Considering a Headsail Roller-Furler
by Dan Dickison
There’s no denying the popularity of roller-furling systems for headsails these days. For ease of handling and convenience, they’ve long been used aboard cruising vessels, and in the last two decades they’ve have become standard equipment on a number of popular racing designs, like Melges 24s, Ultimate 20s, J/105s, and many others. In part, these devices are so ubiquitous because they’ve evolved to be quite reliable, and because they’re engineered for a number of different applications.
This doesn’t mean that every sailboat owner has operational familiarity with them, and it’s not difficult to imagine that questions might exist regarding what kind of furling product or what size might be right for a particular boat. Further, there might also be questions about the kind of features a sail might need to be retrofit for use with a particular unit. To begin addressing such concerns, here’s a brief primer.
Furling units ordinarily consist of a line-driven spool or drum mounted on the headstay at deck level along with a free-wheeling unit at the top of the stay. With most systems, these top and bottom components are connected by extruded aluminum tubes that have been fit over the headstay. Most furling designs work by having the drum, upper unit and the connecting tubes spin around the headstay with the tack, luff and head of the headsail affixed to them so that the whole assembly rotates to furl or unfurl the sail. The majority of furling units use ball bearings in both the drum and the upper unit so that they can rotate with reduced friction, but there are some units on the market that simply rotate around the headstay without the assistance of those devices.
Most existing headsails can be adapted for use with roller-furling units, and roller-furling units can be installed aboard almost any kind of sailboat. However, since these systems are normally sized according to diameter of the headstay and its clevis pins, it’s important to order or purchase the correct size furling unit for your particular rig. Most manufacturers offer products that accommodate a variety pin diameters, and most furling units can be installed without unstepping the mast or cutting the headstay.
The most commonly used furling units are either direct-drive or spool-wound. With the former, a continuous line leads forward from the cockpit to the furler where the line is rove snugly through a sheave/sprocket and then back down the other side of the boat to the cockpit. The tight fit of the line in the sheave/sprocket causes the furling unit to rotate when the line is pulled. Spool-wound furlers are also controlled by a line led to the cockpit, but in this case the line is wrapped around the spool or drum of the furler multiple times so that when it is pulled, it causes the drum to turn and thus furl the sail. Direct-drive units are ordinarily lighter than spool-wound furlers and offer the advantage of a lower placement of the sail’s tack should that be desired. For sails on much larger boats, there are also hydraulic or electric furling units.
When selecting a headsail-furling system for an existing sailboat, consider that good quality materials are needed to stand up to the marine environment. Some manufacturers use steel bearings while others prefer hard plastic bearings (like Torlon or Delrin), which won’t rust. Additionally, some units are designed so that the bearings are sealed, where others are semi exposed, which makes cleaning and lubricating them an easier task. As with any marine product, investigate the components to make sure that they’re either fashioned from the same kind of metal or in the case of dissimilar metals, they’re insulated from one another.
If you add a furling unit to your rig, it’s possible to do so using the existing turnbuckle and headstay, but some manufacturers caution that turnbuckles should be appropriately sized to handle the side loading that a partially furled sail will create. It’s best to check with either a rigger or the roller-furling manufacturer’s rep regarding that.
If you do decide to retrofit your boat with a roller-furling unit, it is possible to use your existing inventory of headsails, if they are in good shape. The sails, of course, will require some modification. If your sails hanks on the luff, you’ll have to remove the hanks and add a luff tape so the sail(s) will slide into the groove on the foils (extruded tubes) that span from the top to the bottom furling units. And, if you’re modifying large headsails, there’s a strong chance you’ll have to shorten the luff to accommodate the drum at the bottom and the swivel at the top.
If your intent is to use your furling unit to “reef” the headsail, you’ll want to have a sail that is designed for this purpose. This usually means that sail has had a tapered section of foam sewn into the luff area, which helps the sail retain a more performance-oriented shape when partially furled. This is really a crucial area to discuss with any sailmaker. Without the appropriate shaping device added to the sail, a partially furled sail will become smaller, yes, but fuller in shape, and that’s the opposite of what you want for increasing wind strengths.
If you already own a boat with roller-furling system for headsails, and you’re shopping for a new headsail, a different set of considerations come into play. You’ll have to determine what size sail you want, a decision that should be based principally upon the kind of sailing you ordinarily do and the prevailing conditions where the boat is kept. Most owners opt for a sail that is designed and built to be used both fully unfurled and partially furled. This gives the sail the ability to be used in a greater range of conditions. If this is what you seek, make sure that the sail not only has the appropriate shaping devices, but also has sufficient reinforcement for the additional loading that will occur while it’s partially furled. Finally, your sail should be built with ample sun protection. Most sailmakers add a generous swath of sacrificial cloth along the foot and the leech of the sail for this purpose. Ask your sailmaker how long this protective cloth will last, and find out beforehand what you need to look for as that cloth nears the end of its predicted useful life.
In more recent years, furling systems have been designed for use with spinnakers and gennakers, which make the handling of these sails much more manageable. These usually are self-contained units that are stored with the sail furled and simply hoisted by way of a spare halyard when needed. In most cases, a wire or high-tech line integrated into the luff of the sail connects the upper swivel to the lower furling drum or sprocket.
Regardless of the application you have in mind, it’s best to consider all the pros and cons before adding a roller-furling system to your boat. Below is a brief list of those to keep in mind before you make your decision.
Pros and Cons of Furling Units
Pro: Enhance safety on board because their use normally means fewer trips to the foredeck for the crew.
Con: Can inhibit performance due to additional weight in the bow and up the rig.
Pro: Aboard cruising boats, they usually mean a higher cut foot, thus enhanced visibility forward and easier egress for green water on the deck.
Con: Moving parts that require maintenance and can malfunction unexpectedly.
Pro: Make it possible to vary a vessel’s sail plan from the safety of the cockpit. Good for shorthanded crews.
Con: Sails are usually left hoisted when not in use, thus subjected to UV degradation.
About the Author: Dan Dickison is known throughout the sailing community for his in-depth articles on a variety of sailing topics. His resume includes stints as a staff editor at Sailing World, Editorial Director of SailNet, and Editor of Practical Sailor. In those capacities he has written principally about racing, sail handling, and maintenance. He has also written over 50 freelance articles that have appeared in major sailing publications around the world.
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