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MKIV Unit 1 Furler


Model # 8712648 | Mfg # 7411.10 1/2
In stock online.

MKIV Jib Reefing & Furling Systems

Designed for performance racing and cruising sailors, these strong, lightweight, aerodynamic systems are built with longevity, ease of use, and simplicity of installation as vital design components.

Installation is easy: C-shaped open connectors with low-friction plastic isolators slip onto the headstay wire and into the foil without the need to cut your headstay. The foil's twin grooves and smooth feeder allow fast hoists, douses, and sail changes—ideal for club racing. The drum install over the existing turnbuckle and is adaptable to a variety of rigging options. The Harken toggle assembly accepts standard turnbuckles using swage, rod, Norseman or Sta-Lok terminals, or fits directly to a marine eye and the turnbuckle body is accessible for adjustment by raising the drum.

Other outstanding features:

  • Multiple rows of free-rolling Torlon® ball bearings minimize friction for smooth sailing
  • in high-load areas, computer-designed stacked bearing races and large-diameter drums offer smooth reefing and furling.
  • Independent head and tack swivels shape the sail when partially furled
  • Strong foil joints withstand years of torque loading and are easy to assemble
  • Small diameter torque tube with tapered top ensures the furled sail has a smooth, compact shape
  • Deep-saturation Hardkote anodized line guard, torque tube and swivels for strength and durability
  • Removable split drum comes off easily for racing
  • Stainless feeder allows easy hoisting and sail changes
  • Double grooves for racing sail changes
  • Fits #6 luff tapes

The controlling dimensions for sizing Harken furling systems are headstay wire diameter and clevis pin diameter. Measure your boat's headstay length to determine whether a standard package has enough foils to build the unit.

  • Choose Unit 0 for boats 22'–30'
  • Choose Unit 1 for boats 26'–36'
  • Choose Unit 2 for boats 36'–46'

MKIV Unit 1

For boats 28' to 36' and headstay lengths from 45'11" to 52'7".

  • Boat Size: 28'–36' (8.3–11m)
  • Headstay Length: Standard 45'11" (13.99m); Max. 52'11" (16.12m)
  • Headstay: Wire: 1/4", 9/32" (6, 7, 8mm); Rod: -8, 5.72mm, -10, 6.35mm
  • Pin Diameter: 1/2" (12.7mm)
  • Headstay Extrusion: Aluminum aerodynamic Air-Foils
  • Grooves: Double grooves for racing sail changes
  • Drum Material: Hardkote-anodized aluminum; drum cap engineered from super-tough polymer resin
  • Head Swivel Material: Hardkote-anodized aluminum
  • Attachment Method: Swage, Rod, Norseman® or Sta-Lok® terminals required; toggle flips for fork or tang chainplate installation
  • Ball Bearings: Torlon® bearings in high-load areas

MKIV Unit 1 Furler

Boat Length 28 to 36 Feet
Features New England Sta-Set Black Line Included
Stainless Steel Feeder
Grooves Double Grooves for Racing Sail Changes
Headstay Length Standard 45 Feet 11 Inches
Maximum 52 Feet 11 Inches
Pin Diameter 1/2 Inch
Warranty Details Seven Years Limited

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by PowerReviews
Harken MKIV Unit 1 Furler

(based on 1 review)

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Reviewed by 1 customer

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(2 of 2 customers found this review helpful)


Best Furler on the market!

By Baba O'Reilly

from Charleston, SC

Verified Reviewer


  • Dual purpose maximizes boat bucks
  • Ease of Use
  • Easy to remove drum for racing
  • Two sail grooves for sail changes


  • Need to be a prof'l rigger to install

Best Uses

  • Cruising
  • Racing

Comments about Harken MKIV Unit 1 Furler:

This is one tough, flexible furling unit. Had mine installed 5 years ago by prof'l riggers and has worked flawlessly since. It furls the cruising jib nicely, and keeps a good shape when its partially furled. The drum splits and can be removed with a hex key to allow use of full hoist race sails. Comes with an integral sail feeder but you might want to add a traditional feeder. The forestay extrusions are oval shaped for some aerodynamic shape and come with 2 grooves. When it's cruising time, reinstall the drum, raise your furling genoa and enjoy. Highly recommend.

  • Was this a gift?:
  • No

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