Beta Marine Beta 30, Operator'S Maintenance Manual

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12
EXHAUST SYSTEMS
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We recommend care when designing your exhaust system. The most important aspect is to ensure that water cannot
enter the engine’s combustion chamber from the exhaust system.
EXHAUST BACK PRESSURE
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Exhaust back pressure should be as low as possible; it
is increased by long exhaust length and sharp bends.
Keep exhaust systems to a minimum length and have
gradual bends avoid tight angled elbows. Back pressure
should be measured with the complete exhaust system
connected and the engine running at full speed. The
correct measuring point is before the injection bend (at
the manifold flange).
Engine Exhaust Back Pressure
Beta 10 to Beta 25 Max. 70 mm Hg
Beta 30 to Beta 60 Max. 80 mm Hg
Beta 75 & Beta 90 Max. 90 mm Hg
Beta 90T, Beta 105T & Beta 115T 85 to 115 mm Hg
There must be a propeller clearance between the tip of
the propeller blade and the underside of the hull. This should be a minimum of 10 < 15% of the diameter of
the propeller to reduce ‘tip noise’.
PROPELLER CLEARANCE
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x
10% of Prop Dia.
12 Propeller Clearance