In-Boom Furling: Five Systems


Our last good look at in-boom furling systems was in the August 1, 1998 issue, when we liked both ProFurl and Leisure Furl, giving the edge to the latter despite its greater cost. The recent introduction of Schaefer’s new in-boom system gives us an excuse to revisit the subject and the systems in the field.

In-Boom Furling: Five Systems

From the outset we’d acknowledge that with each passing year, sailhandling systems get more and more refined and efficient—never mind the days of footropes and gaskets, of one hand for the headsail and one for yourself during routine jib changes.

Even so, the mainsail remains a challenge. Stacking systems, lazy jacks, the Dutchman, in-mast furlers… all contribute their share of convenience and control, but none has proven to be the answer. Stowing, furling, and reefing the main is still a sizable chore, especially as the size of your boat increases. And, as always when we attempt to conquer the considerable forces of wind and wave by mechanical means, we tread a fine line between convenience and chaos.

In the late ’80s, Hood Systems introduced the Stoboom, and rolling the sail inside the boom became an option. More affordable and less risky than furling the main inside the mast, these boom furlers were a big hit. However, the newly-engineered hardware proved to be more complicated and ultimately less convenient than it looked. It was, according to one owner who sailed a Hunter 42, “the costliest consumer mistake I ever made.” 

The sail entered and exited the Hood boom through a narrow slot in the top of the tube. For that and several other reasons Stobooms proved  jammable. They were also  fickle in terms of boom angle, and costly in terms of luff chafe. Hood tried education (a special aftermarket owner’s manual) and hand-holding (extensive customer service) before eventually pulling the Stoboom off the market. “However,” says Paul Boyce of Hood Yacht Systems, “we’re still involved in in-boom furling with hydraulic systems fitted to larger boats, most of which are in Europe.”

The advantages of in-boom furling that prompted Hood’s “noble experiment” have not disappeared with Stoboom. Compared with in-mast furling, the boom-based systems weigh less and keep weight lower. Probably the most significant selling point of a sail that lives in the boom, however,  is its shape. In-mast furlers require roachless, high-aspect triangles, thus reducing mainsail area, distorting ideal shape, and lessening draft control. We’ve talked with sailmakers, and most peg the overall performance loss that you’ll pay for the convenience of in-mast furling at 20% or worse. With a boom-furling system you can assure yourself of a powerful modern sailplan with plenty of roach, with the additional bonus of being able to use full-length battens to help control sail shape and reduce flogging.

There are other plusses—freedom from reefing-line clutter, variable sizing potential, automatic sail-covering, and the ability to retain your original spar, to name a few—but to us the most telling difference is safety: If an in-mast furler jams it’s probable that someone will need to go aloft to free it. Until then, you’ll be stuck with a hoisted mainsail in what may be exactly the wrong conditions. A jam in the boom can be addressed from on deck. If all else fails, just drop the sail as you would a normal main and furl it on the boom instead of inside.

But boom furling has plenty of detractors. Butch Ulmer, veteran sailmaker from City Island, NY, feels cautious about it: “The geometry still needs to be worked out. Big roaches drive battens forward. Overcoming that friction isn’t easy and it’s certainly not automatic.”

We asked the owner of a 73-footer who undertook a complete and costly refit why he hadn’t put a boom furler aboard. “I don’t need a $20,000 sailcover,” he replied.

Peter Harken, whose company makes headsail furling systems, said “We haven’t gotten into in-boom furlers because we think there’s a better way. We may be a bit prejudiced, but we feel that the batt-car system we’ve devised is the safest, surest, easiest way for getting a sail up and down easily and when you really need it. I  can just about guarantee those cars won’t jam, and you can’t say that about anybody’s boom-furler. Most of these systems work most of the time, but when you really need it, give me something that’s simple and foolproof.”

The In-Boom Furling Field
Today there are five in-boom systems on the market. We’ve sailed them all, noting design, construction, and performance. Given the conditions, we did our best to see how each delivers on the promise of boom furling. And at what price?

One overall conclusion is that, while Stoboom may have spoiled the boom-furling parade for lots of sailors, today’s systems really work. We put the gear through paces that occasionally created problems, but those snags never kept us from executing our set/reef/reset/douse evolution.

Schaefer and John Mast have relatively narrow openings in the top of their booms, but among the others there’s a trend toward open-topped extrusions.

You can still hold the boom up with a topping lift while rolling the main in, but all the systems we saw used a fixed, solid vang to do the job.

While you can get by without power winches, the whole process of setting and reefing, especially singlehanded, is easier if your winches have power. This is not to say that there isn’t a certain swashbuckling appeal in rolling the sail with one hand cranking the self-tailer and the other easing the halyard (keeping good tension for a nice tight roll).

Though they share the same basic idea, the five systems are significantly different. So are the companies that produce them. Leisure Furl has been around since the early ’90s, and its track record and testimonials are impressive. Schaefer Marine, a well-established hardware company, on the other hand offers a new system born of three years of design and development, but without much time in service. ProFurl engaged in extensive aerodynamic testing and material analysis before introducing a boom-furler just over three years ago. The big French company with dealers in 52 countries has since been energetic in promoting boom-furling to both the general public and among sailmakers.

Furlboom (“designed and built in Australia by Aussie yachtsmen to suit our rugged sailing conditions”) has had a varied career and is now built and  sold by the recently-formed Yachting Systems of America in Costa Mesa, CA. Like Leisure Furl, the company has concentrated efforts on centralizing manufacture and now offers a system that is entirely American-made.

The John Mast (JM) Hi-Low Reefer is imported from Denmark by Lars Pedersen of Bente Trading Company, Mercer Island, WA. Pedersen has long been a boom-furling zealot; he worked with the Danish mastmaker to develop the system. Over 1,500 boom-furlers have been  sold in Europe since 1990.

Leisure Furl
Over a decade ago New Zealand sparmaker Don Baverstock first came out with his roll-up system. Today KZ Marine, for whom Baverstock is a consultant, claims that “over 85 % of the new boats launched in New Zealand have our booms.” Says Bill Hanna at Forespar, US manufacturer of Leisure Furl, “Our system began with bigger boats and has evolved into boats closer to the everyday as it has gone along. The point is, we’ve been dealing with loads that are very significant right from the outset.”

Click here to view Leisure Furl images.

The first thing you notice about the Leisure Furl system is that the boom is virtually topless, with a wide “gutter” covered by a clever sliding sail cover. It has an attractively tapered silhouette and affords the convenience of letting you see and service the innards. The two key elements in the furler, however, are its “through-the-mast” drive shaft and the universal joint that joins it to the mandrel at the gooseneck. The “free-floating” universal means maximum power can be applied to rolling the sail. (Leisure Furl is the only manufacturer to use a universal; the other four systems rely on drum drives).

“We found it incredible that we could furl downwind in 50 knots in Bass Strait in the Sydney-Hobart Race,” reports one user.

Chuck Poindexter (Sound Rigging, Essex, CT) has installed 14 Leisure Furl units. “I was surprised to learn when we had a naval architect do the calculations that the drive shaft actually strengthens the mast…by 11% to be exact. When I first got involved it was because a customer wanted me to survey the gear on a boat that had made one and a half circumnavigations. It had a Leisure Furl. I ‘dissected’ the universal and it was perfect.”

Other components include a foot groove halfway from tack to clew. It captures a short bolt rope on the middle third of the sail, holding it to the mandrel. With a loose-floating tack and two-part clew pendant you can roll the sail (similar to the first rolls of a custom-luff headsail) so that the middle rolls in while tack and clew stay loose. What this gives you, we soon realized, was a flattening reef that offers an elegant range of draft control by adjusting the furling line while keeping the halyard tight.

A significant difference between systems is how they attach to the mast. Leisure Furl uses a conventional luff tape, captive in a “self-aligning” feeder that leads to a fixed luff groove. Dr. Robert Leaf, one of the first Americans to put Leisure Furl on his boat, had a big problem “chewing up luff tapes to the tune of three or four a season.” Cutting sails to minimize “pullback” and new, tougher luff tapes seem to have solved the problem.

“It’s how the sail drops at the tack,” Poindexter says. “If it drops right onto the mandrel you’re fine. I’ve been impressed that Leisure Furl has continued to evolve and improve.”

With halyard tension and boom angle you can control how your sail rolls onto the mandrel to a large degree.

Leisure Furl’s chafe problems at the tack seem to be its biggest Achilles Heel, and one to which sailors can address themselves as they learn their systems.

Leisure Furl is moderately encouraging about retrofitting your old mainsail to suit the system, but we wonder if it isn’t something of a false economy to marry top-of-the-line furling gear with a recycled sail, given the critical nature of how the sail fits and is reinforced. Because of the number of components, relationships, and variables, we think Leisure Furl’s “riggers only” installation scheme makes sense, too.

John Mast Hi-Low Reefer
This reefer is the departure point from which the others have developed. The main idea at its inception was to make boom furling easy and accessible. Judging by the more than 1,000 boom furlers now afloat in Europe, it worked. The Hi-Lo gooseneck bracket is adjustable, and job one is mounting it to your mast.  The boom is open at its forward end for sail access and transfer. The sail’s bolt rope is inserted in a flexible PVC luff track, which can be fitted to the mast in different ways. The system is simple and works well, but it does not appear as solid as its rivals. (Even the furling drum looked somewhat undersized to us.) When we rolled in a reef (using a handheld electric winch grinder) a pleat formed along the boom. Rolling the sail out to re-reef did the trick, but the full-length battens pushed forward of the mast track and created more friction than we thought reasonable.

Click here to view John Mast Hi-Low images.

With the John Mast and the other in-boom reefers it’s best to reef down to a full-length batten, which can then help support the foot of the sail. Being incompressible, it acts like an outhaul to keep the cloth stretched well aft. “Infinite” reefing between battens is discouraged.

Schaefer Marine
Fred Cook at Schaefer says, “We’ve studied some of the problems associated with boom furlers for quite some time and tried to come up with answers.”

To reduce friction the company’s new design incorporates four bearing races, two at either end of the boom. Made of Torlon, the bearings require no lubrication and are meant only to be flushed occasionally with fresh water. Hoisting the sail by hand felt significantly easier than with any of the other systems.

Click here to view Schaefer Marine images.

To handle the transition between the mandrel and the mast groove Schaefer developed a unique and practical  “sugar scoop” guidepiece. While we tested only in medium (12-15 knot) air, it seemed superb at sliding the sail back and forth from mandrel to luff groove.

The drum is mounted on the after end of the boom and worked via a single control line. The gooseneck pivot pin is hefty and made from 316-stainless bar stock. We wondered if the luff groove, a UV-resistant polymer, was as sturdy as the rest of the unit, but from the flogging that we put it through on our test sail it seems ready to withstand realistic abuse.

The track articulates with the boom, and this makes power-reefing (without completely depowering the sail) possible.

It’s good seamanship to take the strain off sail and gear by luffing the sail and/or bringing the boat into the wind when it’s time to reef or douse your mainsail. In a race, or due to navigational needs, however, this isn’t always possible. With the Schaefer system (and all others except ProFurl) you can reef without totally depowering the sail if you must. We think that adds to a system’s versatility and tolerance for error.

ProFurl puts its furling drum (very similar to a headsail furler) at the forward end of its open-topped boom. ProFurl’s other salient feature is its  articulating luff track mounted aft of the mast. Positioned to pick up and deliver the luff tape directly from the boom, this set-up has proven chafe-free. According to tests  conducted at France’s Research Center for Nautical Architecture and Industry, the structure actually increases mainsail efficiency by energizing the airflow over the sail.

Click here to view ProFurl images.

As with all of the mainsail furlers, the angle between mast and boom (or tack angle) is critical. Like most of its competitors, ProFurl specifies an angle of “about 87 degrees.” We found that this precision wasn’t absolutely necessary. If the boom is cocked up a bit more than perpendicular it pulls the sail aft and helps it lie smoothly in the boom. Lower the boom end, however, and the sail will bunch at the forward end of the boom, leading it to jam.

ProFurl provides a mechanical vang with a limiting wire: Release the vang and it sets the boom at the right height for furling. Reef the sail, then trim on to adjust vang tension for shape control.

We did all of that, and were rolling a reef in when, in an effort to stop some of the sail’s considerable flogging, we took just the slightest tension on the mainsheet. The sail immediately bulged larger at the forward end of the mandrel until it would no longer roll. We reset and re-reefed with no problem, but the incident made us mindful of  the delicate balance involved in boom furling.

Retrofitting your old sail is possible. One sailmaker advises, however, to “throw out the ProFurl formula for dealing with luff curve. Anything greater than two inches of luff round is too much, period.”

ProFurl USA in Fort Lauderdale says installation of its unit is “relatively simple.” Their elaboration: “An owner with some mechanical savvy and a rivet gun can do it himself, but it takes 16 man-hours and some work aloft.”

ProFurl has recently gone to ball-bearing sheaves, and wire halyards can now be used with the systems, which come with a three-year warranty.

One of the secrets of this furler is the way it’s built. “We have gusseted corners that make our entire extrusion structural,” says Dougal Johnson at YSA. “That lets us build a lighter, smaller boom that is still more than strong enough to do the job.”

The Furlboom drive mechanism is mounted on the after side of the mast and connected via a drive chain to the mandrel. We’ve heard of one of these chains failing, and think that provision for a manual backup would improve the system. An excellent feature, and one shared with Leisure Furl, is a locking mechanism that takes the strain of holding the sail in place once the sail is set (or reefed). This ratchet engages under spring tension and is released by a trip line controlled from the cockpit.

Click here to view Furlboom images.

Like most of the other systems, Furlboom employs a claw inside the boom. This guides the sail, both coming and going, and helps to assure a uniform roll. This is one of the several design features that enables Furlboom to handle rigs with considerable pre-bend (up to 8 inches, according to Johnson).

Like many of the systems we looked at, this one has had success on the race course. Johnson points to a Catalina 470 that came in fourth in class in the recent Ensenada Race. Toby Ritter, who took us for a demo sail aboard Tiger Too in Long Island Sound, raced  his Furlboom to Bermuda. However, when you see the slick “automatic” sail cover that you can slide into place once the sail is put to bed, it underscores the fact that you can’t knock boom furlers for cruisability.

The thing we liked least about in-boom furlers is the intimidating welter of controls, prohibitions, and caveats that go with them. There are plenty of reports of furlers gone bad, despite the reasonable efforts of their owners. In any case, sailors should be free to explore their limits and develop mastery of them without undue fear of expensive failures.

The thing we liked most was the amount of research and development talent that this rolling target has attracted. Chart the progress from Stoboom to the present and you’ve got a record of innovation and clever design that makes the marine industry look pretty smart.

It’s hard to assign ratings to systems we’ve only evaluated short-term, and not in conditions that might demonstrate the survival of the fittest. But here are some basic assessments:

The John Mast reefer is an older design, and the company has yet to establish an aggressive sales presence in North America. Its unit for a maximum P (mainsail hoist) of 42 feet is $6,850. This includes a boom vang, but not a sail.

ProFurl gets high marks for convenience and quality. A 42-foot P unit retails for $7,920, including a solid vang and boom brake.

Schaefer’s promising unit looks like it will fill the need for a simpler system that people with small to mid-sized boats can use and afford. A reefer to accommodate up to a 44-foot P retails for $7,500. The boom vang is not included.

We think that Furlboom is an excellent value at $7,250 for a 42.6 P length sail, despite the fact that the boom vang is no longer included.

Leisure Furl still strikes us as the most-rugged, best-proven unit. To match up to a 50-foot luff length you will need to pay $9,300. Installation, boom vang, and a new sail will boost that price a lot. If you’re willing to pay the freight, that reefer will render good service and excellent convenience, but our feeling is that Leisure Furl’s competitors have closed the gap and make attractive alternatives.

Contacts— John Mast Hi-Lo, Bente Trading Co., P.O. Box 1621, Mercer Island WA 98040; 206/232-6156; Leisure Furl, Forespar Products Corp., 22322 Gilberto, Rancho Santa Margarita, CA 92688; 949/858-8820; FurlBoom, Yachting Systems of America, 350 Kalmus Drive, Costa Mesa, CA 92626; 714/437-9600; ProFurl, 401 N.E. 8th St., Ft. Lauderdale, FL 33304; 954/760-9511; Schaefer Marine, 158 Duchaine Blvd. New Bedford, MA 02745; 508/995-9511;

Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 45 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. Darrell is booking speaking engagements in Colorado, Idaho, California, the Pacific Northwest, and British Colombia this summer. You can reach him by email at


  1. I have a 1982 sailboat (Classis 35, based in Rome, Italy) with an equally old Hood Stoboom. Except that it’s different from the one you describe: the sail does not furl inside the boom but around it. Were there different models. Incidentally, it works fine, you just insert the handle in the endless furler and roll the sail down while slowing the hailyard with your other hand to maintain some tension in the sail. With the autopilot you can furl the sail single-handed in a couple of minutes or less. I suppose there are some disadvantages with ’round the boom’ furlers since they are so uncommon and would like to hear about them.

  2. Well, you’re talking to a guy in Maine…..but I didn’t write this article. I was referred to it by friends in the Cape Dory Association because I asked about their experiences with either in-mast or in-boom furlers. I’m thinking of putting some such rig on my Cape Dory 36.

    I can make a comment, however, about your own experience. The Pierson Vanguard 33 had a mechanical boom furler rig available as far back as 1963. The current owner, who inherited the boat from her father and has sailed it all those years, said her father never used it….not has she. They both preferred to wrestle the sail down in the traditional manner. Great for the young folks….but I’m 76, and hoping to sail, sometimes singlehanded, for 15 more years.

  3. Hi Jim, and thanks for replying. You don’t say what their problem was, perhaps it depends on the model. As I said, the Stoboom, or at least my Stoboom, contrary to what the article says, does not roll inside the boom but around it making it much less likely to jam. At least mine never does and reefing or pulling down a snap, you just turn the handle and it’s done, no need to pack the sail as the boom moves back and forth under you. I’m sure they must have some modern equivalent but I don’t know about it.
    Congrats on sailing single-handed.