How to properly order a Harken MKIV Jib Furler

To order a Harken MKIV jib furler correctly you need four things: the right furler type (MKIV for racing/performance or MKIV Ocean for cruising), the correct unit size (based on boat length, headstay length and clevis-pin diameter), the matching toggle/link-plate assembly, and any extra foil sections your headstay requires. Getting these four choices right the first time means the unit bolts straight to your stay and furls smoothly from day one.

Harken MKIV vs. MKIV Ocean at a glance

What is a Harken MKIV jib furler and how does it work?

A genoa roller furling system furls a sailboat's headsail by rolling the sail around the stay. Modern furlers use a plastic or aluminum foil section that protects the cable or rod stay and the sail while making furling easier. The Harken MKIV is a free-rolling furler that lets racers and cruisers quickly furl and reef from the safety of the cockpit while maintaining great sail shape and optimal speed.

The MKIV Ocean shares the same quality as the racing MKIV but leaves out features cruisers don't need. It is built from hard-coat-anodized, UV-stabilized aluminum and uses multiple rows of Torlon® ball bearings to minimize friction, so pulling the furling line is far less physical. The bearings require no lubrication and the unit runs a single-groove foil for straightforward sail handling.

How do I select the right MKIV unit size?

Once you know the furler type for your sailing style, select the unit size using three factors: typical boat length, headstay length and clevis-pin diameter. The tables below list Harken's part numbers for each size.

Do I need any additional foil sections?

If you cannot remove your headstay to measure it, use the "I" and "J" rig dimensions from your boat to determine the headstay length. If your current headstay is longer than the furler's standard length, order additional foil and a connector. One or two extra foils and connectors may be necessary in some cases. Each extra luff-foil extrusion measures 2.13 m (7 ft).

Which toggle and link plate should I choose?

The furler attaches to the boat at the clevis pin. Select the toggle assembly that suits your setup and choose between short or long link plates - use a short toggle for maximum luff length. The table below lists the toggle and link-plate part numbers by model, unit and clevis-pin size.

*Thread ∅ ⅝-18 LH   **Thread ∅ ¾-16 LH

What lead blocks and accessories should I add?

Harken recommends equipping every furling system with a ratchet lead-block kit. Furling lead blocks maintain tension on the line so the unit furls smoothly and easily. An outboard assembly routes the line outside the stanchions to keep the sidedecks clear, while inboard block assemblies are available for the bow pulpit, for handling two lines, for continuous-line furlers, or for cutter-rigged boats with two furlers.

Harken also offers halyard restrainers, installed on the mast near the top of the foil to hold the line against the mast and prevent halyard wrap when furling, and halyard deflectors, installed on the stay above the foil to keep the jib halyard and any additional halyards from wrapping around the foil. Stanchion-mount bases for Carbo and Classic blocks, prefeeders and snap shackles round out the hardware for fast sail changes.

Frequently asked questions

What is the difference between the Harken MKIV and MKIV Ocean?

The MKIV is built for racers and performance cruisers who want a strong, lightweight, aerodynamic unit, while the MKIV Ocean is engineered for cruisers with hard-coat-anodized aluminum and multiple rows of Torlon® ball bearings for durability and easy line handling.

What information do I need to size a Harken MKIV furler?

You need your typical boat length, your headstay length and your clevis-pin diameter. Match those three figures to the sizing tables to pick the correct unit (Unit 0 through Unit 4).

How do I measure my headstay if I can't take it down?

Use the "I" and "J" rig dimensions from your boat's specifications to estimate the headstay length without removing the stay.

When do I need extra foil sections?

Order additional foil and a connector whenever your headstay is longer than the furler's standard length. Each extra luff-foil extrusion measures 2.13 m (7 ft), and one or two extra sections may be required.

Which toggle gives the longest luff?

Use a short toggle to achieve maximum luff length; long link plates with a toggle are available when you need extra reach at the tack.

Do the Torlon bearings need lubrication?

No. Harken's Torlon® ball bearings require no lubrication, which keeps maintenance simple over the life of the furler.

Shop all Harken Genoa Furlers - MKIV & Ocean →

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