Carbon Monoxide Poisoning

In the summer of 2000, two boys died from Carbon Monoxide poisoning while swimming off the transom of a houseboat. CO is an invisible, odorless, tasteless gas and a silent killer. The design of this houseboat incorporated a cavity under the swim platform into which the generator exhausted. This design resulted in extremely high levels of CO in this cavity when the houseboat was stationary and the generator was running. The boys suffered their fatal exposure to CO in this cavity. The death of these two boys stimulated a significant amount of media attention and eventually led to the involvement of NIOSH {National Institute for Occupational Safety and Health}. It also precipitated an USCG recall of houseboats with a cavity under the swim platform.

NIOSH acquired medical records for a number of National Park lakes and has compiled a report reflecting CO poisonings and deaths. Because the data indicated a greater risk of CO poisoning on houseboats with gasoline powered generators, NIOSH has been focusing its efforts on this type of vessel. NIOSH has conducted tests to ascertain the effectiveness of several designs intended to reduce the CO exposure risk. ABYC staff has been closely monitoring the investigation that NIOSH has been conducting since the fall of 2000.

The following methods developed for reducing the CO exposure risk have been examined:

Vertical Exhaust System -Proposed as an economically viable alternative, the vertical exhaust system involves relocating the generator exhaust terminus to a point well above the upper-deck of the houseboat. This system utilizes a water/gas separator. The CO laden gasses are separated from the wet exhaust and directed vertically through a pipe extending above the upper-deck of the houseboat. The water is discharged through the hull.

Emission Control Device (ECD) - The ECD is a device installed on the generator set immediately downstream of the exhaust manifold and prior to the water injection point. The device employs an ignition system that effectively burns a significant portion of the remaining unburned fuel and hydrocarbons in the engine's exhaust gasses. Initial tests have indicated significant reduction of CO concentration from 40,000 to 50,000 ppm down to 40 to 50 ppm. The device has demonstrated its effectiveness in propane powered forklift applications, but application to hydrocarbon based fuel burning engines is new.

Engine Shutdown Device -This device is a switch installed at the boarding ladder or rear gate. When the gate is opened or the ladder is deployed, the switch opens the ignition circuit and shuts down the generator, stopping the production of co. This device can also be used to shutdown the propulsion engines. A helmsman override is available to prevent loss of engine control while docking.

More recent developments related to CO involve the death of a teenager participating in an activity known as "Teak Surfing." This activity involves an individual holding on to the swim platform (typically made of teak) of a vessel while it gets under way. As a wake builds the individual lets go of the platform to body surf the wave created by the boat. This dangerously exposes the individual to an atmosphere rich in CO. This death precipitated an investigation by NIOSH and an USGG Safety Alert warning of the dangers associated with "Teak Surfing."

In light of the recent deaths resulting from CO poisoning, ABYC will be assessing the need for modification of ABYC's standards that address CO. The timing of this review is directly related to NIOSH's testing and is contingent upon the availability of NIOSH's report from testing conducted on Lake Mead on June 18- 20,2001.

While it is difficult to estimate what the outcome of the review of ABYC's standards and technical information reports will be, it is feasible to identify several possibilities. Among them is the allowance for the vertical exhaust system, the ECD and/or the automatic shutdown device. This effort is being fast tracked and any necessary modification of the ABYC standards will be published as early as possible.

Re-printed with ABYC permission from Fall 2001 newsletter.