Roller Furling Jibs

01
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How Jib Furling Works

Jib Furler Drum
Photo © Tom Lochhaas.

Before the development of furling jibs, the jib had to be hanked onto the forestay with a series of shackles running the length of the sail’s luff. While hanked-on jibs are still used on many racing boats, on which sail changes are common, furling jibs are used on most cruising boats, especially midsize and larger boats.

At the base of the furling unit is the furling drum. Above it (hidden under the sail in this photo) is the furling foil, a flexible grooved structure that surrounds the forestay from the drum to a swivel at the top of the stay. The jib is hoisted with its leading edge in the groove of the foil—typically only once at the beginning of the sailing season. Then the furling line is pulled out of the drum, causing the drum and foil to rotate and the jib to roll up around the foil.

With a furling jib there is no need lower the jib and remove the sail hanks after each sail. A furled jib always remains raised and ready for use.

Remember to monitor changes in the wind so that you can furl in the jib early when it's easy rather than late when it's difficult or dangerous. You can learn to read the wind or use an inexpensive handheld wind meter.

The following pages explain the furling and jib reefing process.

02
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The Furled Jib

Jib Furler Step 2
Photo © Tom Lochhaas.

Here's a view of a tightly furled jib rising above the furling drum.

Note the blue protective cloth along the sail's edges completely covers the white sailcloth when the sail is furled. This is important protection against the sun's UV rays, which gradually break down the fabric used in most cruising sails.

03
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Jibsheets to Furled Jib

Furled Jib Step 3
Photo © Tom Lochhaas.

The jibsheets remain shackled to the clew of the jib, which rises higher on the forestay as the sail is rolled up.

The jibsheets may be tied to the clew using a bowline or shackles. The jibsheets in this photo are attached using a soft shackle, which avoids large knots or heavy metal that could be dangerous to a crew wrestling with a flailing jib.

04
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The Furling Line

Jib Furling Line
Photo © Tom Lochhaas.
The furling line coils around the furling drum and runs back along the deck to the cockpit. Pulling the furling line causes the drum and furling foil to rotate, which rolls the jib into its furled position.
05
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Unrolling the Furled Jib

Unfurling Jib
Photo © Tom Lochhaas.

The jib is brought out for sailing by pulling the jibsheet from the cockpit. Pull the jibsheet on the side on which the sail will be positioned, opposite of the direction from which the wind is coming. If the wind is crossing the boat from the starboard side, as in this photo, then the jib is pulled out on the port side.

The furling line must be released to allow the sail to unroll, but keep tension on it as the jib comes out to prevent snarling the line on the drum. The furling line should wrap neatly around the drum as the sail comes out, making it easier to pull the line later to roll the sail back up.

06
of 07

Keep Tension on the Jibsheet and Furling Line

Unfurling Jib Step 6
Photo © Tom Lochhaas.

As you continue to pull out the jib with the jibsheet, enough of the sail will soon be exposed to catch the wind. Be sure to keep tension on the furling line to prevent the jib from rushing out all at once and flailing in the wind.

Also keep tension on the jibsheet so that the sail keeps better shape. Usually it is necessary to put the jibsheet on a winch, once the sail catches the wind, and to start cranking the winch to bring in the sheet as the sail unfurls. Ideally, try to keep the jib in trim for your point of sail as it unrolls.

When the jib is all the way out, cleat the furling line and trim the jib using its telltales.

In windy conditions, you may not want the jib fully unrolled. You can reef the jib by leaving a few wraps of the jib still furled.

07
of 07

Adjusting the Jibsheet Block

Jibsheet Block
Photo © Tom Lochhaas.

On most sailboats with a furling jib, the jib sheet comes back to a moveable block mounted on the deck, as in this photo. This block can be moved forward or aft for optimum sail shape with different amounts of sail unfurled.

Moving the block forward pulls the clew downward more than back, tightening the sail's leech more than the foot. Moving the block aft pulls the clew back more than down, tightening the sail's foot more than the leach. Find the ideal position by watching the jib telltales at the top and the bottom of the luff in order to have both the top and the bottom of the sail in trim.

Sailors usually mark or note the ideal block position for the sail when fully opened and when partly reefed. It is much easier to move the block when the jibsheet does not have tension on it, while the sail is either furled or on the other tack.

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Your Citation
Lochhaas, Tom. "Roller Furling Jibs." ThoughtCo, Mar. 3, 2017, thoughtco.com/roller-furling-jibs-2915488. Lochhaas, Tom. (2017, March 3). Roller Furling Jibs. Retrieved from https://www.thoughtco.com/roller-furling-jibs-2915488 Lochhaas, Tom. "Roller Furling Jibs." ThoughtCo. https://www.thoughtco.com/roller-furling-jibs-2915488 (accessed November 18, 2017).