SJ23 Tech Tip F10b - Jib Conversion to Roller Furling

SJ23 Tech Tip F10b, (Updated 2023-09-08) Bob Schimmel

Jib Conversion to Roller Furling - With Jib Sleeve.
Index - Convert Jib to Furling, Typical Furling Operation, Pennant & Spinnaker Halyard Wrap, Jib Sleeve.

After installing roller furling now you have to make a decision about the jib; convert your Clark Sails hank-on 110% jib to roller furling or buy a full hoist roller furling jib; new or used.

Its fairly straightforward to convert a hank-on jib to roller furling by removing the old luff, head and tack fittings then sewing on new luff tape using a heavy duty zigzag sewing machine equipped with a walking foot. This is a low cost conversion of a sail that you know fits your boat. Before you start, confirm that your luff length fits within the foil length. It should got to full to full hoist. A furler requires this exact fit. To make an accurate measurement of your hanked jib, the luff bolt rope should be released (cut) inside the hem. Problem is, cutting the bolt rope is a one way trip to the sail becoming a furling jib. The alternative is to stretch the luff between two posts till ALL the wrinkles are out of the Dacron. If you can't remove the wrinkles, try releasing the tight hanks till they are free to rotate around the bolt rope. This ensures uniform spreading of the sail cloth along the bolt rope. With the luff stretched the body of the sail should lay flat. I stretched Panache's bolt rope with the hanks released and its the first time I saw the cloth flat. Don't be surprised if the luff extends a foot or so longer. The good thing is that a hanked luff is usually too long to fit the foil so it must be cut back. This was the case with my 150% genoa so it was suitable for conversion.
However, you should also look at reshaping the seams, leech and foot before you proceed. The following issues contribute to a smooth furled jib:
- As a rule of thumb, the foot roundness of a furling jib should be no more than 1.75-2% of the length of the foot.
- The leech hollow should be no more than 1-1.5% of the length of the leech.
- The clew height should be at chest height once rolled on the fore stay.
An alternative it to downsize a jib from a larger boat. This may look simple but is usually better handled by a sail maker who has the knowledge to assess the conversion and the experience to optimize the shape, condition and strength of the cut sail for an SJ23. North Sails advised me against this conversion as the draft would be too far aft for the final sail.
"The modified jib cannot go to weather without stalling. The boat will be forced to fall off to a close reach with larger heeling moment, causing drag. The cloth weight of a larger jib from a longer boat would likely be too heavy and the sail can't fly in light winds. New sail cloth is not only stronger but up to 30% lighter than same weights in 1999, resulting in better overall performance."
I don't have a heavy duty sewing machine and since my 110% and 150% jibs fit the furler and are still in good condition North Sails converted them to furling. I got amazing service in the winter when the loft was quiet. However, the luff tape of my modified jib was difficult to remove from the Scheafer sail feeder due to loose strands sticking outside the gate. This was resolved with a judicious application of epoxy to contain the loose strands in a shape that fit through the feeder.
Consider adding UV protection strips for the luff and foot. I chose a jib sleeve.
I added new tell tales to all jibs; starboard green high and port red low, separated vertically by about 3" so I can determine port from starboard in difficult light conditions. The bottom tell tales are visible from the helm.
Before you modify your factory jib, you should know that a full hoist 110% jib (blade) pulls way better than a modified factory jib. See Tech Tip F21.

PS: I decided to let the North Sails loft in Richmond, BC convert my jibs to furling after several discussions with their sail makers. The 110% jib was converted first as this luff was guaranteed to fit. The following year the 150% genoa was converted. Both sails are now totally wrinkle free and pull far better than when they were equipped with hanks. See Tech Tip F21. TOP

TYPICAL FURLING OPERATION - Every boat has a unique sequence of operation depicted by the requirements of the furler manufacturer and hardware on board. Study your furler operating manual for this. It is assumed the furler is equipped with a halyard retainer at the mast head to prevent a wrap. In general it goes as follows:

Unfurl the Jib from Storage
a - If equipped, lower and fan fold the jib sleeve into its bag.
b - Remove any safety retaining straps (Velcro) wrapped around the jib to maintain a snug wrap. (prevents accidental release).
c - Tighten the back stay adjuster to tension the forestay (Tech Tip F09). (makes furler turn easier).
d - Point the boat so the wind is forward of the beam. (makes sail release easier).
e - Release the furling control line from the cleat and gently pull the leeward sheet or let the wind unfurl the sail.
(keep light tension on the furling line so it rolls up evenly on the drum and doesn't pile up against the 4 stakes) .
If jib doesn't unfurl, lightly tug on the sheet to unfurl the sail. Wrap the sheet around the winch.
f - Set the tension on the jib halyard to match the wind strength. (tension can only be adjusted on an unfurled sail).
g - Smile you're sailing!
Reef the Jib
a - Do not tighten the halyard of a jib that is partially rolled. This pull can't tighten the luff due to the grip the jib has against the foil. The harder the wind blows the greater the grip. Instead, the pull transfers the rig load from the forestay to the furling extrusion. Try to visualize the halyard pulling up the swivel, sail, extrusion, the torque tube attached to the turnbuckle and finally, the deck fitting.
b - It is best to set the halyard tension while the jib is completely unfurled. Set it so the wrinkles are just flattened.
c - One time I was able to test the furling system in heavy wind using a 150% genoa. While I had no problem furling the jib to any size (130%, 110%, 80%) the shape of a 110% or smaller jib left a lot to be desired. Closed hauled I could not point as high. Reaching was OK. Next time I'm going to my storm jib. It would be much better if the side deck tracks were extended 2 ft further aft so the sheet car can be positioned for each sail size.

REEF SIZES of the 150% GENOA. It's too bad was there was no wind this day. The genoa would have looked better filled with wind. But it gives you the idea. The sheet lead should have been moved to the side deck track. This is always a problem when roller reefing a large sail. Later I extended the track in Tech Tip ?. To be fair, I have only once used this sail while reefed. This was an experiment.
FIRST REEF	SECOND REEF

Furl the Jib for Storage
a - Point the boat so the wind is forward of the beam.
b - Maintain slight tension on the jib halyard. (tension can only be adjusted on an unfurled jib).
c - Pull the furling line while letting the jib sheet slip through your hand. (This is a balancing act between the two lines to achieve a snug wrap so the wind doesn't beat the rolled sail to death).
Once the jib is rolled up with 2 wraps of the sheets around the jib, cleat the furling line.
d - Wrap a few safety straps (Velcro) around the jib.
If possible, set a clip through the drum to prevent accidental unfurling. (Only possible on a metal drum).
e - Release the back stay adjuster (Tech Tip F09). (relieves the strain on the standing rigging)
f - Tuck away the sheets and hoist the jib sleeve if you don't have a UV strip on the jib.
g - Time to BS with the crew in the pub.

Partial Hoist Jib - Ideally all furling jibs, regardless of size, are full hoist which means the swivel rests within 5" of the top of the foil as in the far right image. But if you convert the smaller Clark 110% hanked jib to furling it will result in a partial hoist jib with the swivel well below the 5" down from the top of the foil. (See X image at right). This could result in a nasty halyard wrap.
To deal with a partial hoist jib you have 3 choices:
1 - If the luff is just short of fitting the foil length add a pennant at the tack to raise the jib so the swivel is within 5" of the top.
2 - If the luff is quite a bit short of fitting the foil length the manufacturer's solution is to add a pennant at the head such that the swivel is within 5" of the top as shown at far right. However, this may result in a upper pennant wrap for which I have created a solution. (See Pennant Wrap).
3 - Its also OK to add a pennant to the top and bottom.

Upper Pennant Wrap Solved - If the swivel on a round foil is not keyed to the foil then the foil can rotate inside the swivel. With this configuration it is possible for the upper pennant of a partial hoist jib to wrap around the foil, resulting in an upper pennant wrap. The halyard above the swivel is just fine since it is retained by the halyard restrainer. This is the case with the Schaefer CF500 & CF700 furlers and likely others with a round foil. My solution is to insert a 10" length of Dacron luff tape to the top of the pennant, just below the swivel. Wrap the luff tape tightly around the top of the pennant (just below the swivel) and hand stitch the luff tape to the pennant as shown at left. Pay particular attention to the strength of the stitching at the top and bottom of the luff tape as the pennant must pull the tape up and down the foil without jamming. With the luff tape in place the round foil and the inner part of the swivel rotate together, preventing an upper pennant wrap. The combination shown at left works flawless. By the way, the round foil works perfectly fine with a full hoist jib.

1 - This photo of a Clark 110% working jib with a 3' pennant added above the head was lowered to just above head height for demonstration purpose.
2 - My jib sleeve occasionally snagged on the halyard bowline. Therefore the knot was replaced with a smooth stitch and wrap similar to the pennant at the head of the jib.

Spinnaker Halyard Wrap Solved - The spinnaker halyard block is mounted at the front of the mast head. This is an external halyard so both lines are stored at the side of the mast. They come off the block right beside the top of the foil. The problem is that occasionally the halyard leading off the front of the block gets snarled or wrapped around the foil, stopping the furler hard. This, despite the fact that the halyard is tensioned tight to prevent the wrap. So far I have released the wrap by unfurling the jib, then furling it again without doing anything else. But it is frustrating when it is urgent to douse the sail.

There are two possible fixes for this problem.

Separate the aft portion of the spinnaker halyard from the foil by directing it to the side of the mast through a metal eye strap, then down the mast as shown a right. This technique is similar to the furler jib halyard restrainer mounted at the front of the mast. The beauty is that it works while underway.
Flip both sides of the spinnaker halyard around a spreader end. This is easier to do at the dock but a lot more difficult while underway if you have to flip the lines into the wind; with the wind is easier.

2019 UPDATE - After installing roller furling on Panache I discovered that a loosely tensioned halyard clipped to the pulpit could easily get wrapped inside the top of a furled jib, stopping the furler hard when the halyard goes tight. This wrap is difficult to see from the foredeck. For this reason I now store only the spinnaker halyard to the pulpit and keep it very tight. The primary jib halyard is always clipped on the furler swivel. The spare jib halyard for the stay sail (Tech Tip F36) is pulled up the mast with a 1/8" messenger line to retrieve it. This has the advantage of reducing the weight aloft. The bulk of the halyard is coiled in the cockpit halyard bag. TOP

PROTECT JIB FROM UV DAMAGE (2018) - And finally you must consider UV protection for the furled jib since removing it from the foil each time you dock sort of defeats the purpose of having a furler! However, you should be familiar with this procedure for an emergency. You can choose between strips of UV fabric sewn along the leech and foot or use a jib sleeve. A jib without the extra weight of UV strips flies slightly better in light air. Since none of my jibs have a UV strip (having been converted from hank on) and I do a lot of light air sailing, I decided to upgrade the jib sleeve I acquired. A sleeve also protects against air pollution and keeps the sail dry. They are quite popular in Europe and are gradually appearing in North America.

At the time of this photo my sleeve shown at right was without the bottom tensioning strap that secures it to the deck. I didn't know how to configure that at the time. You can see it in figure 6 below.

A sleeve that hangs loose over a jib will flap in the wind like a flag, beating itself to oblivion, which is also hard on the jib. So I'm copying a design I saw in the Netherlands plus adding a few ideas of my own. Features are listed below:

SLEEVE CLOTH - The cloth of a high quality factory sleeve is usually silicone impregnated to slide over the sail with minimal friction. Panache's sleeve looks like Sunbrella and is lined with a slippery coating. I acquired it third hand.
HOIST - The sleeve is hoisted to above the jib by a spinnaker halyard clipped to a fabric loop sewn at the top of the sleeve. Similarly there is another adjustable strap sewn to the bottom that tensions the sleeve at the deck. Both are stitched to the front of the sleeve so the rest of the fabric hangs. It is important that the top strap is laid on the outside and the inside, then sewn to the cloth. This way it pulls the sleeve up parallel to the sail without gouging snagging the sail.
ZIPPER - The sleeve has a full length heavy duty YK zipper equipped with a light 3' long line attached to the zipper pull. The end of the line is temporarily looped over a tack horn on the deck so it automatically closes the zipper when the sleeve is hoisted out of the storage bag. The top of the sleeve has a flap that goes over the zipper to protect the sail cloth during the hoist and during storage against the furled sail. It keeps the zipper closed against the pull of the diagonal lacing lines.
BLOCKS - The Royal Marine's blocks are glued and sewn to the sleeve, one meter apart for the 9 meter length of the sleeve.
DIAGONAL LACING LINES - The two Dyneema lines zig zag down the front of the sleeve through Royal Marine proprietary blocks that afford minimal friction. When tightened, the 1/8" Dyneema lines grip the sleeve tight around the jib to prevent flapping. The free end of the lines go through a ring at the bottom and are tied there, then secured with a Velcro strap around the sleeve to prevent the knot working loose. The diagonal lines must be Dyneema for no stretch and to release easily when pulling the sleeve down. This part works so well that once I release the lines, the sleeve almost falls into the storage bag, there is that little friction. This is the advantage of a good sleeve over a poor one.
HOIST & STORAGE BAG - I hoist and retrieve the sleeve using a repurposed spinnaker turtle launching bag slung inside the pulpit. The bag is equipped with a wire ring to hold it open and 3 straps secure the ring to the pulpit. The opening of the bag is wide enough to easily fan fold the sleeve into it or to pull it out to cover the jib.

Panache Jib Sleeve e/w Diagonal Lacing Lines.

Fig 1, TOP - The Dyneema lacing lines loop through the SS ring captivated for strength in the top strap of the sleeve. The two bungee cords never did pull the Dyneema lines up to release the sleeve so I removed them.

Fig 2, TOP - After the zipper at the top of the sleeve is started, the flap is folded over and held by Velcro to protect the sail cloth. The hoist strap is now sewn to the inside and out to prevent snagging. Royal Marine block below.

Fig 3, BOTTOM - The repurposed "turtle bag" ready to accept the fan folded jib sleeve. I added 3 nylon straps with SS twist lock fasteners to temporarily secure the bag to the pulpit. They don't come loose.

Fig 4, BOTTOM - The "turtle bag" loaded with the jib sleeve ready for storage on the forward berth. The closed top contains the sleeve nicely when I drop it through the forward hatch.

For launching, it comes out perfectly to cover the jib. The best part is the zipper closing automatically as the sleeve is extracted.

Fig 5, MID - Notice how the lacing lines pucker the sleeve along the forestay. This is the very thing that supports the fabric from fluttering in the breeze.

Fig 6, BOTTOM - The bottom strap tensions the sleeve against the pull at the top. The Velcro strap ensures the knot does not come loose in a blow.

The spinnaker halyard is used to hoist the jib sleeve. The free end is secured to a cleat mounted on the front of the mast at a height where it doesn't snag the genoa sheets during a tack.

2018 - To date, this sleeve continues to outperform all other designs on the lake, staying snug and quiet gripping the jib during the storms. This surprises me, since a couple of storms were particularly vicious. All other sleeves suffered some damage with one jib shredded to pieces after the total failure of its loose sleeve. Now I've got people wanting to copy it. TOP

Return to Tech Tip Index. . . . . . . . . . . . . . . Have a Question?