Unit 3 MKIV Racing Headsail Reef & Furling System

Harken's MKIV furlers are designed with features for racing and performance cruising sailors. They are strong, lightweight and aerodynamic, with the performance and qualities Harken is known for – longevity, ease of use, and simplicity of installation.

These free-rolling systems make all the difference in headsail control, allowing racers and cruisers to quickly furl or reef while maintaining great sail shape and optimal speed.
Smoothly and quickly unfurl your headsail instead of having to hoist a large genoa in light air.
Allows you to react quickly to changes in wind or weather. Especially advantageous if short-handed.

The drum installs over your existing forestay and turnbuckle and is adaptable to a variety of rigging options.
The lower toggle assembly accepts standard turnbuckles using swage fittings, rod terminals, or Norseman or Sta-Lok terminals.

Independent upper and lower swivels allow the sail belly to start furling before the head and tack for improved (flatter) partially furled sail shape without reducing sail area when required (and without the need for a foam padded luff).

When used for racing, the sail feeder is quickly removeable with just a single fastener and the halyard swivel is lowered below the feeder; then the feeder is re-installed to allow racing as a simple, non-furling, twin-groove headstay foil, with easy sail changes.
The split drum remove easily for racing – allowing for the longest possible luff.

The MKIV comes in "standard" headstay lengths, but longer headstay lengths (up to a "maximum" length) can be attained with the addition of an extra extrusion and connector kit which can be purchased separately (please call for advice).

• Rotates around rod or wire headstay so the furler bearings don't carry the structural headstay load
• Multiple rows of durable Torlon® ball bearings help minimize friction for smooth furling under load
• Lightweight aluminum halyard swivel reduces weight aloft and features four rows of tough Torlon® bearings to withstand higher jib halyard tensions
• Aerodynamic foil shape reduces drag
• Twin groove sail feeder and double foil grooves allow for fast sail changes
• All MKIV racing foil extrusions are black
• Aluminum drum line guards, torque tube, and swivels are deep-saturation hardcoat-anodized and UV-stabilized for durability
• Drum line guards are polyurethane-coated for wear protection
• Extrusion connectors feature two sets of double fasteners and dual bushings for extra strength and support
• Split drum is easily removed for use with racing sails, providing the longest possible luff length
• Large inner drum spool diameter increases mechanical advantage for powerful reefing and furling
• Easy assembly; this unit is designed for owner installation
• Rod rigging requires purchase of a Harken rod adapter stud which must be cut and coldheaded ("mushroomed") by an authorized rod service center
• Designed for use with 1 x 19 stainless steel rigging stays, only
• 7/16" furling line is NOT included with Unit 4 furlers, and must be purchased separately
• Seven-year limited warranty

Unit 3 MKIV racing furlers are designed for headstay lengths up to 74' 8". For headstays up to 81' 8" an extra foil section and connector kit can be purchased. Please call us at 206-632-4462 for advice.


How does the furling line work?
All headsail reefing furlers are equipped with a single furling line that leads from the furling drum to the cockpit. The sail is unfurled by pulling on the appropriate sheet, causing the line to wind into the furling drum as the sail extends.
To furl the sail back onto the headstay, simply pull on the furling line to reverse the process.


NOTE — Some units are sold with an included toggle – choose the size that matches the clevis pin size at the lower end of your boat's headstay or inner jibstay.
On units sold without the required stem fitting toggle, it must be purchased separately. See Related Products.