The jib furler started out as a great idea but was plagued by serious mechanical flaws.  For years, cruising sailors, this author included, derided them as "roller-fooling" or "jib-snarling", and the standing recommendation was that every unit should come with a large crescent wrench and a life jacket.  But the concept of an easily wound-up sail is a compelling one and manufacturers worked hard to make furler engineering seaworthy.  They improved bearings, fasteners, and foils while redesigning drums and swivels for reduced furling effort and long unit life.  The result is that by 2000 furlers were far more reliable and efficient, which is why they are now nearly universal on cruising vessels and day sailors.

However, it is important to remember that when you install a furler, you have just hung a fairly complex machine on your forestay, and as we all know, machines have requirements that we can ignore only at our peril.  Just as with an engine, winch, autopilot or any other modern marine convenience, even the best furlers must be installed correctly and maintained over time to assure optimal performance and safety.  Because of the variations in furler design, each brand has specific needs, some of which will be detailed below.  But even given those variations, all furlers are enough alike that some advice can be applied to all of them.

For this article I relied on direct experience (our shop installs, services and sometimes despairs over many types of furlers), as well as tales told by other riggers.  But the most valuable contributions came from manufacturer reps.  This might not seem like a place to go for reliable information, but it really is.  To a certain extent, one can hear about a given brand's weak points from the competition, but mostly I have found that the reps we deal with on a daily basis are extraordinarily forthright, helpful and generous, even when it comes to considering the shortcomings of their own products.  As a group, they know that no machine is perfect, so it is up to them to provide the kind of information, upgrading, and generous warranty that will keep their customers happy.

I limited interviews to five major manufacturers: Schaefer, Harken, Hood, Profurl, and Selden/Furlex.  Partly this was because these companies account for most of the furlers in the world, and partly because they have the most experience with how a furler can survive and fail.  In the interests of clarity, I did not include electrical or hydraulic systems, nor in-mast or in-boom mainsail furling systems.

So how do you keep your jib furler alive?  You start by asking a series of questions and then do your best with the answers.  We'll begin with the wire that the furler hangs on. 

When do I replace the forestay?

The best time to install a furler is when you are due to replace all your standing rigging, preferably with the mast out.  That way you can recycle your old stay, and get a new forestay inside your nice new furler, all in one easy step.  If you cover up an old stay, figuring it still has life left in it, you could be causing yourself future trouble and expense.  When the time comes to replace the wire, you will have to lower the furler to deck, disassemble the furler at least part way, remove the old wire, insert a new wire, reassemble the furler, and send it back up.  That's why most manufacturers and riggers recommend going the new stay route, even if it means retiring a wire before you otherwise would.  Selden/Furlex feels strongly enough on this point that they include a new stay as part of their kit.  Every other manufacturer leaves you the option of keeping your old stay.

As Hood's Mike Haber puts it, "It's a judgment call by the rigger or customer.  People shop by price, so a new stay is a price shocker.  Our take is that if the wire is more than 4 years old, replace it". 

Selden's Scott Alexander adds, "Replace the forestay when you replace the other wires, unless the wire has been damaged by a halyard wrap or other problems" (see below for examples).  This applies when you are replacing an unsatisfactory furler with a new one or correcting a faulty installation.

And Mark Reuther from Profurl notes that, "A forestay usually doesn't age quicker than other wires, since they are somewhat protected from air, water, and chafe.  What is important to remember for standing rigging wires is to replace them as recommended for your part of the world".  This means that boats in the tropics, where the air is warmer, the water saltier, and the typical wind speeds higher, should replace their standing rigging much more frequently than a seasonally sailed boat on a freshwater lake.

What size furler do I get?

Every manufacturer makes a limited number of models, each of which will fit several sizes of wire.  And there is usually some overlap, so that a smaller, cheaper model will accept the same wire size as a larger, more expensive one.  This is because furlers have to fit so many different kinds of boats.  The forestay on a small, high-aspect sloop might have the same size furler as the forestay on a much larger cutter, with the only differences being in sail size and wire diameter.  So the real question must be: what size of stay and sail are best for this boat?  The area of the sail is usually easy, but wire diameter is a trickier subject.  It turns out that a sizeable percentage of boats are sailing around with the wrong size forestay, more often too large than too small.  This makes for added weight aloft, and added loads on mast and hull.  It can also mean that, if you go by the wire size you currently have, you might put the wrong size furler on your boat.  This could mean that you pay too much - and get even more weight, windage and rig load from an oversize furler, or that you put excessive loads on an undersize furler.  Or it could be as simple as the furler not having a big enough drum to fit all furling line onto for your sail.

Therefore, consult with the manufacturer (dealers are seldom wise in this department), or a rigger or naval architect before getting a furler, to determine the ideal wire diameter, with appropriate factor of safety, for the stay you are enfurling.  Also check with the manufacturer to make sure that furling line for your largest jib is going to fit on the drum, and that the furler is suited to the type of loads your boat will impose.  On this latter point, the reefed Genoa on an extremely stiff, fast boat will put huge torque loads on a furler, so you'd err on the heavy side, while a typical cruising boat will have the kinds of loads that most furlers are built to handle easily.

And if you're thinking of getting an oversized unit for easier furling due to more leverage from the larger drum, this is less important than having low friction in the furler bearings.  The correct-sized unit will have ample large, efficient bearings.

What maintenance do I need to do?

• Galvanic Action

  We always tell a client about the importance of proper maintenance for their furler and are often met with a, "Maintenance? what maintenance?" frown.  Too many people treat these products as some sort of Perpetual Furling Machine.  But furlers have bits that can fail and those bits need care. 

  Let's start with the foils, or tubes, on which the sail rides.  On nearly every furler the foil sections are aluminum tubes about six-and-a-half feet long that are connected by aluminum bearing holders.  Inside these bearing holders are the plastic bearings that ride on the wire.  There are a lot of variations on how this is done but with most brands, including Harken, Hood and Profurl, the aluminum foils and bearing holders are held in place by stainless steel machine screws.  Since these are tapped into aluminum there is a wonderful opportunity here for galvanic corrosion.  That is why it is vital to isolate the two metals with some form of anti-corrosive material, preferably with an adhesive such as Tuf-Gel or Loctite.  Adhesion is as important as anticorrosion, because in use the foil is spinning, bending and vibrating, which could cause unglued fasteners to work loose.  If that happens, you might be unable to lower the sail and the sections could even come apart.  Profurl screws come pre-coated with a thread adhesive, but it is wise to add some on your own as the coverage is not always complete.  Harken's units come with red Loctite in a separate container.  This is the high-strength stuff, but works only if you put enough on.  Hood actually treats all its fasteners with a black oxide coating for better corrosion resistance and a more receptive surface for the adhesive.

  On a Schaefer foil, the sections are held together with stainless pop rivets.  No need for an adhesive here but it is a good idea to dip each rivet in Tef-Gel before installing, to prevent a galvanic reaction.  Selden's foils are held in place with clever little aluminum buttons so corrosion is not an issue.

  Galvanic corrosion isn't limited to the foils.  You'll also find stainless and even titanium fasteners on some swivels and drum sections.  These fasteners must also be treated.  In some of these applications the screws are held by Nylock nuts.  In addition, vibration, bending, etc. might not be significant, so the treatment need not be adhesive.  The short form here is to apply an anticorrosive and/or adhesive any time two dissimilar metals are in contact.  If you've owned a furler for a while and have never rebedded the fasteners, don't be surprised if they are now impossible to remove without a drill press.  Galvanic corrosion can be a fierce thing, especially in a warm climate.  And if you can't get the fastener out, you can't do other maintenance and repairs.
   

• Bearings

  The bearings that ride on the wire inside the foil should be maintenance free, since they are hidden away from sunlight, grit, abrasion and abuse.  In addition, they each take only a small part of the total load.  It is possible to mess them up (see below), but not easy.  However, there are other more complex bearings in every furler: the ball bearings in the swivel and drum races that make the whole thing work.  These bearings are external, are often exposed to the elements and they must take concentrated loads, both in compression and tension.  Furler makers have taken several paths with regard to the design of these bearings, both in the materials that the ball bearings are made from, and in the design of the bearing races.  Harken and Schaefer make theirs from Torlon, a hard, resilient plastic that is also found in high-performance blocks.  The advantage of Torlon is that it requires neither lubrication nor sealing.  In fact, lubrication can actually do damage.  As Harken's Jim Bourne puts it, "Never, ever, ever oil or grease a Torlon bearing.  It just attracts grit." If you want to get a little extra efficiency, spray a little dry lubricant, like MacLube or Slide-all, on the bearings.  Other than that, all the bearings need is an occasional rinse with fresh water.

  Torlon's big drawback is that it can deform under sustained loads, the kind you might get on a days long ocean tack.  Harken and Schaefer compensate for this with bearing races that distribute the loads evenly among a maximum number of bearings.  Furlex takes a different approach, using deformation resistant stainless steel ball bearings in a semi-open race.  But stainless bearings need to be lubricated or they'll chew each other to pieces.  So Furlex bearing maintenance is a matter of a fresh water rinse and an occasional maintenance spray with WD40 or the like, to dissolve the old lubricant; soap and a hose to remove grit; and finally some fresh Furlex bearing grease.

  Profurl takes yet another approach, using stainless bearings, but permanently sealing them and their lubricant inside a remarkably durable double-lip seal.  No maintenance required here.

  And Hood's new furlers take one more design path, alternating Torlon and stainless bearings, to get the toughness of stainless and the just-rinse-it ease of Torlon.

  For any bearing that requires maintenance, how often you do it is a matter of climate and use.  In the North, once a year might be sufficient, while in the Tropics, once every six months might not be enough.  Schaefer's Fred Cook says that, "We do our best to make a durable furler, but to some extent, we depend on the common sense of the sailor using it.  If you use the unit hard, in a warm climate, it's going to require more attention than if you don't." Furlex's rule of thumb is, "You maintain the furler when you maintain the winches." Of course, there are also those who frown at the thought of maintaining winches.  But that's for another article.
   

• Assembly

  Too many people, amateurs and professionals alike, take a good furler and turn it into a very bad one, by installing it incorrectly.  Galvanic action can be slowed down or eliminated, bearings can be lubricated, but if you cut the foil the wrong length, put the swivel on upside down, disable the toggles, or any one of a dozen other common mistakes, no amount of maintenance is going to help you.  Every rigger has stories of large and small furler catastrophes, most of them traceable to a failure to take a close look at the manual. 

  As Mike Haber puts it, "Before you begin putting the unit together, take a step back.  Open the box.  Lay out & dry fit the pieces.  See that you have everything, and that it fits."  Variables include being sure that all the fasteners you'll need are in the box, and that they are the correct size, that the drum will not interfere with deploying the anchor, and that the toggles can move freely at stem and masthead (more on this below).  If this is your first time assembling this type of furler, you don't want to be figuring it out as you go along.  Rehearse, reread the manual, visualize.  If you do this sort of thing for a living, you might want to go over the basics once in a while; too many "professional installations" are simply those that are consistently wrong. 

  Some major details:
   

  • Sta-Lok  Fitting

    If you are installing a Sta-lok fitting, be very careful with the assembly process.  It's simple, but if it's wrong, the rig is coming down.  Sta-lok fittings are great terminals and can be installed by the inexperienced, but if this isn't the kind of thing you do a lot, consider letting a pro handle this job. 
     

  • Foil Bearing Holders and Bearings

    Most of the foil section bearings and bearing holders are no-brainers, lining up with screw holes in the foil, and/or locking into place automatically.  But since the top foil is almost always cut to fit a specific stay length, the top bearing is a special case.  On Profurl, for instance, it requires a special croissant-shaped insert and a screw to keep the bearing from dropping down into the foil.  Harken's does the same job on its top bearing with lots and lots of red Loctite.  Schaefer welds a little bead onto its top bearing holder, so it can't slip down, but if you're not paying attention, you might use a leftover standard bearing holder by mistake.  The top bearing must support the considerable lateral load of the swivel, so it is extremely important to get it right. 

    The next-highest load comes at the bottom of the foil, so pay close attention to the manual here, too.  If you have a Profurl, be sure to hold the foil up when adjusting the turnbuckle; if you let it fall down, it is possible for the impact to shear off the tabs that hold the bottom bearing in its holder. 
     

  • Halyard and Halyard Swivel

    A furler's halyard swivel is a wonderful device, enabling you to adjust halyard tension, even if the sail is furled.  But it is also a tremendous Achilles heel, being the source of the majority of the furler problems we see in our shop.  For example, if the halyard lead is too close to the foil, and especially if the halyard is slack, it can get caught up on the foil while you are setting or furling the sail.  This is the terrible "halyard wrap" that can make it impossible for the furler to rotate, or for the sail to go up or down.  And it can damage or destroy the foil, the wire and the halyard.  Accordingly, every manufacturer that has a halyard swivel is extremely emphatic on proper halyard lead and tension, as well as optimal swivel height.  Particulars vary, but the general idea is to have the top of the swivel just a few inches below the top of the foil and to have the halyard angled slightly aft from the swivel.  Profurl handles both these details with their "Wrapstop", a Darth-Vader-Helmet-like object that clamps onto the top of the stay.  Other manufacturers use "halyard restrainers" that clamp to the face of the mast, though increasingly spar builders are finally getting around to positioning jib halyard sheaves for an optimal furler lead, without the need for a restrainer. 

    Even if you have proper swivel position and halyard lead, you can still get a wrap if you stow your spinnaker halyard on the bow pulpit; even a little bit of slack can get this line entangled with the foil or sail. 
     

  • Foil Length

    Schaefer's Fred Cook admonishes, "Cut the foil correctly, I repeat, cut the foil correctly."  With a Schaefer, this means that there will be some wire showing above the furler when you install it.  With a Harken, it means that the foil will partially swallow the upper swage, or snug up to the Sta-lok.  Every manufacturer is very picky about foil length, so they provide heavily detailed descriptions of how to get this part right.  And for good reason.  For instance, we recently saw a forestay drop into the water, with the mast uncomfortably close to following it, because a professional installer made the foils too long, that resulted in the top foil jamming against the upper terminal, that resulted in that terminal unscrewing when the sail was furled.  The good news here is that manufacturers have spent a lot of time and effort in creating clear, detailed manuals.  But as Jim Bourne notes, "We have lots of charts & info in the manual, but you gotta read it."
     

  • How to Detect an Incorrect Installation

    Easy furling is an incremental process, and correct installation and usage will cover all of the increments.  If they don't, simple observation will often reveal the cause.  Or, in the wise words of Yogi Berra, "You can observe a lot just by watching".  With furlers, this means that attentiveness will reveal flaws, even where technical expertise is lacking.  If you observe that it is difficult to raise or lower the sail, it could mean that the luff tape is the wrong size, that someone forgot to install the prefeeder at the bottom, that one or more foils are damaged, or that some foil fasteners aren't down flush with the foil surface, among other things.  Furlex's Scott Alexander advises, "Most people think about ease of furling, but one way to detect a bad installation is to notice if it is difficult to set sail".  In other words, if the sail doesn't just leap off the foil, something is very wrong. 
     

  • The Furling Line

    This line must exit the drum at a 90° angle.  It helps if the lead block is as far aft of the drum as practicable, so the angle changes minimally as the turns go up and down on the drum.  After the first lead block, the rest of the lead blocks must deflect the lead minimally and there should be no intervening obstacles to chafe the line. 

    If you observe that it is difficult to furl the sail, your inclination might be to use the furling line winch.  While this is sometimes necessary, most often this is an indication that something is wrong.  A winch is so powerful it can mask the amount of effort required to furl.  You won't feel bearings are going bad until they seize up.  If a halyard wrap is the problem, the winch will turn the wrap into a stay and foil destroying disaster.  And Mark Reuther tells the tale of a boat overtaken by a storm, with the sail being rolled up in much higher wind speed than the crew ever encountered before.  This meant that the sail went onto the foil much tighter than it ever had, requiring more revolutions of the drum for a complete furl.  All of the line was off the drum before all of the sail was in, and instead of looking to see what the problem was, the crew took the furling line to the drum and cranked until the furling line broke.  The Genoa promptly set itself fully in a howling gale.  The lesson here: if you observe that there are just enough turns on the drum to furl the sail, then there are in fact not nearly enough turns on the drum.  Try for six turns of sheets around the furled sail with at least that many turns still left on the drum. 
     

  • Not the Furler's Fault

    Bear in mind that if your furler is giving you trouble, the problem might actually lie elsewhere.  Difficulty of hoisting could also come from a halyard that is badly led inside the mast; difficulty setting the sail could be caused by too much tension on the furling line as it winds onto the drum; and difficulty furling could be caused by inefficient or poorly-aligned furler line lead blocks, or most often, because there is too little tension on the furling line when you set the sail, so the turns on the drum are loose, so they bind under each other when you go to furl.  Eliminate these possibilities before tearing into the furler. 
     

  • Halyard Tension

    If you have an adjustable backstay, set the halyard tension for light-air conditions, with the backstay slacked for the same conditions.  That way both stay and halyard will get appropriately tight as the backstay tension increases.  If you have a racy boat, capable of large changes in rake under way, you'll find it necessary to adjust the halyard tension with each rake change.  In either event, what you want to avoid is starting with a tight halyard and slack backstay, because tightening the backstay could easily rip the furler and/or sail apart. 
     

  • Tune and Rake

    While not directly a furler issue, the tune and rake of the mast can affect both the furler and the rest of the rig.  First, as mentioned above, it's a good idea to double-check for appropriate wire diameter before installing a furler.  It's also a good time to see if the mast is raked appropriately, so you can fix that if necessary, before installation.  And it is a very good idea to check rake after installation, to make sure that you or the rigger got the stay measurements correct. 

    Tune is a related subject, in that a mis-cut stay might result in an unwelcome amount of bend in the mast, or a backstay turnbuckle that bottoms out, yet still leaves the forestay too slack.  We see amazingly distorted post-furler rigs, generally traceable to inadvertent stay length changes made during installation.  So I repeat, make sure the forestay is the correct diameter and length, pre-furler, and make sure it is still the same length after. 

    A little more on tune: aside from structural and performance benefits, tuning has a strong effect on furler operation in that the sail will be easier to furl when the forestay is tight.  This is because the unit will oscillate less as it rotates.  Conversely, when the boat is at rest, it makes sense to slack the backstay a bit to reduce rig load on the hull.  The problem is that the furled sail will cause the foil to oscillate on the slack stay even more than it would under way.  As a result, there will be a tremendous fatigue load on the toggles, particularly the upper one.  This load has lead to a number of rig failures.  The fix here is to limit how much you slack the backstay.  It must never, ever, be dead slack. Snug up the sheets when the sail is furled, to prevent oscillation. 

    In any event, installation is much more than just plugging a machine into the rig.  It is more a matter of integrating it, for optimal safety, efficiency, and durability. 
     

  • Toggles

    Even a properly tuned stay will deflect under sailing loads, so it is imperative that there be toggles at both ends of the stay.  For the toggle at the top, see that it can't bind on the masthead and that it doesn't have to be deformed or reshaped in order to fit into the masthead.  If it won't go as is, you need a different form of toggle. 

    At the bottom, make very sure that the link plate that holds the drum up doesn't disable the toggle.  Likewise, check that the stem itself doesn't jam the toggle into immobility in one or both planes. 
     

  • What's Hidden?

    More than one vessel has been dismasted because the rigger forgot to cotter the forestay turnbuckle, which is completely hidden inside many furlers.  The stay itself can be of poor quality, or damaged, but it's hidden too.  And a badly assembled Sta-Lok looks just like a good one, from the outside.  Look inside. 
     

  • Sunshield

    Most roller-furling jibs have a UV-resistant patch that runs up the leach and foot so no unprotected cloth is exposed when the sail is furled.  But even if you do every little thing else perfectly, you still have one more chance to ruin the whole thing by running the furler line onto the drum backwards.  If you do this, you'll end up with the patch on the inside and have frying Dacron on the outside.  It happens.

Conclusion - Good engineering, tempered by decades of seagoing experience, has resulted in today's jib furlers, and today's information on furler maintenance.  The machines themselves are long past the experimental stage; as with any other seaworthy device on a sailboat, the problems you might encounter are likely to come from error or negligence.  Assuming you can eliminate those problems, which furler is for you? As a rigger, I have my preferences, but the good brands are all so good that it was very easy to be impartial in the preparation of this article.  So if you already have a jib furler on your boat, I would urge you keep up the maintenance.  If it is old, cantankerous, or in any way less than ideal, I would urge you to look especially closely at it, and consider a newer model.  And if you are shopping for a furler, I would urge you to do your homework on size and suitability as well as price and availability.  Get a unit that rotates freely under load, and not just at the boat show.  Get one that is durable, easy to inspect and to service.  Then do your part to keep it alive.
 

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