Propellers; Diameter; Pitch; Prop Slip - Four winns 248 Vista Owner's Manual

4. Separate coupling face from transmission output
flange.
5. Using a set of feeler gauges, measure the gap be-
tween the coupling face and the transmission out-
put face, next to each bolt, without rotating the shaft.
6. Subtract the smallest measurement from the larg-
est.
A. If the difference is .004" or less, snug up each
nut and bolt, then tighten each nut to 10 to 15
ft.-lbs of torque, then retighten each nut to 30
to 35 ft.-lbs. of torque.
B. If the difference is greater than .004", adjust
engine and transmission mounts up or down,
sideways and/or fore and aft until the difference
between the highest of the measurements and
lowest is .004" or less. Snug up each nut and
bolt, then tighten each nut to 10 to 15 ft.-lbs of
torque, then retighten each nut to 30 to 35 ft.-
lbs. of torque.
7. Check to be sure that the shaft can be turned with
one hand on the coupling.
8. If the shaft can not be turned with one hand on the
coupling, readjust the engine and transmission
mounts up and down, sideways, and/or fore and aft
until the difference between the highest of the mea-
surements and lowest is .004" or less. Snug up
each nut and bolt, then tightening each nut to 10 to
15 ft.-lbs. of torque, then retightening each nut to
30 to 35 ft.-lbs of torque. Be sure the shaft can be
turned with one hand on the coupling.
9. Repeat this procedure on the other side.
E - 5

PROPELLERS

Knowledge of the propeller is most easily gained through
better understanding of the terminology used to refer to
the aspects of propeller size and performance. It should
be noted the Vista™ inboard models are equipped with
nibral propellers and most stern drives Vista™ models
include stainless steel propellers.
Vista™ Owner's Manual
™
A. Diameter
Diameter is twice the distance from the center of the prop
shaft to the extreme tip of a propeller blade. Increasing or
decreasing propeller size will have a direct bearing on the
RPM's an engine will develop. This is due to the greater
amount of propeller blade surface in contact with the wa-
ter. See Figure E5.
Figure E5: Propeller Pitch & Diameter
B. Pitch
Pitch is a measure of helix angle, or angle of attack, of
the rotating blade. Pitch is easily understood if one imag-
ines the propeller rotating through a semisolid such as
butter or gelatin. The distance the propeller will travel in
one revolution is called "Pitch." Increasing or decreasing
pitch will also have a direct bearing on engine RPM's be-
cause of the greater bite taken by the blade with each
rotation. See Figure E4.
C. Prop Slip
When traveling through water a propeller is unable to get
a complete bite because of the fluidity of water. "Prop
slip" is usually expressed as a percent of the computed
theoretical speed. Twenty-five to thirty-five percent prop
slip is common for a cruiser-type boat operating at cruis-
ing speed.
Section E
Page 5