CPT Autopilot Operation Manual
© 2018 CPT AUTOPILOT INC.
VERSION 22
PAGE 19 OF 21
Slowly rotate wheel starboard until it will not turn further: mark the tape TDC.
Slowly rotate wheel port until it will not turn further: make a mark on the tape TDC.
Measure the distance between the two lines: ___" Circumference of Wheel :____"
Divide the circumference of your wheel by 360; the answer is the distance for one degree of wheel play for your
wheel. Poor performance may occur if wheel play is more than 25 degrees. Wheel play in hydraulic systems
can be harder to measure and may only occur under heavier loads or intermittently depending on the cause.
Belt Slips, belt adjustment, Excess Torque
The belt should be snug, but over-tensioning is not needed and will make the clutch hard to operate. Increase
the belt tension if the belt jumps in the cogs under load: unlock the clamp lever, push down on the motor box
and relock the clamp lever. The boat must be balanced to lessen weather-helm and provide consistent steering
(See “Sail Trim”). Check the steering system for binding, bad control cable leads, damage, or lack of
lubrication. Correct as necessary. Make sure wheel pulley is centered on wheel, and that belt is aligned. Make
sure hose-clamps and bracket are tight and have not slipped on pedestal. For pedestal diameters less than 4”,
heavy wheel loads, or reversed pedestal installations: the pedestal bracket should be directly fastened to the
pedestal with screws in addition to hose-clamps. If heavy loads cause the motor to flex the mounting so the
belt slips, a belt tensioner will keep the belt tensioned and absorb shock loads from large rudders.
Clutch Disengages
Motor unit may be tilted so the drive pulley shaft is not parallel to the wheel shaft, and belt tension is
disengaging the clutch. Pulleys must be aligned and parallel when the clutch is engaged. If in doubt or the
wheel is not uniform favor a slight belt slant that will help keep the clutch engaged.
The set-screw recessed into the drive pulley-gear adjusts the friction of the ball bearing detente in the clutch.
Slightly tightening this screw will lock the clutch more securely in position; tightening too much will make the
clutch difficult to disengage. This normally does not need adjustment unless it has worked loose or there has
been extensive wear. Use a small bit of thread locker if the screw has worked loose.
Shear Pin Breakage
Be sure all excess friction is removed from the steering system. Steering linkage with excessive play can
transfer sudden shock loads from the rudder directly to the shear pins. Be sure the wheel pulley is basically
centered on the steering wheel. Vessels with excessive rudder shock loads will benefit from use of a belt
tensioner which acts as a shock-absorber.
If the tip of a broken shear pin is not removed, it may get lodged behind the drive-plate and cause a screeching
sound behind the clutch. Remove the clutch & drive-plate to remove the broken tip.
A worn clutch pulley with excessive hub wear will no longer rotate on center and be wobbly, transferring belt
tension to the shear pins instead of the hub and shortening shear pin life; contact us for a replacement pulley
gear. To prolong the life of the clutch and shear pins when hand steering, loosen tension or remove the belt
from the small pulley, and hang the belt on over the binnacle or wheel shaft. Clean and lubricate clutch on a
regular basis.
CPT /- 10 degrees or more in seas, worse in flat water
Be sure the Deadband is set to the lowest setting. Otherwise this is usually an indication of excess play in the
boat's steering system or some magnetic interference. Excess play at the wheel must be removed. Inspect and
tighten cable systems. Air, foaming and valve delay in hydraulic steering systems must be removed. Try
relocating the control box away from stereo speakers and any metallic equipment that may have a magnetic
field; only 316 stainless fasteners should be used to mount the control box.
