Improving Roller Furling Efficiency

Posted by Darrell Nicholson at 05:14PM - Comments: (8)

One of the easiest ways to improve furling efficiency is to address line lead.

In the upcoming issue of Practical Sailor magazine, we look again at roller furling gear—one of the most popular upgrades on an older boat. The article documents the installation process on a Bristol 35.5 First Light, our New England-based test boat. During the process, the manufacturer provided plenty of guidance, and reiterated important advice—if you have to use a winch on your furling gear, there is a good chance something is wrong with the furler. And if you have to really crank down on the winch, there is a good chance that things will get worse. 

Headsail furling on sailboats 40 feet and under should be able to be accomplished with a hand-over-hand pull on the furling line. If a large genoa is set and the breeze fills in abruptly, it may take a little coaxing with a winch to get things going, but when it’s a fairly light wind day, and you need to start cranking away on a primary winch to instigate the furl, something is wrong with the system.

We have seen foils “barber pole,” or twist, due to excess tension on the furling line. Such scenarios usually involve torque applied at the drum and an upper swivel that refuses to turn. Bearing failure in the upper swivel is often the cause.

Systems with halyard blocks attached at the top-foil, which do not rely on upper swivels, never face this problem. But this style of furler is usually only used on boats 35 feet or shorter, and they have other sources of friction.

One of the easiest ways to improve the furling efficiency of all types of furlers is tackle the line-lead challenge. It starts with the angle that line leads on and off the drum, progresses into a sweeping arc as the line makes its way to the cockpit and ends with another change in direction that leads the line to the hands of a crew member or a winch drum.

All deflection away from a straight run creates friction, and the goal is to keep the accumulation of this parasitic load as low as possible. We noted that among the 20 furling-line fair leads we tested, none utilized metal ball bearings. (Look for the full report in the October issue.) High molecular weight plastics have taken over and they should get some occasional wash-downs to clear grit and salt from the exposed bearing races.

When it comes to cutters and double headsail sloops, or the addition of an endless line furler, we prefer to lead furling lines to opposite sides of the boat. This tends to make line-handling more straightforward, although it does increase hardware needs.

For more on the topic of furlers, check out the following reports. 

Refining Furling Line Fairleads

Fitting a Roller Furling Line

Headsail Roller Furlers

Heasail Furlers Sans Swivels

Riggers Advice on Furlers

These and other topics are covered in our 4-volume ebook Practical Sailor's Complete Look at Sails, available in our online bookstore, where all sales help support our testing program. 

Comments (8)

Hank-on sails don't jam, don't have dozens of parts and are virtually friction free going up and coming down. Every time. Plus, they set better and will get you to windward. I'll stick to hank-on headsails any day of the week.

Posted by: Lakota44 | September 22, 2019 2:47 PM    Report this comment

Any decent breeze and you really should head downwind and let the main block the wind.
Too many folk are reeling in with too much pressure on the sail. Find a lee shore.

Posted by: joesailboat | September 19, 2019 8:28 PM    Report this comment

Been having trouble on my 37' sloop. Looked at the line, the spool, the top has already had a mast mounted block added to stop top twist.... then I read the manual (last resort) carefully. The forestay being too loose can cause friction on the interior of the foil as well. Of course tightening your back stay can also tighten your fore stay so choose accordingly.

Posted by: Dino63 | September 19, 2019 10:55 AM    Report this comment

One must also remember that when you are unfurling the sail to not let the wind grab the sail and free spool out causing the line as it loads into the furler drum to create an override. A nice smooth release of the headsail by having someone keep a light hand tension on the furling line as you pull on the jib sheet will help ensure that when it comes time to furl the sail that there will be less chance of the furling line being trapped under itself. This is experience speaking loud and clear.

Posted by: Sam Steele | August 7, 2015 3:20 PM    Report this comment

Taking some pressure off the sail by pinching up also lowers the effort on the furling line.

I am sure that a few boat bucks on articulated blocks, as shown in the picture, instead of fixed fairleads would help too.

Posted by: Boston Barry | August 5, 2015 4:23 PM    Report this comment

And of course the lead angle should be perfect. The factory lead on my PDQ was off by about 5 degrees, making for difficult furling and resulting in rapid line wear.

Excessive down haul tension adds swivel friction. Some manufacturers suggest easing the tension off before furling. In my case, the sail cut requires very little tension.

Shortly after taking delivery of my new-to-me 14-year old boat, the lower swivel started to jam, the result of the Delrin bearings crumbling, causing furling difficulties, something I should have noticed this during the sea trial. Fortunately, it was easily rebuilt, and in my case I switched to lubricated stainless steel balls (I added a seal at the top to prevent rain and seawater washout). That was 6 years ago, and it remains smooth as glass.

For those with chafe issue on the furling line (used as a roller-furler the line will have load on it while sailing, and my Hood Seafurl is chafe prone). Using non-stretch line helps (less pumping movement), as does coating the vulnerable section with Spinlock RP 25 (good) or Yale Maxijacket (better). See Practical Sailor review March, 2015.

If worst comes to worse and the furler jams with the sail open (mine did), calmly remember that it is still a foil. Hopefully the masthead sheave and halyard have been maintained.

Posted by: Drew Frye | August 5, 2015 4:12 PM    Report this comment

And of course the lead angle should be perfect. The factory lead on my PDQ was off by about 5 degrees, making for difficult furling and resulting in rapid line wear.

Excessive down haul tension adds swivel friction. Some manufacturers suggest easing the tension off before furling. In my case, the sail cut requires very little tension.

Shortly after taking delivery of my new-to-me 14-year old boat, the lower swivel started to jam, the result of the Delrin bearings crumbling, causing furling difficulties, something I should have noticed this during the sea trial. Fortunately, it was easily rebuilt, and in my case I switched to lubricated stainless steel balls (I added a seal at the top to prevent rain and seawater washout). That was 6 years ago, and it remains smooth as glass.

For those with chafe issue on the furling line (used as a roller-furler the line will have load on it while sailing, and my Hood Seafurl is chafe prone). Using non-stretch line helps (less pumping movement), as does coating the vulnerable section with Spinlock RP 25 (good) or Yale Maxijacket (better). See Practical Sailor review March, 2015.

If worst comes to worse and the furler jams with the sail open (mine did), calmly remember that it is still a foil. Hopefully the masthead sheave and halyard have been maintained.

Posted by: Drew Frye | August 5, 2015 4:12 PM    Report this comment

You don't mention below-decks systems which typically use 2 90-degree turns to go below and back to the drum. This friction makes is difficult if not impossible to furl without a winch except in calm conditions. Are there better systems for below-decks?

Posted by: Robert, Long Island Sound | August 5, 2015 11:25 AM    Report this comment

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