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Hey Jude, © Jean Treadwell
HCI006BCC
HCI010BCC
HCI012BCC
HCI017BCC
Single-Acting Integral 
Backstay Adjusters
Harken’s integral hydraulic backstay adjuster provides the power 
to optimize sail shape quickly for racers and adjust mast tension 
for smoother furling for cruisers. The cylinder features a built-in, 
single-acting pump.
Every unit includes a hardcoat-anodized aluminum cylinder and 
pump, valve, and stainless pump handle with two attachment options: 
1) a roll pin, installed as standard, locks the handle 
permanently, 2) the roll pin can be left off and the handle may be 
inserted when needed, but stored separately. Cylinders include a 
clevis pin on both ends. A fiberglass position indicator attached to 
the top clevis pin slides down the cylinder as it’s retracted for 
repeatable tension settings. Standard eye-jaw toggles fit all 
Harken cylinders and are recommended on all installations.
The pressure-release knob turns clockwise to close and pump, 
counterclockwise to release. When closing the pump, the knob 
cannot be over-tightened by hand, preventing damage to the valve. 
Release speed depends on how far open the knob is turned. 
Pressure relief is factory set to prevent crew from over-tensioning 
the backstay. 
Harken integral backstay adjusters come in four sizes to fit boats 
9 - 18 m (30 - 60') with stay diameters of 5 - 10 mm (7/32 - 3/8").
Harken recommends attaching a 
toggle to the cylinder’s bottom clevis to 
accommodate stay movement. Standard 
eye-jaw toggles fit all Harken 
cylinders.
*For pin center length open (PCLO) add stroke length to pin center length closed.     **Rod ends (forks) included in weights.     
‡ Relief valves are preset to limit max tension (pull force) to recommend rigging loads and cylinder design limits. Each cylinder provides a specific max pull force.
Supplied fiberglass position indicator 
provides easy visual reference to 
duplicate desired tension settings.
For replacement position indicator 
assembly, order part number H-85275.
Part
No.
- Size
Max 
wire Ø
Stroke
Pin center length
(closed)*
Weight**
 Gap/pin
Ø
Pull force ‡
Repair Kit
in
mm
in
mm
in
mm
lb
kg
in
mm
lb
kg
 
 -6 
 7/32 
 5.5 
 14.17 
 360 
 30 
 762 
 8.36 
 3.79 
 7/16 
 11.1 
 3770 
 1710 
HYKRCI0610
 
 -10 
 9/32 
 7 
 14.17 
 360 
 30 
 762 
 8.36 
 3.79 
 1/2 
 12.7 
 4710 
 2136 
 
 -12 
 5/16 
 8 
 14.17 
 360 
 30 
 762 
 9.72 
 4.41 
 5/8 
 15.9 
 6710 
 3043 
HYKRCI1217
 
 -17 
 3/8 
 9.5 
 14.17 
 360 
 30 
 762 
 9.72 
 4.41 
 5/8 
 15.9 
 8390 
 3808 

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