Grady-White Boats ADVANCE 257, Owner'S Manual

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P
ERFORMANCE
4–1
C
HAPTER
4: P
ERFORMANCE
P
ERFORMANCE
F
ACTORS
Maximum performance is dependent on many factors and cannot be guaranteed. These factors
will vary with changing conditions. Some of these factors are listed below. Reference the trouble-
shooting guide on page 65, in
Sportfish, Cruisers, Yachts Owner’s Manual .
E
NGINE
E
FFICIENCY
Assuming your boat is equipped with the correct engine, the engine is properly tuned and the
drive system is in good condition, operation will be most efficient at the RPM stated in the engine
manual. Efficiency will decrease if normal care and maintenance are not performed. If the engine
is neglected, power will drop and speed will decrease. In addition, expensive repairs may become
necessary. Be sure to follow all instructions in the engines’ Operation Manuals.
W
EATHER
C
ONDITIONS
Weather conditions sway engine performance. Barometric pressure and humidity affect horse-
power. A change of weather could amount to a 10% loss in horsepower on some hot days.
L
OAD
D
ISTRIBUTION
A decrease in performance will be noted when gear, equipment, passengers and fuel are
added. This extra load will affect the performance of your boat according to the distribution of the
weight. Another type of extra load that could affect performance is the accumulation of water in
the bilge. Keep the bilge dry to eliminate this type problem.
M
ARINE
G
ROWTH
Maximum performance is only obtained when your hull bottom is clean. Growth on the bot-
tom of the boat will increase resistance and decrease speed. These conditions will also increase
fuel consumption.
P
ROPELLER
The condition of the prop has a major influence on the performance of your boat. The engine
should be equipped with the best size prop for normal conditions. Unusual uses or weight condi-
tions may require special props. A damaged prop can affect your boat's top speed, cause vibra-
tions, create a sudden drop in RPMs or even increase fuel consumption.
C A U T I O N
When replacing propellers, stay within the engine manufacturers maximum and
minimum RPM ranges. This information is covered in your engine Manual. If
your boat does not have a tachometer, consult your dealer for propeller changes.
!