A shocking reminder of how insidious carbon monoxide can be comes from none other than legendary racing car driver Al Unser Sr. The Formula 1 driver who’s won the Indianapolis 500 four times and been around running engines his entire career was nearly killed — not on the auto racing track, but out on his boat.

Several years ago, Unser was out on a houseboat on Lake Powell, AZ, when a storm came up and he and his crew decided to pull up their anchors and move the boat away from some rocks. Once the boat was re-anchored, Unser decided to dive below the boat to unsnag another line. As he repeatedly dove and surfaced, he came up in an air space beneath the deck, unaware that the boat’s generator was vented into this air space and he was gulping down deadly levels of carbon monoxide.

Unser does not remember how he got himself back up on the deck, by then semi-conscious. Rushed to a hospital, he was put on oxygen and, most fortunately, survived the incident. He now makes a point of warning other boaters of how dangerous this odorless, colorless, tasteless gas can be.

Carbon monoxide has been a known hazard on boats for decades, particularly inside cabins on boats with gasoline-powered generators. But what galvanized education and research efforts to a more urgent level was the discovery in 2000 that many houseboats were built with a fatal flaw. Deaths that had formerly been attributed to drowning were in fact carbon monoxide poisonings of adults and kids who were swimming into an air cavity, like Unser did, filled with generator exhaust. Two boys who died, merely feet away from their parents, because they were playing under the deck, as well as other incidents on houseboats, resulted in congressional hearings and a U.S. Coast Guard recall of houseboats with this particular design in 2001.

On the heels of the houseboat recall came more testing and the discovery that boaters were also being overcome in “fresh air” poisonings, sitting in cockpits, on stern decks and swim platforms. Consequently, public education efforts have been ramped up to warn boaters of this unseen hazard, but a push on another front — technology — could also clear up the air, literally, for boaters.

Eliminating CO At Its Source
Work on new engine designs to reduce the CO hazard where it originates are moving ahead at a fast pace, prompted in part by pending new federal environmental regulations.

“I’m pretty confident we’re moving toward an engineering solution,” said John McKnight about the carbon monoxide hazard. He is director of environmental and safety compliance for the National Marine Manufacturers Association. “Before the end of this decade we’ll have greatly reduced the carbon monoxide problem. We just have to prove the technical feasibility of catalytic converters in the marine environment.”

Many boaters don’t realize that marine engines produce more carbon monoxide than cars because boat engines do not have any after-treatment of the exhaust. Automobiles have had catalytic converters for decades to reduce tailpipe emissions under standards set by the Environmental Protection Agency. Only in the last decade has the EPA begun setting standards for marine engine emissions and the job is currently only half finished. Outboard engines are now manufactured under new EPA standards, phased in through 2006, and the next set of regulations will cover gasoline sterndrive and inboard engines.

“The EPA will come out with a major engine rulemaking later this year that will include strategies for CO reduction,” said McKnight.

Meanwhile, the state of California, through its powerful Air Resources Board, is moving toward requiring catalytic converters on marine sterndrives and inboards, ahead of the EPA. Because the state’s air pollution was once one of the nation’s worst, the EPA grants California special waivers to create its own emissions rules, which tend to become the standard for the rest of the nation since manufacturers cannot normally create a product line for just one state.

Catalyst Questions
Generally, a gasoline inboard engine will generate 10,000 ppm of carbon monoxide; if the boat is moving most of it is dispersed into the air. But health experts say 25-50 ppm is hazardous enough to limit exposure. At 200 ppm a person will start to feel sick with a headache, nausea, fatigue or dizziness (often mistaken for seasickness). At 1,200 ppm a person is in immediate danger of dying.

If catalytic converters on cars and trucks have done such a great job of reducing tailpipe emissions, why not on boats? A catalytic converter works by forcing engine exhaust into a honeycomb of pinholes which restricts the molecules and creates more heat so they oxidize. This process is a secondary burning of exhaust which results in carbon dioxide and water.


Under an ongoing joint research program of the marine industry, engine manufacturers, the Coast Guard, EPA and California, catalyst technology has so far only been tested on freshwater sterndrive and inboard engines.

Tests on four powerboats from 19 to 23 feet equipped with two MerCruiser and two Indmar sterndrives and V-drives over 480 hours of operation produced carbon monoxide reductions up to 99% (engine running at idle). Peak levels were 200 ppm.

A follow-on series of tests of catalytic converter-equipped engines in saltwater was to be done this summer, however, cost issues with California have put this plan on hold. The Coast Guard and engine manufacturers are pushing for the test to go forward because there are major safety concerns that haven’t been addressed.

“The bigger issue is what happens with saltwater ingestion. We know salt will corrode and the catalysts can get blocked. It’s like putting a cork in your exhaust system,” said McKnight. “These are all potential concerns that need to be ruled out in saltwater testing.”

The Coast Guard is also very concerned about the safety of catalytic converters in saltwater engines because of the risk of fire and fuel or exhaust leaks. The agency has written to the EPA on the potential safety hazard. However, California currently has a waiver request before the EPA to let them require catalytic converters on marine engines by 2008.

“Our main concern is what saltwater, which is much more corrosive, will do to the exhaust systems. You are creating more heat in a small engine space,” said Phil Cappel, executive director of the Coast Guard’s National Boating Safety Advisory Council and former chief of product recalls. “We have to know if our other regulations need to change, such as type of fuel hoses.”

Even so, Cappel shares the optimism that better engine design might eliminate the carbon monoxide hazard significantly. “We are so far ahead of where we were five years ago,” he said.

A CO-Free Generator
As this issue goes to press, field testing had just wrapped up on a new marine generator reported to run 99% free of carbon monoxide. Two Westerbeke generators were installed on two 70-foot houseboats at Lake Mead, NV, and run on a continuous basis, along with meters to test its effectiveness in a real boating environment in mid-March. A CO-free marine generator would go a long way toward eliminating both cabin and fresh air poisonings from generator exhaust such as those that led to the houseboat recall.

“I would say the initial results look promising,” said Dr. Scott Earnest of National Institute for Occupational Safety and Health (NIOSH) who participated in the Lake Mead test. “This was the first field test and we want to do it again at the end of the boating season to see how well they do after extended use.”

CO sensors were placed in eight locations on the houseboats, inside and out, and Tom Sutherland, vice president of sales and marketing for Westerbeke, said he saw the NIOSH chart after the first day of testing that showed a cold start of the generator at 90 ppm of CO and then it ran at zero to 6 ppm of CO for the rest of the day. “They were pleasantly shocked to see the results,” Sutherland said of the federal observers.

Westerbeke is now selling their Safe-CO™ gasoline generator models in 10 sizes from 2.7 kW to 22.5 kW. Prices are expected to be about 20% higher than standard models. The new product won the 2005 Innovations Award from NMMA, judged by writers from Boating Writers International. Kohler is reportedly also working on a similar generator to reduce CO.

In addition, MerCruiser and Indmar unveiled prototypes of sterndrives with catalytic converters at fall and winter boat shows, but they are still in the research and development phase. An engineer with Mercury said they are moving ahead in anticipation of a 2008 EPA requirement.

“It’s impressive that this much progress has been made,” said Earnest. “Developing engineering controls should make a big difference in preventing poisonings in the future.”

Open Air Danger
In continuing research on all boat CO poisonings, a joint task force of NIOSH, the National Park Service, Coast Guard and Dept. of Interior recently updated known cases and, surprisingly more boaters have perished in incidents on deck than inside cabins. In cases where the location of the victim was known, 51 died in topside poisonings, compared to 31 deaths inside of boats.

Since 1990, researchers have found 113 deaths from carbon monoxide poisoning on boats. A total of 458 people were involved in non-fatal poisonings. Of the non-fatal incidents, 131 of these occurred outside on deck; 270 occurred inside. The Coast Guard suspects that as many as 15% of boating drownings could have been CO poisonings.

Currently, a CO detector is required under industry standards on any boat with a gas engine or generator and enclosed spaces below such as a berth, galley or head or cabins.

Another preventative measure has been warning labels and transom placards, particularly on rental houseboats commonly used by less experienced boaters. California has begun requiring a placard on transoms warning about carbon monoxide and propeller strikes which may also be distributed nationwide by boatbuilders and the Coast Guard. In addition, a handful of states have banned “teak surfing” — where a swimmer hangs onto the swim platform of a moving vessel, right where the engine exhaust is at its most lethal.

For more information on carbon monoxide and ways to protect yourself and your guests, the BoatU.S. Foundation for Boating Safety and Clean Water has a special Web site on carbon monoxide at www.boatus.com/foundation/grants/carbon_monoxide.htm.


— By Elaine Dickinson

©BOATU.S. MAGAZINE 2005



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