Harken Underdeck Furling Unit


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Harken Underdeck Furling System MKIV

Harken’s MKIV Underdeck Furling is the perfect solution for performance racers and cruisers who want an aerodynamic system with a minimal amount of equipment above deck. The drum is located beneath the deck, lowering the tack height for maximized sail area.

Easy Reefing and Furling:
Ball bearings between the center hub and deck bearing provide low-friction furling.

Durable Materials and Construction:
Size 1 and larger: Aluminum line guard, torque tube, and swivels are deep-saturation hardcoat-anodized for no-fade UV stabilization and durability. The hardcoatanodized line guard is urethane-coated for additional corrosion protection.

The threaded height adjuster uses dissimilar metals (stainless steel and bronze) to prevent galling. Size 0: A one-piece integrated deck bearing and line guard provides durability and corrosion resistance.

Easy to Maintain:
The furler can be flushed clean with detergent water like traditional furling.

The through-deck bearing minimizes water seepage into the underdeck compartment.

1. Torque Tube Houses Full-Length Turnbuckle - The torque tube houses a full-length turnbuckle for optimal mast rake and tension adjustment.
2. Articulating Torque Tube Attachment - A torque tube universal joint on Units 1, 2, and 3 provides a high-strength universal connection to allow ample headstay sag when sailing downwind. The Unit 0 features an articulating ball joint, eliminating the universal joint and toggle to reduce weight and to simplify maintenance.
3. Belowdeck Drum Fits Narrow Bows - The small outside drum diameter lets unit fit inside narrow bows.
4. Installation Options - Units 1 and larger have self-locking threaded height adjusters for a correct fit between the chainplate and deck. The Unit 0 does not need a height adjuster. The furler and headstay are independent of each other, allowing flexible installation options.