enclosed space surrounded by boat structure intended for a person to enter, you are required to have the three CO warning stickers displayed. The appropriate sticker is to be placed:

  1. At the helm (steering station)
  2. In or at the entrance to any enclosed occupancy space
  3. At the aft boarding/stern area.

Warning labels approved by the American Boat and Yacht Council, National Marine Manufacturers Association, or the DNR satisfy the requirements. 

Although it is not required, motorboats with diesel engines are urged to display the stickers warning boaters of the dangers of CO poisoning especially if they also have generators or other fuel burning appliances.


How do I get my three CO warning stickers?


At no cost to the owner, the three carbon monoxide warning stickers are currently available at all MN deputy registrar locations and many marinas, marine dealers and marine repair shops. Please call the location to confirm stickers are available.

Minnesota registered boats 19 feet and greater have been mailed the three CO warning stickers and an informational brochure. The mailed stickers and included carbon monoxide brochure will help educate owners of motorboats about the danger of carbon monoxide.


Can I install any CO detector?


No, look for the words “Marine Carbon Monoxide Detector” on the detector or on the product literature.

Marine CO detectors must meet ABYC standard A-24, July 2015 which specifies that detectors must be listed for marine use, including certification by an independent party.


What about low level monitors?


The required CO detectors come with the following warning: Individuals with medical problems may consider using warning devices, which provide audible and visual signals for CO concentrations under 30 PPM. These are known as low level monitors/detectors.

Low level monitors provide additional protection which is important to at-risk populations such as the very young, the elderly, and those with health concerns. They can be used in addition to the required detectors to provide early warning to low levels of carbon monoxide. They cannot be used as the only detectors as they are not designed for the harsh outdoor marine environment. Supplementing with a low level CO detector will alert passengers of the presence of lower, but still harmful, levels of carbon monoxide.


Can I install the Marine CO detector myself?


Hardwired Detectors: 
We recommend that you have a marine technician install hardwired detectors. Miswired boats could be a fire hazard and could cause electric shock and drowning when connected to an external power source. Electrical standards for boats are different from land-based standards. Installation must be as per the manufacturer's instructions.

Battery Powered Detectors: 
The boat owner may self-install by carefully following the manufacturers’ installation instructions, including the detector's location placement.


When do I need to replace my CO detector?


Sensors within CO detectors have an average lifespan of 5-7 years. Newer models may have a longer lifespan, and they will also have a printed expiration date or alert system notifying the user when to replace the system. When the CO detector reaches the end of its lifespan, it will become less effective at detecting carbon monoxide and should be replaced.


What are the requirements for sailboats?


If your sailboat is equipped with a motor you would be required to comply with the requirements of the law. (See the "What you need to know..." tab)

MN Statute 86B.005 defines motorboat as a watercraft propelled in any manner by machinery, including watercraft temporarily equipped with detachable motors.

The carbon monoxide warning stickers are only required for gasoline powered motorboats. Although not required, it is highly encouraged to attach them on diesel powered boats and boats with generators or stoves. The helm and stern stickers are recommended on any motorboat.


My boat is under 19 feet long, do I need to comply?


This law applies to all motorboats regardless of length that have the enclosed spaces. However, the warning stickers and informational brochure were sent to owners of motorboats 19-feet and greater. Owners of smaller boats with enclosed spaces will be able to get the stickers at all deputy registrars and many marinas or marine dealers.


What is the penalty if I don't comply in time?


The first violation will be a safety warning; additional violations are a petty misdemeanor.


My motorboat does not have a fully enclosed space, what safety steps can I take?


All boaters are encouraged to display CO warning stickers at the steering station and on the stern even if not required by law. If your motorboat has a three-sided enclosure or you operate with a canvas enclosure, please install a CO detector and warning stickers for the safety of your passengers and yourself. If your boat is diesel powered it is also in best practice to display the CO warning stickers.


What if I have an out-of-state or documented boat?


The law applies to any motorboat, with the spaces defined above, operating on Minnesota waters. This includes the Minnesota side of border waters and federal waters within the state. A motorboat includes sailboats with motors and documented boats.


For more on how to protect yourself from the dangers of carbon monoxide while boating please visit the following websites:

For information on how to get a free vessel safety check, visit or contact your local U.S. Coast Guard Auxiliary or United States Power Squadrons.

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