Harken Unit 2 MKIV Ocean Jib Furling System

Harken MKIV Ocean Unit 2 – Part 7512.10

The Harken MKIV Ocean Unit 2 is the 7512.10 furling system for yachts requiring a larger-capacity forestay furler than Unit 1, without moving up to the heavier Unit 3 system. Harken lists Unit 2 for yachts typically around 10.6–14.2 m (35–46 ft), but correct selection should be based on the forestay, chainplate, available headstay length and toggle arrangement rather than yacht length alone.

Unit 2 Headstay and Rod Compatibility

Important: older Harken literature may show slightly different Unit 2 wire-size information. The wire sizes above follow Harken's current Unit 2 installation manual. If you are replacing an older MKIV installation, contact us and we can check the existing forestay and fittings before supply.

Choosing the Correct Unit 2 Toggle

The MKIV Ocean Unit 2 is supplied without the lower toggle. The correct toggle must be chosen to suit the yacht's chainplate and forestay termination.

• 7412.20 5/8 – reversible eye/jaw toggle, 15.9 mm (5/8") clevis pin
• 7312.20 5/8 – jaw/jaw toggle, 15.9 mm (5/8") clevis pin
• 7312.20 3/4 – stud/jaw toggle, 19.1 mm (3/4") clevis pin
• 7312.21 5/8 – long link plate with 15.9 mm (5/8") toggle
• 7312.21 3/4 – long link plate with 19.1 mm (3/4") toggle

Harken advises against drilling the yacht's chainplate or toggle to make an incorrect clevis pin fit. Where clearance or anchor interference is an issue, a suitable toggle or long link plate can be used to raise the drum assembly.

Checks Before Ordering a Harken Unit 2

Before ordering, we recommend confirming:

• forestay wire diameter or rod dash size
• chainplate clevis-pin diameter
• existing lower forestay terminal
• finished headstay length
• available clearance around the bow, anchor and pulpit
• sail luff tape size
• halyard lead and swivel position

These checks are particularly important when replacing another manufacturer's furler or an older Harken installation. Choosing the system from yacht length alone can result in the wrong toggle, forestay compatibility or drum position.

Unit 2 Foil and Sail System

The Unit 2 uses Harken's single-groove foil system with #6 / 5 mm luff tape. The standard foil set uses eight 2.13 m (7 ft) foil sections together with the lower foil section, connectors and bushings required to assemble the extrusion around the forestay.

The installation package also includes the furling drum assembly, halyard swivel, sail feeder, foil connectors and installation hardware. The lower toggle is ordered separately because its type and clevis-pin diameter depend on the yacht.

Unit 2, Unit 1 or Unit 3?

Unit 2 sits between the smaller Unit 1 and larger Unit 3 systems. The deciding factors should be the actual forestay diameter or rod size, clevis pin, headstay length and installation geometry rather than simply choosing by boat length.

See our Harken MKIV Ocean Jib Furling Systems range to compare the available unit sizes.

Need Help Confirming the Correct Furler?

Martin Leaning Masts & Rigging can help identify the correct Harken furler, toggle and forestay arrangement before ordering. Send us your yacht details and existing forestay measurements, or contact us for rigging advice. Video-call support is also available where seeing the existing installation will help.