2.2 DRIVE SYSTEM
The following notes describe the installation of
both the rotary, linear and hydraulic drive units.
2.2.1 ROTARY DRIVE UNIT
The rotary drive unit is coupled to the steering
mechanism by a simple chain drive. Most steering
gear manufacturers supply special autopilot drive
attachments and many include this facility as
standard. Figs. 15 and 17 show the
recommended rudder
to
times for both planing and displacement
vessels up to 20m (60’)
Figs. 16 and 18
enable the optimum chain reduction radio to be
selected for both planing and displacement
vessels. It is first necessary to determine the
number of turns of the driven sprocket when the
rudder is driven from
to hardover.
Example:
A
(40’)
displacement vessel requiring
two turns of the driven sprocket to drive the
rudder from
to
will require a
chain reduction ratio of approximately
(as
indicated by the dotted line on the chart).
NPE 1:
ROTARY DRIVE CHAIN
REDUCTION RATIOS
Displacement Craft
TYPE 1:
TIME RECOMMENDATIONS
4 0
Fig. 15
METRES
10 I
11 I
12 I
13 I
14 1
FEET
I
I
I
I
I
25
3 0
35
4 0
45
Planing Craft
8
1 0
11
F E E T
I
I
I
2 5
3 0
3 5
4 0
45
LO A
