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d. The penetration depth of the screw/rod in the propeller body, and therefore the
propeller pitch, can be easily varied by the user by choosing one of the following
two procedures, at will:
• PROCEDURE A:
Before installing the propeller on the boat, at first insert into the two housings
two screws/rods each having great length and then screw them up to abutment.
In this way, the propeller will take two very precise pitches: a high pitch to travel
forward and a small pitch to travel backwards. These pitches will correspond
to those stamped on the two respective screws/rods. In order to change said
pitches, each screw/rod must be unscrewed by rotating it counterclockwise
by a specific angle (i.e., a precise number of grooves), thereby reducing the
respective penetration depths in the propeller body. Therefore, the propeller
forward motion pitch will decrease while the backwards motion pitch will
increases. Each of the two propeller pitches (to travel forward and backwards)
will vary according to the number of grooves between the new locking position
of the screw/rod and the previous abutment position thereof.
If the user wants to know the value of the pitch set on his propeller, he should
remember that the number stamped on the screw/rod (see fig. 5) refers to the
propeller pitch in degrees reached when said screw/rod is completely screwed
up to abutment. Therefore, to satisfy the mentioned curiosity of the user, the
screw/rod has to be screwed while counting the number of grooves it rotates
to come into abutment (and therefore how many degrees the propeller pitch
has changed, remembering that the rotation between a groove and the next
one corresponds to a variation of the pitch of 0.5 degrees). If the screw/rod
is the one intended to adjust the forward motion pitch, the above variation
must be detracted from the value of the pitch stamped on such screw/rod. On
the contrary, in case in which the screw/rod is the one intended to adjust the
backwards motion pitch, the variation must be added.
• PROCEDURE B:
Check that the screw/rod already inserted in its housing had been screwed up
to the abutment. Then remove this first screw/rod (corresponding to the first
pitch) from the propeller body and screw up to abutment, in the same housing,
a second screw/rod having length different from the first one. The new propeller
pitch will be the one stamped on the second screw/rod.
