Four winns 358 VISTA, Owner'S Manual

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Owner’s Manual Page 31 Boating Safety - Section B
Exhaust Fumes!
Hull exhaust from your boat can cause
excessive accumulation of poisonous carbon
monoxide gas within cockpit areas when using
protective weather coverings (while underway
or while stationary). Provide adequate
ventilation when the canvas top, side curtains
and/or back (aft) curtains are in their closed
protective positions.
4. Opening and closing ports, hatches, doors, and
windows may raise or lower CO levels on board a
boat. When airflow is moving forward inside the boat,
CO may be entering the boat. See Figures B-11
and B-12.
Figure B-11: Desired air flow through the boat.
Figure B-12: The effect of canvas configurations.
5. Operating a boat at slow speeds with a following
wind should be avoided. Consider changing
direction, adjusting speed, or both.
See Figures B-13.
Figure B-13: Operating at Slow Speed
with Following Wind
K. Backdrafting (Station Wagon Effect)
Backdrafting or the “station wagon effect” is caused
by air movement over or around a boat creating a low
pressure area or suction area around the stern that
can increase CO level on the boat. Backdrafting can
be affected by relative wind direction , boat speed,
and boat trim angle. See Figure B-9 Backdrafting -
Airflows Over Boat and Behind Transom”.
Under certain speed and operating conditions the low
pressure area may form in other regions and permit
carbon monoxide to enter the hull through openings
that are not on the back of the boat. Boat factors
which may affect CO concentration:
Figure B-9: Backdrafting - Air flows over boat
and behind transom.
1. Intentional or unintentional excessive trim angle
causing high bow angle. See Figure B-10.
2. Excessive or unequally distributed weight.
Figure B-10: Inefficient trim angles.
3. C an vas C onfi gur at i ons - Un der var i ous c on di t i o-
ns, adding or r emov ing canvas may raise or lower CO
l evels. See Fi gures B-9, B-10 & B-12