fountain mercury Express Cruiser 2005, Operation, Maintenance & Warranty Manual

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34
Hull Technology
IMPORTANT TERMINOLOGY
NEGATIVE TRIM
NEGATIVE TRIM
NEUTRAL TRIM
NEUTRAL TRIM
POSITIVE TRIM
POSITIVE TRIM
NEGATIVE TRIM
NEGATIVE TRIM
NEUTRAL TRIM
NEUTRAL TRIM
POSITIVE TRIM
POSITIVE TRIM
Thrust Angle
Negative Trim
CG
Thrust Angle
Negative Trim
CG
Thrust Angle
Negative Trim
CG
Neutral Trim
Thrust Angle
CG
Neutral Trim
Thrust Angle
CG
Neutral Trim
Thrust Angle
CG
Positive Trim
CG
Thrust Angle
Positive Trim
CG
Thrust Angle
Positive Trim
CG
Thrust Angle
TABS OR DRIVES
TRAILING EDGE
BELOW THEORETICAL
RUNNING SURFACE
TRANSOM LIFT –
BOW DOWN
TABS OR DRIVES IN-
LINE WITH THE
THEORETICAL RUN-
NING SURFACE
NO LIFT
TABS OR DRIVES
TRAILING EDGE
ABOVE THEORETICAL
RUNNING SURFACE
BOW LIFT –
TRANSOM DOWN
KEY TECHNOLOGY POINTS
STEPS CHANGE THE ANGLE OF ATTACK, CHANGING PERCEIVED
NEUTRAL TRIM SETTINGS.
STEPS CONTROL PRESSURE.
STEPS ALLOW LOWER DRIVE ANGLES WHICH FOCUS 100% OF THE
THRUST AT PUSHING THE BOAT, RATHER THAN USING THRUST TO
CHANGE THE ANGLE OF ATTACK.
WATER PRESSURE MOVES FORWARD ALONG THE HULL, NOT
BACKWARD. THINK OF STEPS AS A HORIZONTAL STRAKE.
A NEGATIVE TRIM SETTING UPSETS THE PRESSURE ON THE HULL
CREATING A POTENTIALLY UNSTABLE SITUATION AT HIGHER SPEEDS.
THE PAD CREATES A STABLE PLATFORM FOR THE BOAT TO RIDE ON AT
SPEED, AND ACTS AS A WIDE STRAKE.
A NOTCH ALLOWS FOR HIGHER DRIVE PLACEMENT AND IMPROVED
PROPELLER EFFICIENCY FOR EXCEPTIONAL HIGH AND LOW SPEED
PERFORMANCE.