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us7070

Top-Down Furler - for asym's

32 posts in this topic

Got my new issue of Yachting world, and it has an article about furlers for free-flying sails - mostly code 0's, and gennakers.

 

There is a small section on something, relatively new, called a "top-down" furler, which they say is being used by race boats for asymmetrical spinnakers, and which they say will be making it's way to cruising boats.

 

I guess I though that the existing furlers for free-flying sails were being used for asym's...,

 

or maybe they were actually top-down furlers, and i didn't realize it...

 

or maybe the sails were actually gennakers, not real asym's, and i didn't realize it...

 

when does a gennaker become an asym - is there some AWA, below which the sail is a gennaker?

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Might "top-down" furling refer to furling along the foot of the sail; analogous to old-school slab-reefing jibs?

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IIRC from the article in TDS, developed for the 80' Beau Geste. You have a separate torsion furling cable which isn't in the luff of the sail. The tack is on a bearing, so it's free and doesn't rotate as you rotate the furling drum. As you furl, the torsion line turns and wraps the sail from the head to the foot.

 

Details here: http://news.futurefi...own_furling.pdf

 

 

 

This differs from Balmar Rollgen, where the kite rolls from the top and bottom at the same time.

 

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i was going to ask how it differed from the balmar device.

 

so, why is it better to roll an asym from the top, but it's better to furl a gennaker from the bottom?

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The gennaker furlers work just like a normal jib furler, theorectically spinning the top and bottom together. This only works if there is a luff rope of some sort built in to the sail, and requires some luff tension to work, so you end up with a 'gennaker' type sail that doesn't have a lot of area in the luff. The 'top-down' types have a luff 'stay' for lack of a better word, so the system allows you to have a loose luff, like a real downwind A-sail needs to have, and then gives you something to wrap it around. The actual hardware is pretty similar between the two.

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What do they use for the torsion furling cable? Anything special, or would just a large diameter braided polypropylene line work?

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It is a special rope designed for this job to resist twisting. Stretchy poly-anything would not cut it.

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The Balmar Rollgen does furl principally from the top. The top rolls earlier and tigher than the bottom. BTW, I have one and it's for sale if anyone is interested. It turns out I don't have sufficient space between my furled jib and the furled spinnaker. Send me a PM.

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Since the head and tack are fixed with the furling line, how do you adjust shape?

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Since the head and tack are fixed with the furling line, how do you adjust shape?

 

If I heard correctly the tension line, while rigid enough to be furled, is still succeptable to halyard tension. This is why halyard tension is so important when you're flying Code Zero's because without it the shape of the sail is going to be all wrong.

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Since the head and tack are fixed with the furling line, how do you adjust shape?

 

If I heard correctly the tension line, while rigid enough to be furled, is still succeptable to halyard tension. This is why halyard tension is so important when you're flying Code Zero's because without it the shape of the sail is going to be all wrong.

 

Guys

 

When you are talking top down furling, you need to forget what you know about traditional Code 0's and even A3 type sails with an integrated Luff cable.

 

Top down furling does exactly what it says. It's a torsioal cable, independent of the sail. When you start your furl, whether with a continuous furling line or a hydraulic furling unit, the cable transfers the torque all the way to the head swivel, where the sail is lashed and because the tack is not connected to this set up, it starts furling the sail from the top down. Some manufactures such as KZ marine and Karver actually build dedicated furling units for this. Its similar to their code sail furlers except that the tack can freely rotate.

 

This system is finding a foot hold in the superyacht market as it effectively makes the 'bucket's', which can get jammed and take a cast of thousands to opperate it, redundant.

 

There are a couple of Vids online:

 

 

 

http://riggingnews.b...4/its-wrap.html

 

http://riggingnews.b...ts-wrap-ii.html

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Here's a link to a video with a good explanation of the system in use on something a little less exotic than Beau Geste or a Swan 112.

 

We are just taking delivery on one of these for a J109 and will report in a few weeks after some use.

 

My link

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The main difference between a regular Asymmetrical spinnaker furler and the Karver KSF Furler is that there is no small line that connects the luff of the sail to the anti-torsion rope. The regular asymmetrical spinnaker furler rolls the sail from the upper third (or around that area); the Karver KSF rolls the sail from the top down. From Karver KSF product description:

 

"The KSF Furler includes all the advantages of the KF line, but incorporates an independent swivel on the top of the drum that enables the sail to furl from the top to the bottom. It is now possible to furl the Asym from the cockpit for more safety and convenience when cruising. This is also a weapon for racers that can hold their asym closer to the mark and in worst weather conditions.

 

The anti torsion line is independent from the luff. The tack of the asymmetrical is attached to an independent swivel on the top of the furling drum while the head of the spinnaker is lashed to a lashing thimble. When furling, the spinnaker starts to furl from the head and continues down to bottom, hence the term “Top Down Furler”. The system is already approved by Maxi Yachts and do not need to have the spinnaker retrofitted."

 

Check here for load capacity and sailboat size selection: Karver KSF Asymmetrical Spinnaker Furler

KARKSF_F.jpg

 

Note about Gennaker vs.Asymmetrical Spinnaker:

 

"when does a gennaker become an asym - is there some AWA, below which the sail is a gennaker? "

 

We consider a "gennaker" to be sort of a generic name for asymmetrical offwind sails. IN a general way, we refer to them by AWA:

50 - 80: Code Zero (laminate sail with integral luff rope)

80 - 110: Gennaker or Close Reaching Asymmetrical Spinnaker (nylon sail)

110 - 140: Asymmetrical Spinnaker (nylon sail)

 

Best,

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Anybody can douse in those conditions - can it handle heavy air?

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Anybody can douse in those conditions - can it handle heavy air?

Abu Dab was/is using this system for their fractional runners.

My thought was to make the luff of the heavy air kites about 12" short so that you could unfurl with the 2:1 tackline tight, then ease the tack up for sailing, then tension again for furling.

A short luff can also make your heavier air kites reach a little better by allowing you to tension the luff which frees the leach a bit.

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Have used the Karver top down on a class 40 in 35kts+. Works like a dream.

 

Have used other systems but none are as good as Karver IMHO.

 

If I remember correctly the whole top down concept was originally developed by Karver and Allspars

 

 

 

Anybody can douse in those conditions - can it handle heavy air?

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the torsion line is the key to the system

check my buddy John from colligo marine

 

tell him I send you ... lol

 

Thor

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How's the top-down affect the life span of the sail?

 

Especially in a blow it tends to get very tight at the top and the material is taking a lot of the tension (in a direction not intended by the designer)?

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We have quite a few Asymmetric furling systems out there now in several different sizes. All top down style. I would say similar to Karver's but really theirs is similar to ours...

 

Here is what we have learned about top down style furling for asymmetrics:

 

1. A good torque line is essential. A twisty torque line will wind the sail up while twisted, then when the torque of the drive line is released the line will twist the sail up, often into a mess that demands lowering the hole system and untwisting the sail by hand.

 

2. Asymms seem to roll up easier in higher winds (might be a limit to this!) as we think this keeps the sail away from the torque line longer, which is key to rolling the sail up correctly.

 

3. Keep the clue from rolling in until the last 1/4 of the sail or so is rolled in. The clue rolling in too early can make for a mess when unfurling the sail.

 

4. Good tension on the system (halyard) helps but not essential if you have a good torque line.

 

5. Keep good tension on the clue when unfurling as the lower end of the sail can get sucked back into the lower end of the system when unfurling, especially in light winds. This can cause issues.

 

6. When furling in it helps to keep the sheets together as they are rolled around the sail. If you let these go in separately it sometimes causes issues when unfurling.

 

7. An existing sail that is cut for a full hoist sometimes causes issues as the hoist length is now shorter by the distance of the furler drive end and the swivel, making for a curvier luff. The straighter the luff it seems the better the sail furls in. Some existing sails might not work if the luff ends up being too curvy.

 

As with sleeves there is a learning curve with a top down style spinnaker furler. One thing I like about our systems is that they seem to work better as the winds go up. The high torque line that we have works great even in higher winds. These systems work good now but all of us manufacturers are still on a learning curve here so stay tuned for more as we attempt to perfect this great method of handling a light air headsail.

 

Best Regards,

 

John Franta, Colligo Marine

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Dear all,

 

We have just developed a new Top Down Furler at Profurl : The SPINEX.

 

We are posting lots of news and videos online : http://www.facebook.com/pages/Profurl-America/401156926587196

LIKE it if you want to keep in touch.

Press release : http://riggingnews.blogspot.com/2012/08/spin-me-right-round.html

 

Feel free to ask questions.

Regards,

 

Clément Leflot, Development Engineer, Wichard - Profurl

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Is this system what they are running on the AC 45's? Seems like it- crazy cool function makes me think that there are some cool sail options possible for short handed mono's

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Is this system what they are running on the AC 45's? Seems like it- crazy cool function makes me think that there are some cool sail options possible for short handed mono's

 

Hello U20guy2,

 

I think I understand why you think they are the same system as the AC45s: because the hoist / unfurling is so easy and quick just like on our SPINEX videos that you apparently saw on facebook or youtube.

However, it is not exactly the same systems but could be... let me explain.

 

In the flying sail furlers world, there are 3 types of sails that can be furled :

 

1st - The "Code 0" : which has a straight luff and for which the torque rope (or furling textile cable) runs through the luff in the sail pocket: like on the AC45s.

2nd - The "Staysail" : also a straight luff and more and more popular for removable staysail systems.

3rd - The "Asymmetrical Spinnaker" : which has a loose luff, which means that the luff is separated from the torque rope.

https://plus.google.com/photos/105849540239944113160/albums/5782808962593925169?authkey=CIXxk4zSrsu4lAE

 

Our new SPINEX concerns the 3rd sail and is designed to suit your existing Asymmetrical Spinnaker.

However, the SPINEX is a complete package that includes the NEX: which is just the flying sail furling unit and can be used for the 1st (Code 0) and the 2nd sail (Staysail).

 

So you are right, the are some cool sail options : One SPINEX can be plugged to 3 sails with an easy quick sail attachment:

 

The SPINEX Kit is available if you already have an NEX.

 

Clément

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Fast multihulls like AC45s don't have asymmetrical spinnaker because they go too fast and therefore their Apparent Wind Angles are low :

 

Generally speaking : but depends a lot on your sail shape

 

- Code 0 (or similar straight luff down wind sails) : AWA = 50 to 120°

- Asymmetrical Spinnaker (loose luff) : AWA = 70 to 160° : depends a lot on your sail shape

https://plus.google.com/photos/105849540239944113160/albums/5782808962593925169?authkey=CIXxk4zSrsu4lAE

 

Having the two sails gives you great performance gain.

Having a furled removable staysail would also bring a lot more comfort in strong breeze: stay in the cockpit all the time.

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Fast multihulls like AC45s don't have asymmetrical spinnaker because they go too fast and therefore their Apparent Wind Angles are low :

 

Generally speaking : but depends a lot on your sail shape

 

- Code 0 (or similar straight luff down wind sails) : AWA = 50 to 120°

- Asymmetrical Spinnaker (loose luff) : AWA = 70 to 160° : depends a lot on your sail shape

https://plus.google....CIXxk4zSrsu4lAE

 

Having the two sails gives you great performance gain.

Having a furled removable staysail would also bring a lot more comfort in strong breeze: stay in the cockpit all the time.

 

I know this - heck even on the U20 there were times a code zero would have been fantastic in SF winds given the boat speeds we could do. However if your short handed or single handed and on a mono that can plane - this furler system would in effect open up a wider range of solo or short handed sailor sail options that remain easy to handle enabling a solo sailor or double handed boat to carry more sail when they might have simply gone short on sail due to the lack of easily managed sail options etc.

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My idea here is that some of these newer boats comming out that are laid out for short handed efforts are of great interest to me for example the Pogo 10.5 seems like a fantastic combination for both fun family sailing in SF bay - even delta cruising with the lifting keel option. Yet dad or even dad and mom could do SSS events on it - pair up some well designed down wind sail options with this new furler technology and it seems like boats like the Pogo 10.5 would be a blast for the short hander to sail and race. Very different than dealing with an older 34footer and a symmetric kite or even a asymmetric on a prod etc.

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I'll probably be using one of these next season, and have just had a 2A designed with a bit shorter luff so I can tension it slightly before rolling it up.

 

The bugaboo right now is the torsion rope, especially for smaller boats. I'm told the smaller-sized torsion ropes are twisting too much. The roller-ball deal above looks interesting but seems like a lot more weight and windage. Racing solo, you may not be able to get the thing on deck until awhile after rounding the leeward mark.

 

I've used a Code Zero on a Facnor furler successfully for several years and just put a NDPO 3A/5A on that furler for around here. My goal is to be able to "peel" between the reacher and runner (with both on furlers).

 

I'd like to hear more about reliable torsion ropes (41 feet long for a 93 s/m 2A).

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Bump.

 

Anyone using one of these successfully on a 30-35 footer? Whose torsion rope is working?

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Hello BobJ,

 

Part of our development process was to test different Torsion Ropes.

We tested the Torsion Ropes over a 30ft length.

We selected the best supplier for our SPINEX package and we are very happy with its performance.

 

It is important to always furl in the same direction : the cable will develop a Torsional memory and become even more efficient over time.

The torsional performance also depends on how you use your sail:

- If you ease the sheet completely before furling, the sail would immediately start furling.

- If you keep some tension on the sheet, either to have a very tight furl or to pre-load some torque on the cable, you would have to turn a very maximum of 10 turns before you reach the effect point when the sail starts furling.

 

Please follow us on Facebook as we will post new videos very soon.

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No dis to the Facnor, ProFurl etc geezers but JFranta at Colligo has the pimpest looking furling gear. The multihullists seem to like their stuff because it's compact, lgiht and is reported to work well. Plus he answers really stupid questions (personal experience). Quite a few smaller Farriers are using his torque ropes and they report good results.

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