New York Safe Boating - 2020 - 25

With the advent of ethanol blended fuels, boaters are finding
one of the unfortunate properties of ethanol is its tendency
to attract and absorb water. Ethanol can become water
saturated when it sits for long periods and the combined
ethanol and water becomes heavier than the gasoline.
In other words, the ethanol separates from the gasoline
and sinks to the bottom of the tank. This is called phase
separation and it's bad news for the engine, which won't
run on the (water-soaked) ethanol solution. In addition, the
separated ethanol is highly corrosive and may damage your
fuel tank. So use your boat frequently during the season so
that gasoline doesn't go stale in the tank and don't leave the
boat's tanks partially filled.

compartment, or if it seems you're using more fuel than you
would expect, get a professional to check. Fuel leaking into
your bilge is an explosion waiting to happen.

Ventilation
Gasoline vapor is heavier than air, so fuel fumes will settle
into the lower compartments and bilges of boats. Unless
there is a flow of air to push those vapors out, the vapors
remain trapped. A spark can ignite the gasoline vapors and
cause a fire or explosion.

Natural Ventilation

If your boat will go unused for long periods over the summer,
or will be laid up for the winter with fuel in its tanks, take
some precautions-especially if the fuel is an ethanol blend.
Add stabilizer to extend the life of the fuel, and top off the

A natural ventilation system moves the air surrounding
the boat through the bilge or area surrounding the engine
compartment. The components of a natural ventilation

tank to 95% full (to allow for expansion) before you store
your boat. Tanks left half full or less are more prone to
phase separation.

system include an intake to pull in the air supply, and an
exhaust to expel it. The natural ventilation system brings
fresh air through intake ducts to the area around the fuel
and engine compartments, which allows fuel vapors and
air to mix. Then the exhaust directs the air/fuel vapor mix
overboard. The boat must be moving for natural ventilation
to be effective. The intake is a cowling or opening located
on the exterior of the boat. It faces forward and is placed
above the normal depth of bilge water. The exhaust is
attached to a hose or duct that extends to the lower third of
the protected space, but it must also be above the normal
accumulation of bilge water. The exhaust must empty

Fuel Tanks
Foamed-in aluminum fuel tanks can crack and may develop
leaks over time. Because it's difficult to access the fuel
tanks on many of today's recreational boats, it's not easy
to detect a fuel tank leak. So be "nosy". Check the engine
compartment frequently for the smell of fuel. Keep track of
how much fuel you're using. If you smell fuel in the engine

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New York Safe Boating - 2020

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