Harken Furling Selector

Top 25 Furling Q & A


How do I select the right furling system for my boat?

Clevis Pin Headstay

The Ordering Furling guide explains how to choose a furling unit and accessories for your boat. You will need to know the clevis pin diameter as well as your headstay length and diameter.

What are the differences between Harken's MKIV and Cruising furlers?
Both are designed for longevity and ease of use, but the MKIV has additional features that make it more suitable for performance cruising and racing.

Double-groove Foil
Aerodynamic foil profile.
Double grooves for faster
hoists, douses, and sail changes.
Single-groove Foil
Round profile
for easy rolling.
Single groove.
Halyard and
Tack Swivels
Independent Swivels
Independent swivels
for improved
sail shape.
Fixed Swivel

Fixed swivel.
Split drum removes for racing.
Fixed drum.

Are all Harken furlers capable of reefing a headsail?
Yes, as long as the furling system has aluminum extrusions covering the headstay.

Changing Sails Can I change sails with my Harken jib reefing and furling system?
Yes, changing headsails is simple. Just attach the head and tack to their shackles, pass the luff tape through the prefeeder and feeder, and hoist. The feeders smooth out wrinkles and minor twists in the sail so you can easily raise sail while at the mast or in the cockpit. Choose the optional snap shackles if you plan to make a lot of sail changes.

How can I reduce heel and get better control with a reefed sail?
Harken's MKIV roller reefing and furling units solve the inefficient shape of reefed sails with independent head and tack swivels. The independent swivels allow the middle to furl first, flattening the sail and reducing heel.

Genoa Trim Angle For the best results, use a sail designed specifically for reefing with your MKIV furler. Reefing sails should be designed to have good shape from about 5 to 40 knots.

Additional sail shape adjustments can be made by increasing or decreasing halyard tension and by changing genoa lead car positions. After reefing, simply move the car forward so the sheet between the car and the clew points to the middle of the luff.

Why do I need more than one jib if I can just reef?
Experienced seamen rarely sail without a heavy-air jib because even the best all-around reefing sails can fail. In a blow, you should change to a reefable heavy-air sail before leaving the harbor. A storm jib is vital for offshore passages because of the possibility of hurricane weather. In light air, having a large, lightweight genoa can make sailing a lot more fun.

What is the proper luff tape for my Harken furler?
Sail Clews Units 00AL, 0, 1, 1.5, 2, 2.5, 3, 3.25, and 3.5 use #6 luff tape. Units 4 and 4.5 can use # 6 or #7 luff tape. #6 luff tape is 0.1875" in diameter (about 5 mm) and #7 luff tape is .218875" (about 6 mm).

Most furling sails are designed with a high clew to give the lower part of the sail a better wrap around the foils, and to improve visibility under the sail. A sail with a moderately low clew has the greatest efficiency and that it will maintain good visibility because the tack of the sail is raised off the deck.

Can I use my racing sails with a Harken furling system?
Removable Drum for RacingYes. Most racers don't use a #1 genoa on the furler because the luff is usually too long and the construction too light. A #2 or smaller genoa should be strong enough to handle reefing and short enough to use with your furling system. Harken MKIV furlers feature an easily removable drum that allows you to use the dual groove extrusions as a twin-foil headstay—this means fast sail changes when you're racing.

Can I use my cruising spinnaker with a Harken furling system?
Yes. Most cruising spinnakers attach to the headstay with a snap shackle. Ask your sailmaker to replace the shackle with one that works with a furled sail—probably one with a padded strap or string of beads to hold the sail near the headstay.

What does it cost to add luff tape to my sail?
Costs vary, but most sailmakers base prices on luff and leech lengths.

What brand of sails should I buy?
Select a sailmaker who offers answers that show an understanding of reefing and furling systems.

What size genoa should I use as my primary reefing sail?
This depends on your boat and your normal sailing conditions. Most boats find a 150 percent genoa ideal. Light air and 125 percent genoas are also common in certain regions. Discuss sail size with your sailmaker.

Can I use my old sails with my new jib reefing and furling system?
Yes. Ask your sailmaker to modify the sails you use regularly, including at least one genoa and one heavy-air sail. If you sail in an area that requires specialty sails like drifters, convert these as well. Sails should be in good condition.

How are sails modified for jib reefing and furling systems?
Your sailmaker will remove the hanks and add a luff tape so the sails slide into the foils. Larger sails may need to be shortened to make room for the halyard swivel. Adding a sun cover to the sails you store furled will protect them from ultraviolet damage.

What should I look for when I purchase a new sail?
Look for a sail designed for a range of wind conditions. The best sails to use with roller reefing and furling units are those built with shaping devices in the luff to improve sail efficiency. Adding a sun cover to the sails you store furled will protect them from ultraviolet damage.

What's the best way to protect my sail from the sun?
Genoa Sail UV-ProtectionProlonged exposure to ultraviolet rays deteriorates most sailcloth, so any sail left rolled on the headstay needs protection. Your sailmaker can add UV-resistant material to the foot and leech panels—this can usually be done without adding a lot of extra weight. Most sailmakers prefer to use fabrics like Acrilan® (the same material used for mainsail covers).

Alternatively, some sailors use a long sock-like bag to cover their furled sail. This design won't add weight to your genoa but you’ll need a spare halyard to hoist it. Be aware these covers can flog in a breeze.

How strong should my reefing jib be?
The sail should be powerful enough to move the boat efficiently in light air and chop, but flat enough to sail reefed in severe conditions. Modern shaping devices allow sailmakers to build sails that work in winds ranging from five to 40 knots. Most sailmakers use foam or rope luff pads. Some use the Aeroluff® system. Ask your sailmaker which shaping device is best for your boat.

Code Zero FurlingCan I use a Code Zero furling for a screecher sail on my trimaran?
The Code Zero furler was designed to handle the massive sail area of upwind spinnakers on ocean racing boats, but it can also be used with screechers. Because the single line driver of the Code Zero furler is fairly large, there is more torque power when rolling up the sail. If a screecher is used in heavier air, rolling up the sail is considerably easier.

If the sail is somewhat oversized, the continuous line can handle any amount of sail without the drum filling up with line. The disadvantage is that because the line is continuous, there are two lines to deal with instead of one.

For cruising sailboats, we have a dedicated screecher furler that works off the same concept as a standard headsail furler. A screecher furler only has one line and the cost is a fraction of a Code Zero.

Can Small Boat furlers be used for reefing the headsail?
No. Small Boat furlers do not have a foil system and cannot be reefed. You should only sail with the headsail completely furled or unfurled.

Can I still use my hank-on jib with a Harken Small Boat furler?
You can use the jib if you replace the hanks with luff tape. You do not need a new jib cut. Most sailmakers can do this for you.

Small Boat FurlingHow are Small Boat furlers attached to the sail and boat?
Headsails used on Harken Small Boat furlers require the installation of a luff wire onto the sail. The luff wire comes out from the luff at the head of the sail and attaches to halyard swivel. The top of the swivel attaches to the halyard. The bottom end of the luff wire attaches to the top pin of the furler’s spool assembly.

Small Boat furling systems can be installed either as an integral part of the headstay or behind the stay as an independent part.

426 Halyard SwivelHow do I fly multiple headsails if I have a 436 furler?
You should install the furler behind your stay. Some boats have a chain plate at the bow with multiple holes. The headstay goes to the forward hole and the lower unit is installed in one of the holes behind it. The 426 halyard swivel has a stainless steel crane that keeps the halyard swivel close to the stay.

Can I store a sail on my Small Boat furler?
Yes, you can store your sail furled on the furler so it’s ready for the next time you use your boat. If you leave the boat with the rig in place and the sail furled for long periods, make sure the sail has adequate protection against UV damage. Your sailmaker can sew protective UV-resistant material along the foot and the leech of the sail. When the sail is furled, the screen will be the only portion of the sail exposed to the sun. Remember to furl the sail so that the sun screen is on the outside.