Harken MKIV Unit 0 Furling System w/o Toggle Assembly

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Harken MKIV furling systems are strong, lightweight and aerodynamic, with the performance and features Harken® is known for. Longevity, ease of use and simplicity of installation are crucial components of the design. These free-rolling furlers make all the difference in headsail control by allowing racers and cruisers to quickly furl and reef from the safety of the cockpit, while maintaining great sail shape and optimal speed. 

Halyard Swivel Turns Freely Strong, lightweight halyard swivel reduces windage and weight aloft to minimize pitching and heeling. Stacked bearing races evenly distribute radial and thrust loads to ball bearings; foils turn freely under halyard loads. Independent halyard and tack swivels furl sail center before head and tack for improved sail shape and upwind pointing. 

Drum Installs Over Existing Turnbuckle Units are adaptable to a variety of rigging options for easy installation. Harken toggle assembly accepts standard turnbuckle using swage, rod, Norseman® or Sta-Lok® terminals. Toggle flips for fork or tang chainplate installation. A single stainless steel clevis pin provides access to the turnbuckle for adjustment. 

Stainless Steel Feeder Stainless steel feeder allows fast singlehanded hoist and quick sail changes. 

Removable Split Drum Line guard and spool come off easily for racing. 

Part Number: 7410.10


  Imperial Metric
Wire 1/8", 5/32", 3/16" 3, 4, 5 mm
Rod -4 4.37 mm
Clevis Pin 1/4", 5/16", 3/8", 7/16" 6, 8, 9.5, 11 mm
Standard Headstay Length 38' 7" 11.77 m
Max Headstay Length 45' 7" 13.9 m


  Imperial Metric Harken Furlers
A 3 3/4" 96 mm
B 5 7/8" 150 mm  
C Max 9 7/8" 250 mm  
D 1 7/8" 47 mm  
E Max 41" 1041 mm  
E Min 39 1/2" 1003 mm  
F Max 8 3/8" 213 mm  
F Min 8 1/4" 209 mm  
G Max 7 5/16" 186 mm  
G Min 7 5/16" 183 mm  
H 5 1/2" 140 mm  
I 2 5/8" 66 mm  
J Max 2 5/16" 59 mm  
J Min 2 3/16" 56 mm

Need help to design your Harken system - take a look here for the Harken System Guides and Drawings
Or perhaps you need some other information (load calculators, block selectors, service instructions or manuals)?   Take a look here for all the official Harken Support Information