Propeller; Propeller Selection - HONDA marine BF40D Instructions D'utilisation

10. PROPELLER

PROPELLER SELECTION

PITCH
Recommended full throttle engine speed range:
BF40D: 5,000 – 6,000 min –1
BF50D: 5,500 – 6,000 min
–1
Engine speed varies with propeller size and boat
condition.
A propeller must be selected to adjust the maximum
engine speed to the recommended engine speed
range.
Using the wrong propeller can cause motor damage.
The proper propeller will assure powerful
acceleration, top speed, good fuel economy, cruising
comfort, and engine service life.
Propeller Selection Precaution
• Outboard motor must be installed vertically in relation
to boat bottom. Set in moderate trim angle, and adjust
the power trim angle to the lowest setting.
• Set the trim tab, so the boat will run in a straight line.
• Protect the propeller from foreign objects, check
regularly for damage, and/or deformation, and
aquatic plants wrapped around the propeller hub.
• Keep the bottom clean of shells, algae froth and dirt.
These will cause a significant drop in top speed.
• When doing propeller checks, select a calm day
with little waves action.
• Avoid strong winds. Wind speed should be less
than 15 km/h (10 miles/h).
• The boat should carry its average load (crew, load
arrangement, ballast).
Pitch ................Advanced Distance During One Turn (Apparent
Advanced Distance)
Pitch Ratio....... P P: Pitch (mm)
D D: Outer Diameter of Propeller
Slip Ratio.........(Visual Advanced Distance – Measured Distance)
During running; the actually advanced distance is reduced by about
10 – 15% due to propeller display pitch.
PROPELLER DIMENSIONS
(Diameter x Pitch)
Select the correct propeller so that full throttle engine
speed is within the recommended range.
(rpm)
• If the engine speed is under the recommended
(rpm)
speed range, lower the propeller pitch by one size
(1 to 2 inches) or more as needed.
• If the engine speed is over the recommended
speed range, select a propeller with a pitch one
size larger or more as needed.
• If the following conditions exist, acceleration will
improve and outboard motor service life will
increase by lowering the propeller pitch.
– Heavy loads such as crew, load, equipment,
– High temperatures and high humidity conditions;
– When operating at high altitude;
– When boat bottom needs cleaning;
– When area around gear case is obstructed;
To increase motor service life and ensure safe
navigation, do not use full throttle for extended
periods, but run the motor at 70 to 80% of full throttle.
• If full throttle engine speed exceeds the
recommended range, it can cause increased
vibration, noise, reduced boat performance, and
possible engine wear damage.
• If full throttle engine speed is below the
recommended range, it indicates that the engine is
being overloaded.
48
Visual Advanced Distance
water skiing, etc;
x 100