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© Medora Media / Doug Wake
Harken’s MKIV Underdeck Jib Reefing & Furling line is the 
perfect solution for sailors who want an aerodynamic system 
with a minimal amount of equipment above deck. The under-
deck furler provides a low-friction, clean layout solution that mini-
mizes windage, while uncluttering the bow for easy anchor 
access. Offered in four sizes for boats from 6.7 – 18.3 m (22' – 60').
Low-friction efficiency for easy furling 
and reefing
• Ball bearings between center hub and deck bearing, 
 and main shaft reduce friction; drum and halyard 
 swivel turn freely under load.
• Foils rotate around headstay so headstay load is 
 isolated from the unit for easy furling.
Stand up to sun, salt, and time
• Units 1, 2, 3: Aluminum line guard, torque tube, 
 and swivels hardcoat-anodized, UV-stabilized for 
 durability. Line guard is polyurethane-coated for 
 additional corrosion protection. Threaded height 
 adjuster uses dissimilar metals (stainless steel and 
 bronze) to prevent galling. 
• Unit 0: One-piece integrated aluminum deck bearing 
 and line guard hardcoat-anodized for durability and 
 corrosion resistance.
• Aerodynamic, clear-anodized aluminum Air foils 
 handle extreme reefing loads.
• Triple-interlock foil joints withstand years of torque 
 loading: foil connector’s geometric shape interlocks 
 with foil; secures with syringe-injected adhesive; 
 screws provide final lock. 
MKIV UNDERDECK JIB REEFING & FURLING
DO NOT use Harken equipment for human suspension unless product is specifically certified and labeled for such use.
STA-LOK is a registered trademark of STA-LOK Terminals.
Foil joints
Unit 0
Unit 1
Unit 2
Unit 3

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