Jib Furler

Moderator: GreenLake

Endless Line Jib Furler

Postby hectoretc » Fri Dec 02, 2011 9:51 pm

This is an old discussion on Jib Furling, but the difference here is the product involved (still available from the supplied links but $50 more expensive) is an "endless line" furler .

1157
http://www.apsltd.com/Tree/d273000/e270845.asp

Am I correct that an endless line furler allows the jib to be deployed anywhere in it's range of roll-out and locked in place? That would seem to be an advantage over most of the other furlers that I've read about that are the single line type and more "all or nothing deployment".

Any significant disadvantage to this type of furler over single line types?
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Postby Alan » Fri Dec 02, 2011 11:03 pm

From my very limited experience (eight hours crewing in a Pearson 323 with a standard (non-endless) jib furler), I'd say that the standard type of furler isn't all or nothing.

We used the furler to reef the jib as the wind changed. As I understand it, using a furler to reef the jib isn't the best approach, since the luff of the sail ain't pretty (or aerodynamic) as it hits the wind, but it does work to shorten sail. You control the leech with the sheet as usual, changing the length of the sheet as needed.

Executive summary: Shorten sail, tug the furler line to roll the jib up; lengthen sail, tug the active sheet to unroll the jib.
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Postby GreenLake » Sat Dec 03, 2011 12:12 am

Alan, I think you got the essential right, here.

If letting out just a tiny bit of jib will balance your boat better when you are essentially only using the main, it might make a difference on a day where you're overpowered and just want to be able to sail home.

Normally, to get somewhat better results, a roller reef would have a padded luff, so the sail shape is somewhat less hopeless in the reefed state. I've only seen those on bigger boats.
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Postby jdubes » Sun Dec 04, 2011 11:45 pm

Does anyone have a picture of this specific furler setup on a DS? It seems like it would be difficult to get a good shape on the head sail.

http://www.apsltd.com/c-1071-rwo-endless-line-dinghy-furler.aspx
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Postby GreenLake » Mon Dec 05, 2011 12:56 am

Are you worried about headsail shape when the sail is fully unfurled? Why? I'd assume you'd use this with a sail that has an internal wire luff, which can be tensioned all the way. If that's the case, there should be no difference in sail shape.

What you can't expect is to roller-reef this thing and get anything spectacular.

Or am I missing something here?
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Postby jdubes » Mon Dec 05, 2011 8:05 pm

GreenLake wrote:Are you worried about headsail shape when the sail is fully unfurled?


Yes. It seems that with this type of Furler setup, it would be difficult to keep a good jib shape. Other Furler options where the setup retains a forestay, jib shape wouldn't be an ssue.
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Postby GreenLake » Mon Dec 05, 2011 8:14 pm

Why would that be? The (non-furling) jib I bought has an internal wire and can be tensioned to the point that the forestay will go slack, so that what defines the shape of the luff is entirely the halyard tension.

This was done in an effort to improve the performance of the jib, so why would this not work with such a setup?

I've sailed on other boats that had a similar setup without forestay and it worked fine there, so I'm curious whether there's some specific reason why this should not work.
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Postby Alan » Tue Dec 06, 2011 12:07 am

I've been mulling this over, not least because there's a Harken small-boat furler sitting in my box of shiny stuff waiting until I get some spare time to set it up.

Like GreenLake, I'm puzzled as to why a jib with a wire in the luff wouldn't do just as well (completely unfurled, and tensioned so the wire is keeping the luff straight) as an arrangement with a separate forestay. It seems to me that the forestay matters if you're going to hank the jib onto it, but you can't hank onto it and still use the furler.
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Postby jdubes » Wed Dec 07, 2011 8:28 am

Granted I haven't used this particular furler so this is just a hunch. But it seems to me that you could get a little jib sag where the hanks used to be connected to the Forestay. Thoughts?
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Postby Jett » Wed Dec 07, 2011 10:20 am

I notice in one of Roger's previous posts in this thread he chooses to clip the jib onto the forestay when racing, because of better sailshape. Though Greenlake's analysis makes sense about achieving maximum tension with the halyard alone on a jib with an internal wire, I still would think that the best luff shape would be maintained with the "two wire" approach (i.e., jib hanked to forestay and tight jib wire tension) in a stiff breeze.

Even though I no longer sail a DaySailer, I'm very interested in this topic and the continuous line furler for my ComPac 16. It has the right stemhead to set this up, and the jib is in the size ballpark of the DaySailer's.

So, I need a bit of clarification. Does an "endless line" for the furler simply mean a large loop (one that circles from the drum at the head to a turning block somewhere toward the stern)? If so, wouldn't the location of the knot to achieve the loop be critical, assuming it couldn't pass through the furler drum when furling or pulling out the jib with the sheets? Thoughts?
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Postby GreenLake » Wed Dec 07, 2011 11:33 am

I always imagined that one would use a splice rather than a knot.

My other boat has a furler, but it's not an endless one.
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Postby GreenLake » Wed Dec 07, 2011 11:45 am

Jett wrote:I notice in one of Roger's previous posts in this thread he chooses to clip the jib onto the forestay when racing, because of better sailshape. Though Greenlake's analysis makes sense about achieving maximum tension with the halyard alone on a jib with an internal wire, I still would think that the best luff shape would be maintained with the "two wire" approach (i.e., jib hanked to forestay and tight jib wire tension) in a stiff breeze.


What's preventing the sag is the tension, resiting sideways pressure. The maximum amount of overall tension has some upper limit, no matter how many wires, external or internal one uses. The reason for that is that the tension needs to be balanced by (swept back) shrouds. Once you increase forestay (+luff) tension too far, the mast will come forward.

On a jib with an internal luff wire, what you end up doing is tightening the halyard to the point where some, or even most, of the total tension is taken up by the luff wire and the forestay becomes slack. In some ways, it simply turns into insurance against sail/halyard failure. (Otherwise the mast can come down on such failure).

If you entirely replace the forestay, the entire tension will be on the luff wire, which will then resist sag just as well as the forestay.

Anyway, that would be my reasoning. There are sails that don't have a luff wire, and I would think that those cannot be used in a way that makes the halyard tension primary. With such a sail, you use the halyard to set the luff tension (that's tension on the cloth itself).

With an internal wire, there's usually a small line from a cringle on the sail cloth to set the luff tension. On my present jib, this line is pre-tied, so that if I tension the wire the proper amount, then the resulting luff tension should be OK. But it can be adjusted, if needed and could be made continuously adjustable if I cared.
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Postby Jett » Wed Dec 07, 2011 12:59 pm

Good reasoning on jib halyard tension/forestay issue. And on splicing the continuous furler line, too, though I fear the few times I've tried to splice old halyards, my results were about as bad as knots!

One more thing on the endless furler line...it seems there would have to be pretty good tension on that line, so that the furler drum would have enough friction applied to furl the jib. If so, that would make splicing a bit more challenging unless, of course, that furler drum comes apart (as do more traditional drums) so that running a line through that block could be done after some adjusting.
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Postby jdoorly » Wed Dec 07, 2011 8:08 pm

Continuous furlers do present a line management problem. The continuous line is usually hove through small blocks attached to lifeline stantions with a tensioning mechanism in the cockpit end.

I have 2 drum furlers mounted on a sprit. The jib furler line is lead along the port rail and present no problem. The UPS furler line is currently lead on top of the foredeck back to the starboard chainplate and does present a trip hazard as well as a hazard due to rolling under foot if you step on it. I plan to reroute the UPS line this winter.

I tend to sail with more sag on my forestay and halyards because of past owners overtensioning, evidence of which can be seen in the hogging of the shear near the chainplates. I suppose it is theoretically possible for me to reef, even without a solid stay on the furler but I would probably need to upgrade the furler line from 7/64 to 3/16 to take the strain, though I've never tried to reef it.
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