10
Exhaust Water Separator
When an exhaust water separator is used
the muffler outlet and water separator inlet di-
ameters must be the same size.
The water separa-
tor should be installed directly above the muffler to
maintain a vertical lift. The through-hull fitting for the
drain hose should be below the load water line and
must have a sea cock. An EXHAUST WATER SEP-
ARATOR BACKFLOW TEST must be conducted
during the sea trials to determine that there is no
backflow that could flood the engine.
Exhaust Through-Hull Fitting
The exhaust through-hull fitting must be above the
load water line under all anticipated uses and
speeds of the boat. To reduce wave wash-in when a
water separator is used
(Figure 2 or 4), the top of
the water separator must be at least 18 inches
(450 mm)
above the load water line
. When an elbow
is used at the top of the muffler outlet hose, the el-
bow must be at least 12 inches (305 mm) above the
through-hull fitting (Figure 3 or 5).
CAUTION
Backflow can cause major engine
damage if the cylinders become flooded. The
sea trials must verify that there is no backflow
through either the exhaust hull fitting or the wa-
ter separator drain hose fitting.
Other Engine Exhaust Systems
Do not “T” into any other engine exhaust system.
Run the genset exhaust piping all the way to the hull
and terminate it flush with or extended slightly from
the outside of the hull.
CAUTION
Corrosive exhaust vapors can mi-
grate through a shared exhaust system and
cause damage to idle engines. Provide a sepa-
rate exhaust system for each engine.
EXHAUST WATER SEPARATOR
BACKFLOW TEST
Objective:
To determine that there is no backflow
through the exhaust water separator under any op-
erating condition (Figure 2 or 4).
Method:
Conduct this test during the sea trials in
conjunction with the RAW WATER PICKUP TEST.
Prepare by closing the drain hose sea cock and dis-
connecting the hose from the water separator. Con-
duct the test by opening the sea cock while keeping
the hose raised to its fitting on the water separator.
Requirement:
There must not be any back flow
while operating the boat throughout its speed range.
If there is, relocate the through-hull fitting.
Redistribution or publication of this document,
by any means, is strictly prohibited.
