Hidden Dangers Result in Carbon Monoxide Poisoning while Boating

Carbon monoxide poisoning while boating results from design flaws in boat exhaust which are not clearly obvious to most boaters.

By Rebecca Martin

In recent years the speed of the propagation of half-truths has increased dramatically due to social media. The reason I am not referring to such information as misinformation is that it is often based on some event which rapidly comes into public view with very few details; either intentionally or unintentionally. These are often statements which we repeat to others as though they were verified facts meant to prove a point.

carbon monoxide poisoning while boating

One of the serious dangers of carbon monoxide poisoning while boating is that seating areas are designed near the rear of the boat, including cup holders.

One such snippet of information which comes readily to mind is the McDonalds hot coffee incident in which a customer was burned by a cup of hot coffee. This incident made it into our daily conversations usually to prove the point of frivolous lawsuits. We are prone to accept these examples of human shortcomings without question or without any knowledge of what is behind them. But when we delve deeper into the facts, we discover that a financial decision was behind raising the temperature of the coffee being served to increase the profit per cup by pennies which added up to a substantial sum and that the victim in this case suffered third degree burns as a result.

The lawsuit no longer seems so frivolous when we understand the circumstances behind this news story. The public is inclined to remember headlines, and not the facts.We also have a strong inclination to adopt a “buyer beware” attitude when it comes to product liability. And we often find it amusing that certain products bear what we feel are unneeded warnings. We scoff at warnings such as not using a blow dryer in the shower or not consuming certain products not meant for consumption. Yet the dangers the public encounters are often easily diverted by minor changes.  Take for example, the railing design at the exits for school buses. Several children were dragged to their deaths when the hood ties in their jackets hooked on bus handrails. Concerned parents discovered a simple inexpensive part which was easily installed which would prevent future deaths. And warning labels are also an inexpensive and easily applied deterrent to danger. Warning labels are reactions to events which have happened.

I was thinking of this introduction after a recent conversation I had. I was talking to a neighbor who owns a boat about my topic for my article. When I described an example of carbon monoxide poisoning in boating, I mentioned the dangers of sitting on the rear swim platform. His response was “Doesn’t everyone know not to sit on the swim platform when the engine is running?” This made me think of growing up on the ocean in Alaska. For years, we owned a boat as the sole means of transportation. My dad took a boat to work in the morning. I spent a good portion of my childhood and teenage years on one type of boat or another. Yet not once was I warned to stay out of the back of the boat while we trawled for salmon or halibut for endless hours. Until I started researching the topic a year ago, I was completely unaware of the dangers of carbon monoxide poisoning while boating. I cannot recall one drowning incident in which carbon monoxide poisoning had been mentioned as a possible cause. Now, thinking back it makes me wonder if what we didn’t know then might be looked at very differently today and how many lives might have been saved over the years.

In my previous blogs about the dangers of carbon monoxide poisoning while boating I had mentioned the fact that it wasn’t until around 2000 that the possibility of carbon monoxide poisoning from rear ventilation was brought to light. This occurred because of a study of boating deaths on Lake Powell in the Glen Canyon National Recreation Area in Utah. Several deaths came to the attention of the National Park Service and the US Department of the Interior. The studies revealed that many deaths attributed to drowning were directly connected to the lethal build up in carbon monoxide through exposure to exhaust. This could occur near or under a swim platform or near any exhaust system, and it could also occur in the cabin due to atmospheric conditions, defect or leaks or through improper venting.

In trying to understand the risks of carbon monoxide poisoning while boating, boats from many manufacturers were examined and the problem was found across the board. Concentrations of carbon monoxide were often found which were too high for detectors to accurately measure. A consensus was reached that the solution to the problem would be for manufacturers to produce cleaner burning engines.

A concerted effort was made to not only educate the public to the dangers of carbon monoxide poisoning while boating, but also first responders and emergency room staff.

Two decades later, we are still reading tragic headlines of deaths or injury due to carbon monoxide poisoning while boating. In these cases, warning labels have failed to provide adequate warning to the public. According to the U.S. Department of Homeland Security and the United States Coast Guard, since 2001 boating deaths have risen. In 2020, 75% of fatalities from boating accidents were labeled as drownings and 86% of those were not wearing a lifejacket. In 2020, 5 deaths were directly attributed to carbon monoxide poisoning. Deaths attributed to what appear to be natural causes are not included in boating accident statistics. Deaths in which alcohol is involved are attributed to alcohol use. 41 incidents of non-fatal carbon monoxide poisoning were reported in 2020.

However, the 2000 study found a correlation between undiagnosed carbon monoxide exposure and drowning. They further found that the incidence of carbon monoxide exposure in non-fatal incidents was significant and surmised that many such incidents go unreported as carbon monoxide poisoning mimics the symptoms of other illnesses as well as often being attributed to alcohol consumption.

Drownings from carbon monoxide poisoning while boating

Let’s take a closer look at drowning incidents from the public perspective:

Boating was on the rise last year due to Covid-19. More people were enjoying boating as a means to enjoy socially distanced recreation. More people had flexible work schedules which allowed for more recreation time. Boat sales were on the rise and more first time boat owners were taking to the water. In May, 2020, the boost in sales was reported as a 75% increase over 2019 with some dealers reporting a 300% increase in sales. First time boat owners weren’t only buying new boats, they were buying pre-owned boats as well. It was a seller’s market with demand overwhelming supply throughout the lockdown. Boating was touted as being one of the best ways to enjoy the summer during lockdown. But were boat owners as knowledgeable as they should have been about carbon monoxide? Was access to boating instruction restricted due to Covid? Those are questions that may continue to plague us for the post-lockdown years.

Safety from Carbon Monoxide poisoning while boating an Illusion

One of the reasons that we feel safe from carbon monoxide on a boat is the illusion that being in the fresh air makes carbon monoxide poisoning impossible. Carbon monoxide is odorless. And it is a fast killer. We also feel safe in the belief that our boats have a venting system designed for human occupancy and under any conditions. But carbon monoxide poisoning is one of the top five causes of death while boating  annually according to the U.S. Coast Guard.

A recent story at Today.com tells a family’s story of the death of their 21-year-old daughter in May. Their daughter was an experienced swimmer, which added to the confusion surrounding the reported drowning death. It was later determined to be carbon monoxide related. The truly interesting thing about this case is that upon examination this boat model had seats and cupholders in the back end of the boat and the Yamaha owners’ manual states

“Passengers must always sit in a designated seating area.” https://www.today.com/health/boat-carbon-monoxide-poisoning-woman-21-drowns-lake-trip-t229191

Swim Platforms are Serious Design Flaw

Although the owners’ manual warns about sitting on the swim platform during the boat’s operation and diagrams safe seating areas, it is hard to reconcile the presence of seating in an area determined to be unsafe during the boat’s operation.  Today went on to test that area with a carbon monoxide detector and within a few minutes it had spiked to 700 parts per million. They also measured the air around idling boats in the area and found readings of 400 parts per million. For one of our prior blogs on carbon monoxide poisoning while boating, click here.

Another, not uncommon thread, involves extensive ‘No Wake’ zones. These are long stretches of water where boats are required to idle or drive at a speed only sufficient to propel the boat forward. They exist for many reasons; to protect residential properties, to protect people in the water,  to protect structures such as overpasses or bridges, to slow traffic when approaching a water intersection, or to protect wildlife habitat.

A No Wake zone was part of the story in June, 2020 when a family was returning from a day on the water with tired, cranky kids on Lake Eufaula in Oklahoma. With 20 years of boating experience, they never dreamed their youngest son would fall victim to carbon monoxide poisoning. When Andrew had curled up to sleep in the back of the boat they attributed his complaints to too much sun. Their other children were also complaining of headaches and nausea. Upon docking and attempting to rouse the kids, Andrew rolled off the back of the boat and by the time he was rescued, he was unresponsive and it was too late. According to the September, 2020 article on Today.com, Andrew’s mom said:

“People need to understand, we are experienced boaters. My husband has almost 40 years and I have been boating for almost 25 years. We had a friend with us, she had been boating another 30 or so years.”

And although they were competent, they were all unaware of the danger of carbon monoxide poisoning on a boat. “None of us had ever heard of it. None of us had considered it,” she said. “We were stunned.”

Boat Cabins can accumulate Toxic Fumes

Rear exhaust exposure is not the only hazard in boating. In July, 2021 the Coast Guard was asked to respond to a report of a boat circling the Cleveland crib water intake in downtown Cleveland. Upon arrival the Coast Guard broke a window to gain access to the cabin and discovered two men deceased on the scene and a minor who was found to be unresponsive. The boy eventually succumbed to carbon monoxide poisoning  in the hospital. Witnesses had reported that the boat’s engines were running. First responders had reported a carbon monoxide detector which was sounding.

In August, 2021, four people were injured and one died due to carbon monoxide poisoning aboard a cabin cruiser on the Lake of the Ozarks.

Anytime combustible fuel is present, the potential for carbon monoxide exists. There have been many attempts to bring the relevant information to the public throughout the past few years.  Many such endeavors are fueled by the surviving family members of those who have perished. Efforts have been towards boat manufacturers themselves to modify systems which have performed poorly under certain non-ideal circumstances, to redesign exhaust systems and to move towards cleaner burning engines which produce much less carbon monoxide. Many efforts have been made to educate the public and to insist that those in the business of selling boats educate their customers.  Tremendous efforts have been made to educate first responders to the scene of a boating accident to consider carbon monoxide as a possible factor and for medical personnel to rule out carbon monoxide through appropriate testing.

As always, one of the easiest and most inexpensive guardians for boaters are marine carbon monoxide detectors, specifically designed for marine environments. Most marine detectors are under $100 and the benefit they provide is priceless.

Know the symptoms of carbon monoxide exposure and don’t take them lightly. Symptoms can include: headache, confusion, fatigue, nausea, dizziness and ultimately seizures and unconsciousness. There is a tremendous page for boating carbon monoxide safety at https://www.uscgboating.org/assets/1/Publications/co_brochure_0105.pdf

This is a brochure in a pdf format for marina operators everywhere. It includes checklists to insure that every trip is a safe one, including maintenance checklists to make sure engines and generators are operating properly. This brochure is a must have for boaters, especially all of those first time boaters who took to the water during Covid. But as you have seen, even long term boaters can learn more about carbon monoxide safety.

One of the important points in the brochure is educating everyone embarking on a day on the water as to what the symptoms are and to react immediately if carbon monoxide can’t be ruled out. This means getting them to fresh air, shutting off any fuel burning devices and opening doors and windows if applicable. If carbon monoxide exposure is suspected, seek medical care. When carbon monoxide levels are elevated, even a few breaths can injure or kill you.

As I said at the beginning of this article, we are exceptionally clever at putting safety warnings in the half-truth column and minimizing the issue of public safety. Often manufacturing companies are happy that these half-truths exist to put the burden on the public in order to safeguard profits. But, as members of the public, we are also accountable to each other to continue to spread information that might ultimately save lives. Education goes a long way to extending the reach of warning labels.

When my neighbor said “Doesn’t everyone know that you can’t sit on a swim platform while the engine is running?” I responded “No, no they don’t. And my job is to let them know’”. I hope the takeaway is that we let everyone know why and how carbon monoxide can kill.

Happy and safe boating and please check out the U.S. Coast Guard brochure at:





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