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Choked Up
Posted: Thursday, August 31, 2017 4:24 PM
Joined: 19/08/2014
Posts: 67

S/Y Stealth was back in the water following a refit that included an entirely new engine, generator, and exhaust system. Following three days of sea trials with the boatyard, the captain and engineer decided they were happy to leave and make their way to the first cruising destination of the season, just over 1,000 miles away. Despite a tight schedule, the refit had gone well and all that remained was the re-wiring of some of the yacht’s safety alarms and re-fitting of the soundproofing; something the engineer could do on the way. A flat calm was forecast for the next three days, perfect to give the new engine a good run and a chance to settle in before the season got started.

Casting off at dawn the following day, S/Y Stealth had the open ocean to herself as the chief engineer adjusted the engine power and set about carefully checking over systems while they were running. Communicating with the deck crew by radio, he requested different levels of power as he went through his checks in the engine room.
Just after noon, the crew gathered in the cockpit for lunch with the port behind them fading into the distance. Missing was the chief engineer, still in the engine room working. The captain called him on his radio, but there was no response. “Must not be able to hear over the engine noise,” the bosun commented. “I’ll go down and get him.” 

Creeping through the narrow access to the engine room, the bosun immediately could see something was wrong as he saw the chief engineer lying unconscious on the floor. Quickly trying to wake him before pressing the emergency alarm button on the bulkhead, the bosun saw no obvious injury; the chief was a notorious fitness fanatic, so what could be wrong?

He called the captain, but instinctively decided to get the engineer out of the engine room. On their way out, the captain noticed a flashing red light on the carbon monoxide sensor and knew immediately what it meant. The chief engineer had been poisoned by silent, deadly carbon monoxide. There must be a leak — from the state of the engine room, it looked like the engineer was in the midst of re-wiring the alarm system. The engine was immediately shut down, all hatches opened, and the engineer was brought on deck and given pure oxygen while the coast guard was called for a medevac.

“The symptoms of carbon monoxide poisoning aren’t always obvious, particularly during low-level exposure,” says the UK National Health Service. “A tension-type headache is the most common symptom. Breathing in high levels can cause more severe symptoms, such as an impaired mental state, intoxication, vertigo, and ataxia. In cases where there are very high levels, death can occur in minutes.”
The cause of the engineer’s poisoning was found to be a leaking exhaust system, hidden far from view at the back of the engine room. The carbon monoxide alarm system’s siren was being re-connected, hence the lack of awareness in the engine room or cockpit.

The UK’s Marine Accident Investigation Branch has seen several instances of carbon monoxide (CO) poisoning in recent years on board yachts. Its official report on the most recent fatal incident explains that sources of carbon monoxide poisoning are multiple in the yacht environment. “CO is a poisonous gas with almost the same density as air. It is a byproduct of combustion appliances fueled by oils, solid fuel, or gas,” states the report. “Fossilfueled cookers, heaters, combustion engines, and even barbecues all have the potential to cause CO poisoning, particularly if they are incorrectly installed, poorly maintained, or used inappropriately.” The report goes on to describe just how lethal the gas is as it’s impossible for crew to detect without sensor equipment or alarms. “CO poisoning occurs by inhalation,” the MAIB reports. “The gas has no smell or taste and for this reason it is sometimes referred to as the ‘silent killer.’ Once inside the respiratory system, CO binds tightly to hemoglobin to form COHb, and this reduces the body’s ability to transport oxygen in the bloodstream.”

The U.S. National Institute for Occupational Safety and Health has clear guidelines for preventing carbon monoxide poisoning and stresses that “prior use of equipment without incident has sometimes given users a false sense of safety; such users have been poisoned on subsequent occasions.”
“Engineers often work alone in the confines of the engine room. To do so with no alarm system operational after an exhaust refit is particularly dangerous due to the increased likelihood of a leak of gases from the system,” says Tim Harrison, a marine engineer specializing in engine and generator refit. “All yachts should have a fully functional carbon monoxide detection and alarm system, ideally one that sounds beyond the engine room, but should the system need to be deactivated, battery powered portable alarms are inexpensive and a sensible piece of kit to have on board.”

Steve D’Antonio of D’Antonio Marine Consulting, Inc. explains that specialist units designed for yachts account for traces of carbon monoxide and only trigger at a level that’s becoming dangerous “using a system called time waited averaging. Units designed for installation on board boats are intended to avoid nuisance alarms caused by momentary exposure to CO. It’s a truism [that] anything that sounds regular false alarms is soon to be ignored, and so, avoiding this scenario is important.”
After being flown to a hospital and receiving oxygen therapy, S/Y Stealth’s chief engineer was lucky to survive. From that point on, he never worked in a confined space without a carbon monoxide alarm and another crewmember checking on him regularly. 

Posted: Friday, October 6, 2017 12:31 PM