Don't remember if I posted this before. It's a good time of year to post it
again.
(may be reproduced for no-charge distribution without permission. other uses
subject to permission via poster's e-mail)

There Really is a Deadly Monster
Aboard Your Boat!


Few children grow up without experiencing a common fear. At some point in
childhood we become afraid that an evil monster is hiding in the closet, or
perhaps under the bed.
In most cases, an understanding adult assuages the terror by making a thorough
search of the closet or sweeping a broom handle through the space between the
mattress and the floor. Patient explanation helps the youngster realize that
the "boogie-man" is nowhere to be seen, heard, or smelled and is simply the
product of an over-active imagination.

Perhaps we learn such lessons too well. Each year in North America, about 2500
people are killed by a deadly boogie-man who actually is present in many
situations. The lethal monster, carbon monoxide, is almost impossible to detect
by sight, sound, or smell. A disproportionate number of such deaths occur on
private pleasure boats.

Carbon monoxide (CO) is a gas that is always produced whenever a carbon-based
fuel is burned. When concentrated amounts are trapped in enclosed spaces and
inhaled by human beings, the gas enters the bloodstream through the lungs and
displaces the oxygen needed for vital body functions. Death can occur very
rapidly under high CO concentrations, or over a prolonged period of time when
lesser amounts of CO are present. Gasoline engines and generators are the worst
CO producing culprits. Diesel powered boats emit lesser amounts of CO, but
merely owning a diesel engine and/or genset is not an absolute assurance
against CO poisoning. Using a propane galley stove rather than running a
generator to operate an electric cooktop doesn't entirely eliminate the
problem, either. Like gas and diesel, propane produces carbon monoxide as it
burns.

Major Causes of Carbon Monoxide Accumulation:

Boating safety experts, such as the Coast Guard, cite leaky exhaust hoses as
the most frequent factor introducing carbon monoxide into the enclosed cabin.
Inboard boats are at greatest risk in this category, as the exhaust hoses often
pass behind lockers and bulkheads of staterooms located between the engine room
and the transom.

CO has been known to claim victims aboard boats with no active engines,
generators, or other sources of combustion. In such circumstances, exhaust gas
from a nearby vessel's engine or generator is brought aboard through open
hatches or portlights.

When a vessel is underway, exhaust gases can accumulate in the cockpit when a
low-pressure area develops behind the superstructure. This phenomenon is often
referred to as the "station wagon effect," and can be much worse when the
cockpit has a hard top and is partially enclosed by canvas.


Danger Signals:

Carbon monoxide may be tasteless, odorless, and colorless but the symptoms of
carbon monoxide poisoning may be more easily detected. Many deaths from CO
poisoning occur when all the occupants of a boat are asleep, or are all
simultaneously effected so that nobody has the presence of mind to detect and
react to the problem.

If there is an exhaust leak aboard, odorless CO won't be the only gas leaking
into the boat. There should never be an "exhaust smell" on a boat with a
properly functioning exhaust system and no "station wagon" effect.

Symptoms of CO poisoning include drowsiness, headache, dizziness, nausea, and
eye irritation. Unfortunately, these symptoms are often misdiagnosed as
"seasickness." Has a crew member or family member not normally susceptible to
seasickness suddenly overcome? Are several people becoming sleepy or sick
simultaneously? If so, CO poisoning should be considered near the top of a
short list of likely causes.

The color of a propane flame can indicate the accumulation of carbon monoxide
in an enclosed cabin area. In a healthy atmosphere, propane burns with a blue
flame. As CO concentrations increase, the flame will become less vigorous and
assume a more yellow appearance.

Listed last but far from least, more boats are fitted with CO detectors every
year. If a detector sounds off, a prudent boater will not simply assume that it
must be a malfunction and cannot be a legitimate warning.


A Moment of Preparation beats a Lifetime of Regret


Boaters can take some basic precautions to minimize the risk of CO poisoning.

Exhaust hoses are not immortal. They should be inspected at least annually, and
replaced at the first indication of wear. Look for water stains that might
indicate pin-hole leaks, as well as obvious burning, abrading, crushing,
unraveling, or loosely fit joints.

Opening a forward hatch will promote an airflow through the boat while
underway, bringing a steady supply of fresh air to the cabin areas and breaking
the "station wagon" vacuum at the transom.

Stay well clear of other vessels when anchoring, particularly if there is very
little wind. Minimize the use of generators and other sources of ignition
during sleeping hours. Be extremely reluctant to operate generators or diesel
heaters when "rafted up."

Never install a portable gasoline generator in an enclosed compartment on a
boat.

If wind driving a following sea is bringing exhaust gas back into the cabin or
cockpit, consider a slight change of course.

Educate all passengers about CO and its effects. The life you save may be your
own, particularly if you are the first party overcome by CO poisoning.

Do not allow swimmers to play near the transom when an engine or generator is
running, and be particularly aware that exhaust gas can accumulate under the
swim platform on many vessels. Never allow anyone to "teak surf" by hanging
onto a swim step while a boat is underway. Water skiers, tubers, or others
being towed by a boat should remain at least twenty feet aft of the exhaust
port.

Install carbon monoxide detectors, and maintain them as required. Detectors are
available in both audible and visual varieties. The audible alarm is the only
hope of warning should a CO situation arise while everybody aboard is sleeping.
Visual detectors consist of a chemical dot that changes color in the presence
of CO, and can be useful as redundant indicators. Some audible alarms might not
be heard over engines, stereos, etc, when underway, and in such a case the
visual alarm would be extremely important.

Do not use charcoal for cooking or heating in the cabin. Remain aware of the
need for ventilation when using galley stoves.

A Small amount of Carbon Monoxide can Spoil the rest of a very short life

Research has shown that trace amounts of CO can have the following effects:


Ratio of CO to Air Effects
100 ppm Headache within 2-3 hours
400 ppm Headache within 1-2 hours, extreme within 2.5 to 3.5 hours.
800 ppm Dizziness, convulsions within 45 minutes. Unconscious within 2
hours
1600 ppm Headache, dizziness, nausea within 20 minutes. Death within 30
minutes
3200 ppm Dizziness, nausea, etc in 5 minutes. Death within 30 minutes
6400 ppm First symptoms within 2 minutes. Death within 15 minutes.

(6400 parts per million is slightly more than one half of one percent
concentration of carbon monoxide to normal atmospheric air)

Be safe, be smart, and don't be a victim. Check your exhaust system, install CO
detectors, and review safety procedures before getting underway