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Furling Unit for Assymetrical


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#1 Captain John

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Posted 10 March 2012 - 12:03 AM

One of my members asked about furling units for asymmetrical spinnakers or gennakers and whether they will handle winds up to 15 knots. He has a Jeanneau SO33i.. He referred to a unit called a rollgen ( also mentioned code-1 or code-0) that he saw in a demo. This unit installs on the pulpit. That seems like a pretty weak attachment point vs. the stemhead fitting. Any advice / recommendations would be welcome.

#2 Estar

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Posted 10 March 2012 - 01:10 AM

One of my members asked about furling units for asymmetrical spinnakers or gennakers and whether they will handle winds up to 15 knots. He has a Jeanneau SO33i.. He referred to a unit called a rollgen ( also mentioned code-1 or code-0) that he saw in a demo. This unit installs on the pulpit. That seems like a pretty weak attachment point vs. the stemhead fitting. Any advice / recommendations would be welcome.


Complex question, but the short answer is:

There are two basic types of furlers here - lets call them: (a) rope luff furlers (Facnor and karver being two big brands) with have an anti-torque rope built into their luffs, the sails fly with a tight luff, and then furl around that ant-torque rope, and ( b ) top down furlers (rollgen is one) where the sail can have a fuller luff, which can sail deeper angles, and there is a separate anti-torque rope that when furler will wrap the sail starting from the head.

The trade-off is that the first type (rope luff) furler better and more reliably but they compromise the shape of a deep angle sail (because the luff can not rotate).

A code zero is a flat cut, mostly close reaching sail, usually run with the rope luff furling systems.

A code would would be a deeper sail, for broad reaching and might be flown from either type of system.

You would not want to tack any of these from the pulpit, unless it was specially reinforced. The tack, especially on a code zero, will take significant loads.

There is some discussion and difference of opinion, but here is one chart that shows the wind angles and strengths for flying these sails.

Attached File  quantum C0.JPG   123.44K   227 downloads

#3 Ishmael

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Posted 10 March 2012 - 01:20 AM

I know several boats with the Rollgen system, a C&C 32, a 33-1 and a 37, and an Ontario 32. Most have them tacking to the pulpit which is reinforced down to the bow. It is strictly a light-air sail. The spin/gen has to be cut flat to furl anywhere near well, but it's an easy sail to get flying.

#4 jackdaw

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Posted 10 March 2012 - 05:33 AM

Good stuff so far. A problem with aspins on a lot of boats is the bow area was not designed for the tack of an asymmetric. Even on non-rolling sails, the luff and/or tack line can foul in the bow pulpit. Take my word for it, I'm expert at tearing off bow lights. Furlers (on code 0s in particular) are worse because the luff need to be tight and that means a straight shot from the masthead fitting to the tack attachment. Often the pulpit gets in the way. The cheeszy way out is to mount the tack on the pulpit. For Kestrel we are adding a small prod mounted to the beefy anchor roller base. Not lots of extension but just to get clear of the bow. The dyneema strop takes most of the load.

And as Estar nice pic shows, you wanna have the 0 stowed way before you see 15 knots.


Posted Image

#5 Overbored

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Posted 10 March 2012 - 06:10 AM

Facnor makes a spinnaker fuler that will work on asymmetrical spinnaker. it has a torque rope that is not part of the sail and there is a small line atached to the center of the luff and around the torque rope. when you furl the torque rope starts to take up the center of the sail first. I have one on my 4A. works best on the less full sails and takes a bit of coordination between the fuler and sheet handlers. vidio on Facnor web site
http://www.facnor.co...ers/default.asp

#6 Innocent Bystander

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Posted 10 March 2012 - 12:05 PM

Good stuff so far. A problem with aspins on a lot of boats is the bow area was not designed for the tack of an asymmetric. Even on non-rolling sails, the luff and/or tack line can foul in the bow pulpit. Take my word for it, I'm expert at tearing off bow lights. Furlers (on code 0s in particular) are worse because the luff need to be tight and that means a straight shot from the masthead fitting to the tack attachment. Often the pulpit gets in the way. The cheeszy way out is to mount the tack on the pulpit. For Kestrel we are adding a small prod mounted to the beefy anchor roller base. Not lots of extension but just to get clear of the bow. The dyneema strop takes most of the load.

And as Estar nice pic shows, you wanna have the 0 stowed way before you see 15 knots.


Posted Image


Nice setup Jackdaw. Is the ring welded to the stem fitting or to the lower fastener?

#7 Joli

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Posted 10 March 2012 - 01:49 PM

Evans, do you fly mast head or frac kites? Do you use the assy furler? I've heard there can be "issues" for larger boats.


One of my members asked about furling units for asymmetrical spinnakers or gennakers and whether they will handle winds up to 15 knots. He has a Jeanneau SO33i.. He referred to a unit called a rollgen ( also mentioned code-1 or code-0) that he saw in a demo. This unit installs on the pulpit. That seems like a pretty weak attachment point vs. the stemhead fitting. Any advice / recommendations would be welcome.


Complex question, but the short answer is:

There are two basic types of furlers here - lets call them: (a) rope luff furlers (Facnor and karver being two big brands) with have an anti-torque rope built into their luffs, the sails fly with a tight luff, and then furl around that ant-torque rope, and ( b ) top down furlers (rollgen is one) where the sail can have a fuller luff, which can sail deeper angles, and there is a separate anti-torque rope that when furler will wrap the sail starting from the head.

The trade-off is that the first type (rope luff) furler better and more reliably but they compromise the shape of a deep angle sail (because the luff can not rotate).

A code zero is a flat cut, mostly close reaching sail, usually run with the rope luff furling systems.

A code would would be a deeper sail, for broad reaching and might be flown from either type of system.

You would not want to tack any of these from the pulpit, unless it was specially reinforced. The tack, especially on a code zero, will take significant loads.

There is some discussion and difference of opinion, but here is one chart that shows the wind angles and strengths for flying these sails.

Attached File  quantum C0.JPG   123.44K   227 downloads



#8 jackdaw

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Posted 10 March 2012 - 02:02 PM


Good stuff so far. A problem with aspins on a lot of boats is the bow area was not designed for the tack of an asymmetric. Even on non-rolling sails, the luff and/or tack line can foul in the bow pulpit. Take my word for it, I'm expert at tearing off bow lights. Furlers (on code 0s in particular) are worse because the luff need to be tight and that means a straight shot from the masthead fitting to the tack attachment. Often the pulpit gets in the way. The cheeszy way out is to mount the tack on the pulpit. For Kestrel we are adding a small prod mounted to the beefy anchor roller base. Not lots of extension but just to get clear of the bow. The dyneema strop takes most of the load.


Nice setup Jackdaw. Is the ring welded to the stem fitting or to the lower fastener?


It's on the lower fastener. The original was removed and replaced with a new one with a larger head for more surface area. The rings was welded to that. I figure it is the weakest part of the chain, but you might have to pick the boat out of the water by its nose to have it break.

This is mounted to a 36.7 that the dealer in Diego showed us because he knew we where interested. I'm having one like it fabbed locally, but I have the details of the guy who made this one.

#9 Captain John

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Posted 10 March 2012 - 02:12 PM

Great info from all you guys. Thanks a million - J

#10 Innocent Bystander

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Posted 10 March 2012 - 02:20 PM



Good stuff so far. A problem with aspins on a lot of boats is the bow area was not designed for the tack of an asymmetric. Even on non-rolling sails, the luff and/or tack line can foul in the bow pulpit. Take my word for it, I'm expert at tearing off bow lights. Furlers (on code 0s in particular) are worse because the luff need to be tight and that means a straight shot from the masthead fitting to the tack attachment. Often the pulpit gets in the way. The cheeszy way out is to mount the tack on the pulpit. For Kestrel we are adding a small prod mounted to the beefy anchor roller base. Not lots of extension but just to get clear of the bow. The dyneema strop takes most of the load.


Nice setup Jackdaw. Is the ring welded to the stem fitting or to the lower fastener?


It's on the lower fastener. The original was removed and replaced with a new one with a larger head for more surface area. The rings was welded to that. I figure it is the weakest part of the chain, but you might have to pick the boat out of the water by its nose to have it break.

This is mounted to a 36.7 that the dealer in Diego showed us because he knew we where interested. I'm having one like it fabbed locally, but I have the details of the guy who made this one.


I like it. There is an elegance in simple solutions.

#11 Nicolas Karver US

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Posted 15 March 2012 - 03:47 PM

Hi all,



To provide further information on Karver furling unit, there are two types available now. As Estar mentioned, one type is to furl sail that have a straight luff (Code sail type, staysail, Straight luff Gennaker ). With that type of sail, the anti-torsion cable requires to furl the sail is built into the luff. This year, Karver innovated with a features that enables to lock the drum. That way, one can avoid the inconvenient in having the sail unfurling accidently.


Attached File  Emmagasineur KF.jpg   560.2K   8 downloads

Karver launched last year a furler for Asymetrical spinnaker that furl the sail from the Top to the bottom because of the shape of an asym. In that case, the anti torsion cable is independent from the luff of the sail. The head of the spinnaker is attached with a lashing to a thimble that plugs into the top swivel. The tack is attached to an independent swivel on the top of the drum. When furling, the head will furl first as the tack is independent from the furling drum. The critical point is to have enough tension in the anti torsion cable when you furl/unfurl the sail.

Attached File  KSF2.jpg   317.98K   7 downloads

It is important to note that the system doesn't require the sail to be retrofitted. Thus, an old asym can be easily installed on such a system. Also, the system can be used with other types of sail (Code 0, Staysail, ). One could have one furler for the full inventory of flying sails.



We have used the system on A2 runners and it worked pretty well. Here is the link of a video shot in October on a Class 40 showing the system: http://www.youtube.c...Q3TD_QSkt_k7TfY=



We'll have another one online shortly showing the system on a J105.



Please let me know if I can provide with more info. You can also find more information online at http://karver-system...m/KarverEng.pdf




I hope this help.

Nicolas

#12 Overbored

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Posted 15 March 2012 - 05:44 PM

Nicolas, I do like the idea of the top done furling. I will have to try that with my Facnor that is on my A4. the Facnor has the center furling cord and sometime if you are not very careful the spinnaker will get a reverse rap and it will not unfurl the next time we use it. I am planning to get a new furler for the code 0 and maybe use it on the new A2. the difference I see in the Karver is that you can not install the furling line with the furler attached to the sail and on the Facnor you can. I was looking at the Karver size charts and there are no sail area listing on the charts, just load ratings so it is hard to determine the correct size I would need. I have a Soverel 33 with a j 105 sprit and a 1200 sq ft kite almost the same as a 105 kite

#13 Estar

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Posted 15 March 2012 - 06:05 PM

Evans, do you fly mast head or frac kites? Do you use the assy furler? I've heard there can be "issues" for larger boats.


J, sorry, did not previously see your question. Our light air sails are all masthead. I figure we might as get them up as high as possible. We use a facnor on our zero (which works great), but have been using socks on our deeper sails. I am not a great fan of the socks and will switch in a minute to the top down furlers as soon as I hear someone first hand really positive on them, but so far the messages I have been getting has been mixed.

#14 MR.CLEAN

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Posted 15 March 2012 - 06:12 PM

Here's the 105 video Nicholas referred to above.



#15 Beau.Vrolyk

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Posted 15 March 2012 - 06:36 PM

Capt. John,

One of the VERY FEW advantages to an old school boat is that there's something way out in front of the jib-stay to attach the Code-0 tack to. In the picture below, the Asymmetrical Chutes and the Code-0 tack on the ring on the tip of the bow, the jibs now run on hanks on the jib stay you can see on the right. As Estar said, you want to have a bit of separation between either the head or the tack of these sails if you're going to furl them. In our case, it was much better to move the tack point forward than modify the rig to move the halyard up. (Although I'd rather have the sail up higher or do both.)

With respect to loads, we figure our Code-0 has about 5,000 lbs of halyard tension and when the boat pounds that number could go up to twice that dynamically. As a result, it doesn't seem to me that a pulpit would be the right tack point unless you're using a much more stretchy (nylon) sail. Code-0 sails are almost all made of spectra or some other non-stretch stuff, like a genoa. Of course one could runs spectra line from the tack point on the pulpit down to the bow, provided that it was in-line with the load.

I suppose you could think of the long overhang on S'agapo as a really large and heavy sprit. :unsure:

BV

Posted Image

#16 Beau.Vrolyk

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Posted 15 March 2012 - 06:38 PM

For general information on Furlers, and a discussion on the differences between things like Code-0s and Asymmetrical Chutes, have a look at the Ronstan web page here.

BV

#17 Nicolas Karver US

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Posted 15 March 2012 - 08:40 PM

Nicolas, I do like the idea of the top done furling. I will have to try that with my Facnor that is on my A4. the Facnor has the center furling cord and sometime if you are not very careful the spinnaker will get a reverse rap and it will not unfurl the next time we use it. I am planning to get a new furler for the code 0 and maybe use it on the new A2. the difference I see in the Karver is that you can not install the furling line with the furler attached to the sail and on the Facnor you can. I was looking at the Karver size charts and there are no sail area listing on the charts, just load ratings so it is hard to determine the correct size I would need. I have a Soverel 33 with a j 105 sprit and a 1200 sq ft kite almost the same as a 105 kite


Karver spinnaker furler will differentiate in two ways from Facnor ones. First, there is no need to retrofit or get a line in the middle of the anti -torsion stay to help the sail furling. Second, one furler can do all as a standard. Facnor offers the solution to have special thimble as an option, which means you need to anticipate that you will use the furler with several sails when buying the furler. With Karver, you can first use the furler on an Asym and if in a few years, you'd like to invest on a Code sail, you can still use the same unit.

The furling line can be install with the furler attached to the sail. The notch on the drum makes it easy and possible to install it either with the furler attached to the sail or with the furler attached to the deck. What you cannot do is intalling it with the furler attached to both the sail and the deck at the same time. Though, as far as I know, this is not possible on any continuous line furler at this time.

Attached File  Engaging the loop line.jpg   66.97K   53 downloads


This type of furler can be used on masthead and fractional rig as long as there is enough clearance with the forestay to enable the sail to furl on the top. Clearance and tension in the anti-torsion cable are key points as well as the quality of the anti-torsion stay. One turn on the drum should result in one turn on the top swivel.

For a boat of your size, we recommend the use of a KSF2 which is the same unit than the one we used on the video posted by Mr. Clean. With this model, you will also be able to use it on a code sail. Recommendation on furlers will depend on the type of sail, sail area, type of boat and weight of the boat as well as the program of the boat. for any question / recommendation, please feel free to contact Karver at contact@karver-systems.com.

Please let me know if I can bring any more insight on the products.

Nicolas

#18 Overbored

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Posted 16 March 2012 - 05:01 AM

I understand how you get the furler line on from the top but have not seen how you get it on if the furler is attached to the sail only ( From the bottom ) . I have been keeping the furler in the bag with the sail. we attach the furler line and the tack line and pull to the end of the sprit as we hoist.

#19 jfranta

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Posted 16 March 2012 - 02:45 PM

We have done some R&D on top down style spinnaker furlers as we now have one for sale and are working on some other sizes. See the posts on Jailbreak in the multihulls forum. Some assyms that are too full will just not roll on any top down style furler as there is just too much to roll up. You end up with bits and pieces of the sail sticking out and this can cause issues. This is severely complicated if you have a twisty torque rope. A torque rope that twists will roll the sail in when the line is twisted then release the tension and the light sail material gets all mucked up, then sail deployment is oftentimes impossible. Having said that we have found that most assyms. from MP to flat cut will work fine as long as you have a good torque rope. We have what I consider the best torque rope out there and it does not need much tension at all to roll the sail in cleanly, which is essential for a good deployment.

John Franta, Colligo Marine

One of my members asked about furling units for asymmetrical spinnakers or gennakers and whether they will handle winds up to 15 knots. He has a Jeanneau SO33i.. He referred to a unit called a rollgen ( also mentioned code-1 or code-0) that he saw in a demo. This unit installs on the pulpit. That seems like a pretty weak attachment point vs. the stemhead fitting. Any advice / recommendations would be welcome.



#20 Foolish

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Posted 16 March 2012 - 07:39 PM

I have two questions about the Karver spinnaker furler while singlehanding and I'd love to get responses from someone with experience with them.

1. As I've emphasized in my book and proved again to myself last weekend in 30 knots, it is vital when launching the chute that the sheet be very loose so that the spinnaker does not catch the wind until the skipper has his tiller in hand. But the furler, by design, has the sheet tight during the entire unrolling process. Are we looking for trouble?

2. Is it necessary to steer downwind when rolling it in? Can it be rolled on a reach under pressure?

#21 Overbored

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Posted 17 March 2012 - 02:15 AM

mine is not Karver but has the same type of swivel on the tack. on my 2A I leave the sheet alone untill I unroll the kite with the furling line not by pulling on the sheets so the sheet is loose until I want to harden it up
mine rolls up a lot easier if you keep a small tension on the sheet to prevent an over rap but not the pressure of a full sail

#22 Estar

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Posted 17 March 2012 - 10:29 AM

30 knots . . . when launching the chute . . . Are we looking for trouble?


Yes!

#23 Foolish

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Posted 18 March 2012 - 04:11 PM

One more question. Can the entire unit be taken down quickly with the halyard, in case of emergency? I'm referring to the situation where I can't aim downwind to furl the chute because of an island in the way.

#24 Overbored

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Posted 18 March 2012 - 09:21 PM

Yes they can, but just how fast do the islands in you area jump out in front of you, in my area they pretty much don't move around much

#25 Trevor B

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Posted 19 March 2012 - 02:15 AM

I noticed that the VO-70 Abu Dhabi has top down curlers for their offshore spinnakers. It looked like it worked well for a reachy spinnaker.
All the other boats have straight luff kites that look like big reaching jibs with a bit of roach on the leech.

#26 zzrider

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Posted 09 August 2012 - 10:15 AM

This type of furler can be used on masthead and fractional rig as long as there is enough clearance with the forestay to enable the sail to furl on the top. Clearance and tension in the anti-torsion cable are key points as well as the quality of the anti-torsion stay. One turn on the drum should result in one turn on the top swivel.
Nicolas


Ah yes - what about this bit regarding use of such a furler on a masthead rig? On my last boat, the jib halyard sheaves were right at the very top - I can't imagine any way a spinnaker furler would have room for its swivel. What about a modification to the masthead to add a short crane projecting forward to which the spinnaker swivel could be hoisted, clear of the jib swivel?

(Edit: Sorry if this is an incredibly dumb question - never really did much with spinnakers, which is why the apparent simplicity of these furler systems appeals to me)

#27 Ishmael

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Posted 09 August 2012 - 02:54 PM


This type of furler can be used on masthead and fractional rig as long as there is enough clearance with the forestay to enable the sail to furl on the top. Clearance and tension in the anti-torsion cable are key points as well as the quality of the anti-torsion stay. One turn on the drum should result in one turn on the top swivel.
Nicolas


Ah yes - what about this bit regarding use of such a furler on a masthead rig? On my last boat, the jib halyard sheaves were right at the very top - I can't imagine any way a spinnaker furler would have room for its swivel. What about a modification to the masthead to add a short crane projecting forward to which the spinnaker swivel could be hoisted, clear of the jib swivel?

(Edit: Sorry if this is an incredibly dumb question - never really did much with spinnakers, which is why the apparent simplicity of these furler systems appeals to me)


Not a dumb question, adding a crane is exactly what happens when the furling units are installed. The two I have seen both project a good 6-8 inches from the masthead.

#28 zzrider

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Posted 09 August 2012 - 04:21 PM

Perfect, thanks Ishmael!

#29 rclouise

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Posted 13 August 2012 - 12:03 AM

Thank you all for all the info. I was never sure exactly how an asy furlor worked before this thread. We are getting the Fancor AFX 4500 for the new boat. Looking forward to using it instead of a snuffer.

#30 cap10ed

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Posted 14 August 2012 - 01:33 AM

Just when you thought there was nothing new under the sun. Thanks Clean I have been educated. Sharing with other cruisers as we speak.Posted Image



Here's the 105 video Nicholas referred to above.









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