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Jib Furling Service and Maintenance

In this article:

  • Tips for servicing your jib furler
  • Furler maintenance
  • Inspection checks
  • Troubleshooting guides
  • Replacing your furler
  • Benefits of modern furling systems

    PLEASE NOTE: As of June 2021, Harken is no longer taking orders for the ESP line of cruising furlers. We will continue to provide tech support and inventory a limited number of spare parts and manuals for existing users.

How do I service my jib furler?

Thankfully, modern furling systems are designed to minimize your service and maintenance requirements but the need for performing these tasks hasn't been eliminated altogether. Therefore, you'll need to do some housekeeping to keep your furler working well and your warranty valid. Harken's website provides free online guides that walk you through the maintenance process.

Click here for online furler maintenance guides.

STEP 1: Identify your furler

There's no universal rule for servicing furlers - replacement parts and maintenance requirements are specific for the type of furler you own. To start, you need to identify which jib furler you have.

Click here to view the family identification table online (page 2).

STEP 2: Identify the size of your furler

The MKIV and cruising furlers have the unit size printed on the label and MKIV on the feeder. On older models you must measure the drum diameter (measure across the top of the drum), the clevis pin diameter and the torque tube length (see below image for reference).

STEP 3: Let maintenance begin!

Clean regularly. It's important your furler remains clean and salt free. When giving your boat its regular wash down, clean your furling drum with soap and fresh water while you're at it. In addition, it's a good idea to give your furler a more thorough cleaning twice a year.

For more thorough inspections:

  • Remove the line (noting the direction on spool).
  • Flush the bearings with soap and fresh water.
  • Clean the foils with soap and fresh water.
  • Run a scrap of luff tape up foil groove to clean.

Inspections are essential

Remember all furling parts can loosen, wear, and corrode over time, so it is essential that you periodically inspect the furler components. You don't want to discover there's a problem when you're sailing.

Here's a list of some of the things you should check.


  • Unit for any signs of chafe, wear, or damage.
  • Screws - loose or missing? These should be secured with Loctite® adhesive, so don't turn the screw as you will release the bond. Merely check to make sure they are secure.
  • Foils - make sure they haven't dropped into the drum assembly; check that the torque tube clamp is tight.
  • Wire - look for signs of wear, unraveling, or loosening.
  • Locknuts on leg kit - see if they're still there and haven't come loose.
  • Lower toggles - check for signs of wear, cracks, and corrosion.
  • Cotter pin at lower toggle - make sure it's securely splayed.

My furler isn't working properly, how do I identify the problem?

OK, so you've done your regular furler service and maintenance checks, but it's still not operating as it should. If this is the case, now's the time to do some problem solving.

Below are some common furling problems, their causes, and how you can deal with them. If you're having a problem with your furler, use this guide to establish how to overcome it. 


Sail will not furl or unfurl

Probable cause Solution
Jib halyard is wrapping around the headstay because halyard swivel is too low. A wire pendant may be needed at head of sail to raise halyard swivel to proper height. Use a halyard deflector.
Jib halyard is too tight. Ease jib halyard.
Spare halyard is wrapping in sail as it furls. Secure spare halyards away from furling headstay by flipping them behind spreaders. Use a halyard deflector.
Salt or dirt in bearings. Flush bearings with fresh water.
Furling line tangled in drum. Overrides are best prevented by using a 7402 ratchet block as the last furling line lead to maintain proper drag on line while unfurling.
Stop knot catching. Make sure knot is a single overhand and is pushed up inside spool.
Sail full of wind. Luff completely before furling or reefing.
Sail flogging too much. Release a short length of sheet, pull some furling line and repeat.
Foil out of drum assembly. Reinstall foil in drum assembly and tighten adjuster clamp screws into holes.
No wraps of furling line on spool. Remove sheets from furled sail. Rotate spool to wrap correct amount of line.
Line led through ratchet block backwards. Rerun the line.
Halyard swivel installed upside down. Remount swivel correctly.


Sail will not furl completely

Probable Cause Solution
Insufficient furling line on drum. Remove sheets. Rotate stay, wrapping as much furling line on drum as possible.
Too much line on drum. Adjust amount of line on drum or change position of forward lead block to allow line to roll evenly on drum.
Spare halyard catching in sail as it furls. Move halyards away from furling headsail.


Headstay rotates in jerks or elliptically

Probable cause Solution
Insufficient tension on headstay. Tighten headstay and/or backstay to eliminate sag in headstay.

Sail does not stay furled

Probable cause Solution
Sail not furled tightly on stay. Maintain drag on sheets while furling.
Furling line not secure.

Secure furling line.


Sail will not go up

Probable cause Solution
Luff tape will not go into groove. Check luff tape for fraying and check size is correct.
Sail catching at feeder. Have someone guide sail into feeder. Purchase prefeeder part no. 947.
Dirt in groove. Clean thoroughly.


Sail will not raise completely or luff will not tension

Probable cause Solution
Halyard swivel is hitting end stop or trim cap screws. Luff of sail is too long and must be recut. Consult sailmaker.
Angle between halyard and mast is too sharp and halyard is pulling too much to the rear. Luff of sail may be too long. Consult sailmaker.


Sail will not come down

Probable cause Solution
Halyard is wrapping on headstay. Angle between headstay and halyard is too shallow and must be optimised. Consider adding a halyard deflector.


Sun cover rolls up inside of sail

Probable cause Solution
Furling line is wrapped on spool in wrong direction. Unfurl sail and lower it. Disconnect from furler. Note direction of line wrap on spool. Pull line from spool and rewind in opposite direction. Connect sail and hoist. See commissioning section of manual.


Line is wearing on plastic drum assembly

Probable cause Solution
Line is not lead through guide posts. Lead line into drum between guide posts.


Replacing your furler

Which furler is right for me?
Sometimes servicing isn't enough and it's simply time for a replacement. So you've decided it's time for a new furling system, but you're not sure where to begin? Before ordering, you must first consider your boat's size and the type of sailing you do. Harken has two main types: the MKIV for racers and the MKIV Ocean for cruisers.

Foils Aerodynamic foil profile. Double grooves for faster hoists, douses and sail changes. Single groove, round profile for easy rolling.

Halyard & tack swivels Independent swivels for improved sail shape Fixed swivel
Drum Split drum removes for racing One-piece, fixed, drum, spool, and guard

What are the benefits of modern furlers?

Good visibility

Genoas are generally cut close to the deck, which obscures visibility ahead and to leeward. As many of us sail within a few miles of a harbor, visibility is important for safety and peace of mind. Instead of increasing visibility by cutting your clew high, and permanently reducing your sail area, you can simply reef the genoa when near a harbor, while sailing at night or approaching an area with navigational hazards.

Speed control

Being able to reef the genoa enables you too quickly and easily depower the sail to meet variable shifts in weather.

Full-power headsails

If you don't have the ability to reef, you may be tempted to choose a smaller headsail as the primary genoa. With the ability to furl, you're able to maximize the size of your genoa and simply reef to the prevailing conditions.

Sail more and motor less

Furling systems can make it easier to take advantage of light wind conditions. On yachts where you need to run the genoa up every time you make a headsail change, it can become tiresome for the crew during a cruise. Furling systems enable the helm to set the sail with minimal crew input, making lighter work of sail planning and adjustments.

Less crew needed

Furlers allow you to reef or stow the genoa from the safety of the cockpit, removing the need to drag sails onto the foredeck. This makes it easier to sail shorthanded or use your normal crew to sail a larger boat.

Got a question?

For more information on furling systems, maintenance, troubleshooting, replacements, and/ or other hardware questions, feel free to contact Harken Technical Support via the details below:
technicalservice@harken.com | 262-691-3320

Hopefully this handy guide will help you solve problems yourself, but if you're still stuck, or not quite sure, feel free to Technical Support a call and we can work our way through it together.

technicalservice@harken.com | 262-691-3320

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