Exhaust system
22
Exhaust outlet through boat bottom – concept design
Principle sketch, exhaust outlet through bottom
In some installations an exhaust outlet through the bottom of the boat might be the prefered alternative.
In such an installation a full strength pipe (metal, grp,
or similar) must go from the hull up to a level above
the static water line when the boat is moored in order
to avoid needing a shut-off valve.
Incline the pipe slightly backwards and design the
outlet in the bottom to avoid water being pushed up
the pipe if the boat is towed or running with one en-
gine only.
Position the outlet in the bottom in a way so the ex-
haust gases will not create negative turbulance flow-
ing into the propeller or trim tabs, not even when the
boat is turning, as this will affect the performance of
the boat.
A by-pass outlet should be installed from the exhaust
pipe, above the water line, to an outlet above the wa-
ter line to avoid high backpressure when starting the
engine and reduce the low idling pressure pulses to
the hull, which create noise.
Often a riser is needed to obtain the correct distance
(350 mm / 4") to water line (WL), see
Exhaust riser
in chapter
Wet exhaust line.
350 mm
(4")
3
2
4
. Exhaust hose
2. Exhaust pipe
(Full strength pipe)
3. Exhaust outlet
4. By-pass outlet
Summary of Contents for D11 series
Page 1: ...Marine Propulsion Diesel Engines Installation 1 1 D E D5 D16 series ...
Page 2: ......
Page 208: ...206 References to Service Bulletins Group No Date Concerns ...
Page 209: ...207 Notes ...
Page 210: ...208 Notes ...
Page 212: ...7748655 English 11 2007 ...