How to Choose Furlers for Reaching Sails on Cruising Sailboats

Reaching Sail Furler Options for Cruising Sailboats

Sails built for the sole purpose of reaching, or sailing off the wind, offer a range of powered up sailing for cruisers. Paired with a furler, these sails are easy to handle and maximize your boat speed (especially in light air).

The two types of furlers for cruising reaching sails are:

  • Bottom up furlers for straight luffed Cruising Code 0 sails
  • Top down furlers for free flying a-symmetrical spinnakers


Advantages of Furling Reaching Sails

Furling reaching sails allow you to store sails rolled on their flexible furlers below decks.  They can be easily and quickly rigged on deck, have continuous furling drums/lines for trouble-free furling and unfurling once they are hoisted on the halyard, and they afford easy sail handling for a crew of two or a single handed crew with an autohelm.

Where do Reaching Sails and Furlers Fit into the Sail Inventory?

We get this question often at APS from sailors who are confused by what furler works with which type of reaching sail.  In this post, we will broadly review the types of sails available for cruising, including sails you may already have on board like a genoa and symmetrical spinnaker.  We will classify reaching sails as cruising code zero and asymmetrical spinnakers.  Know that each sailmaker will have different ‘in-house’ names for reaching cruising sails and that they can all be designed to be optimal performers for a specific range of wind angles that you and your sailmaker would discuss and agree on.  We will then discuss the two types of furling options for reaching sails and their advantages when cruising, especially when sailing with a crew of one or two.

optimal apparent wind angles by sail type

As you can see in the above diagram, different sails perform better within different ranges of wind angles. First, we will discuss the headsail and the spinnakers often found on cruising sailboats, and their wind angle ranges.

Roller Furling Headsails

Headsails on roller furlers offer upwind performance, ease of handling, the safety of furling from the cockpit, and space-saving sail storage on the furler.

Most new cruising boats over 30’ come with a ridged forestay furling system and a 130% genoa as standard equipment.  This combination is ideal for sailing close hauled and offers respectable performance on a tight reach.  Head off the wind some more and the sail is pretty small and flat for a beam reach (90 degrees apparent wind angle). This is especially true in lighter air (under 10 knots).  Any angle deeper than a beam reach in a medium-light air and you may as well furl the sail because the mainsail begins to blanket it while its flat and relatively small size does not perform well.  On light air days, the dreaded ‘iron genny’, motor sailing, typically comes in to play when reaching which is not what you went sailing to do.

Symmetrical Spinnakers

What about the symmetrical spinnaker you may already have onboard?  For true downwind running, the symmetrical spinnaker is a classic way of sailing your boat when your apparent wind angle is in the 110 – 180 degrees range. Although, this includes using a spinnaker pole and sheets and guys, plus the challenges of jibing the sail and pole.  Not ideal for a shorthanded crew.  Using a spinnaker sock helps to better control the douse, but they are not as easy to use or as space saving as a furled sail.

For dead downwind sailing the symmetrical spinnaker is your best and most stable sail choice, but for reaching angles there are easier and more efficient options to get you there faster. Enter reaching sails.

Reaching Sails & Furlers

For all the reaching points where a furling 130% genoa and the symmetrical spinnaker are not efficient in light air, there is the temptation to turn on the engine when the wind drops.  But don’t start the engine.  Enter reaching sails. These are the sails and furling options which make sail changes easy for a crew of one or two and keeps your boat quietly moving.

There are two types of sail furlers that are matched to distinctively different types of sails.  First, we will discuss the sails.

Cruising Code Zero

code zero sail

Code Zero Sail

For close reaching a cruising Code Zero sail offers outstanding power to drive the boat in medium to light air.  These are large genoa-like sails made with a straight luff and a mid-girth that is less than 75% of the foot length.  This type of sail will typically be designed within a range for sailing 60 – 130 degrees of apparent wind, and you would target a smaller range with your sailmaker based on your needs and existing sail inventory.  These sails excel at close reaching, with performance falling off as the reaching angle increases, but all the while generating substantially more power than the 130% genoa.  They also will generally have a higher cut clew that allows for more flexibility in sheeting position and angle.  The key factor in terms of furlers choices is that it is an upwind sail with a straight luff.

Image courtesy of Selden

Asymmetrical Spinnakers

asymmetrical spinnaker

Asymmetrical Spinnaker

For broader sailing angles of 90 – 150 degrees you will want to switch to an a-symmetrical spinnaker which will be bigger, wider (especially at the top) and much deeper than a Code Zero.  The luff is curved and is designed to project more sail area forward.  The power and ease of trimming an a-symmetrical may keep your engine quiet in all but a drifter-wind-day.  The key factor in terms of furlers is that the sail had a positive curve in the luff.

Image courtesy of Selden



Bottom Up (Code Zero) Furlers


code zero furlers

Code Zero Furlers Brands from left to right: ProFurl, Selden, Harken, Ronstan, Karver

Bottom up (or code zero) furlers are specifically designed for Code Zero sails. The sail has a torsion cable (anti twist) sewn directly into the straight luff of the sail with thimbles at either end.  The thimble tack eye connects directly to the furling drum at deck level and the thimble head eye to the top swivel.  In order to keep the luff as straight as possible when sailing upwind, the halyard must be extremely tight and highly loaded.  To achieve this without overloading the mast, a 2:1 halyard is recommended.  This also requires the torsion cable in the luff to be extremely strong and low stretch.  The furling drum will be attached to a fixed or retractable bowsprit that is reinforced to handle the halyard tension loads.


To deploy the code zero: The furling drum is attached to the sprit and the continuous furling line is lead aft.  The furled sail is hoisted, the furling line is released, begin sheeting in, and the sail immediately rolls out and is sheeted the rest of the way in.

To furl the code zero: The sheet is eased and the continuous furling line is pulled which rotates the furling drum.  This rotation is immediately transferred to the torsion cable in the sail.  As the bottom of the torsion cables rotates, this travels up the length of the cable and the middle and top, and immediately begin to also rotate and furl the sail – furling the sail from the bottom up.

parts of code zero furler

Image courtesy of Ronstan

The key to these sail furlers working effectively is that the sail has a straight luff, has a mid-girth <75% of the foot length, has a torsion cable is permanently sewn into the luff of the sail, and that torsion cable is highly tensioned by the halyard when in use.

Top Down Furlers

top down furlers

Top Down Furlers Brands from left to right: Selden, Ronstan, Harken, ProFurl, Karver

For asymmetrical spinnakers, there is the top down sail furler. Here we are dealing with a top swivel and continuous furling drum, plus a torsion cable. Asymmetrical spinnakers, unlike code zeros, are free flying and the torsion cable is not sewn into the sail but is part of the furler system.

The tack of the sail is attached to a swivel on the furling drum so that as the drum is rotated/furled, the sail does not furl at the tack. The torsion cable runs from the top swivel directly to the drum. The head of the sail is attached to the swivel at the same point that the torsion cable is attached.


To deploy the asymmetrical spinnaker: Follow the same steps as a code zero sail. The furling drum is attached to the sprit and the continuous furling line is lead aft.  The furled sail is hoisted, the furling line is released, begin sheeting in, and the sail immediately rolls out and is sheeted the rest of the way in.

To furl the sail: Bring the boat heading to a broad reach.  The continuous furling line is pulled as the sheet is let out just shy of allowing the sail to flog, the drum rotates, the torsion cable rotates, and the top of the sail begins to furl around the torsion cable; while the tack does not due to the swivel it is attached to on the top of the drum.  As the sail continues to be furled, this action will work its way down the sail to the tack, and eventually, the whole sail is quickly furled around the torsion cable.

Furling and unfurling of the sail are all done from the safety of the cockpit, with a crew of two, or one with an autohelm.

The furling drum is in some cases identical to the code zero version, other than a ball bear swivel has been added to the top of the drum to attach the tack of the spinnaker.  The top swivel will usually be the same for both bottom up and top down furlers.

Many of the furler drums can be used for both bottom up and top down furling, as the fitting (swiveling/non-swiveling) on the top of the drum can be quickly changed out.  This allows you to use one furler for both code zero sails and asymmetrical spinnakers.  If you have questions about this, just give our team at APS a call.

Top down furling units usually include the torsion line or cable and will need to be cut and fitted to length.  Finishing the ends is done with mechanical fittings or sleeves allowing boat owners to do it themselves.  For those furlers that do not include the torsion cable/line, APS can supply you with either a Harken cable kit or a Ronstan line kit, which both come with cable/line clamps so you can make them up yourself.

parts of a top down furler

Image courtesy of Ronstan

FAQs and Tips for Top Down Furlers
  • Old sails can be used on a new furler, but check with your sailmaker to be sure the existing cut of the sail will successfully furl.
  • Soft webbing loops on the head of the sail rather than a stainless steel ring will help the head of the sail to start furling more easily.
  • If your furler has an adjustable tack swivel (the swivel can slide up and down the torsion line) with a downhaul, be sure it is properly tensioned before furling and unfurling the sail.
  • A stiff head patch may interfere with furling at the beginning.  As the head patch softens, the sail will begin furling more easily.
  • If you have an option to use a larger diameter torsion line/cable, do it. The thicker this is, the better it will translate the rotation of the drum through its entire length, and the better your sail will furl on the slightly larger line circumference.
  • Be sure to only use thimbles that are from the manufacture of your furler to ensure a proper fit. Any movement of an improperly sized thimble can lead to deformation of the aluminum thimble over time.
  • Ensure your torsion cable/line is the exact length you need for your sail and rig. Follow the manufactures instructions carefully, as they are all different.  Doing the initial set up correctly will pay big dividends.
  • Because the twist of the furling drum needs to be transferred from the bottom drum to the top swivel, high halyard tension is critical to ensure the torsion line is effective in accomplishing this. Torsion cables, like Harken’s, require less halyard tension.
  • When furling, sail the boat down to a broad reach without letting the sail collapse, initially give the sheet a big east which will unload the sail, maintaining a slight tension on the sheet as you furl the sail. Practicing and mastering this smooth maneuver is key to trouble-free furling.  Single-handed sailors (with an autohelm) may struggle initially but will master it with just a bit of practice.
  • Avoid furling the sail if it is luffing excessively.
  • Having the torsion line tight is critical. If the torsion line is not appropriately tight it may not always translate the rotation of the drum to the head of the spinnaker.  If you keep rotating the torsion line without the top spinning/furling, the torsion line stores this energy.  Now if the furling line is allowed to run backward freely, the line will backspin the torsion line and furling drum.  The bottom swivel where the tack is attached can’t keep up and begins to swivel and the foot of the sail now partially furls in the opposite direction around the line.  This is called “back twist” and if it occurs, you will have the sail partially furled in two directions – top and bottom.  When “back twist” happens, and it will, everyone wants to pull hard on the spin sheet to get the wrap out.  All that does is compound the issue and make it harder to untwist.  We recommend pulling the furling line in the same direction as the sail was originally furled.  Look up and if the top of the sail is wrapped clockwise pull the right side furling line to start re-furling the sail the same way.   Once the bottom is flying free from the lower section of the cable you can then either continue to furl the sail or pull the spin sheet to unfurl the sail.   If this is not successful, the sail would have to be lowered to the deck unfurled and sorted.  Not fun.
  • Always watch that the top of the sail is rotating and furling as you pull on the continuous furling line.  If it stops, carefully, and slowly ease the furling line back out.  If the torsion line is tight enough, the sail is not being sheeted too much, and there is nothing caught at the head of the sail, begin furling again.
When a Top Down Furler is Not Appropriate

If you are dealing with a full-size asymmetrical sail for broad reaching, with mid girths approaching 100% of the foot length, with a deep cut, top down furlers may not be a good option, as the sail may not furl completely.  Problems begin with sails having a mid-girth greater than say 90% of the foot length.  So be sure to talk with your sailmaker to ensure your sail is designed for top down furling.  Otherwise, these larger sails will require a spinnaker sock, which is a good option but is not as easy to use or and space saving as a furler.

Remember to always consult with your sailmaker to ensure your sail, new or existing, is optimized for furling, and the apparent wind angles you will be sailing most often.  Call our team at APS if you have questions on the different features in bottom up or top down furler.  Proper planning will lead to trouble-free, and more enjoyable sailing.


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