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Go Back   SailNet Community > On Board > Gear & Maintenance
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  #1  
Old 06-13-2006
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Question Headsail design

Now I know that I could possibly get a lucid answer from the average sailmaker but it would be interesting to see the response from the forum.
When I was a lot younger we used to race with a foil on the forestay that had two tracks. Into the tracks went the bolt rope of the head sail and when you wanted to reduce or increase sail, you hoisted one in the second track then dropped the other. Americas Cup boats still do that so it couldn't have been all bad!!
The sails we used had a low-cut clew that had the foot of the sail running sort of parallel with the deck and the #1 would be about a 150% genoa running down to a storm jib at around #5.
Now for the question. When I changed to my first roller furler, I was irritated by the fact that I could never reach the jib sheet bowlines without furling the sail right out because when fully furled, the clew ended up halfway up the forestay. Minor problem but irritating nevertheless.
The bigger irritation is that whenever the wind gets unruly and the sail has to be furled, the "triangle" that is created by the diminishing sail also always ends up halfway up the forestay, reducing the draft by say, 50% but the heel by 25%. And I started to wonder about why the so-called "Yankee" high-cut clew became so popular. Whatever happened to the full-bodied sail that I knew as a kid? Why can't the sail furl at the bottom of the forestay keeping the pressure lower down and reducing heel?
With a mainsail boom furler, the reefing happens logically, bringing pressure down to the lower part of the rig. What went wrong with the headsail furler?
The two reasons I have heard in anecdotal chatter are that a) the high cut clew lifts the foot of the sail off the deck and improves leeward visibility and b) it stops the foot from being abraded by the top wire of the guard rail when you're not close-hauled. I can't think of another logical reason.
There has to be more to it than that.
Is there?
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Old 06-13-2006
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To make the headsail furl right along the foot of the sail, the geometry of the sail would be all wrong. To do that, the sail would have to be cut with the foot of the sail at a 90 degree angle to the headstay. The foot to headstay angle has to have an angle smaller than 90 degrees as the headstay angles back towards the mast and the foot roughly parallels the deck, except in the case of a high clew sail. So as the sail is rolled up, the foot of the sail slowly wraps higher and higher, as the sail is being brought in evenly at its top and bottom edges.

High-clew sails do several things. First, it does improve leeward visibility, and this is often important for a cruiser, who is sailing short-handed. Second, it reduces the chafe of the foot of the sail on the life lines, and reduces the sails tendency to catch on the lifelines when tacking or jibing. Third, it reduces the sails tendency to catch water when the boat is heeled.

BTW, most mainsail furling systems have to lower the main as they furl/reef the mainsail, as the foot of the mainsail is roughly perpendicular to the mast. If you roll the sail in either the horizontal (boom furling) or vertical (in-mast furling) planes, the area will move down and forward, as the mainsail is effectively a right triangle, and you're shortening on one of the two sides that are perpendicular to each other. On a headsail roller furler, you're rolling up the hypotenuse of a right triangle—not either of the shorter, perpendicular legs.
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Last edited by sailingdog; 06-13-2006 at 06:29 AM.
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Old 06-14-2006
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Thanks for an intelligent answer. The clew will obviously roll along a line that is at right angles to the forestay and, yes it will creep up the forestay. However. . .
I did a quick CAD calculation on a sail with the foot cut parallel to the deck and one cut 15 degrees up from there. The difference in the height of the clew fully furled is 1.4 metres on a 12 metre forestay. It grows from 2.9 metres (reachable standing on the pulpit) to 4.3 metres (out of reach).
And the furled triangle suffers the same malady.
However, you have answered my question to a large degree.
Thanks.
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Old 06-14-2006
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Glad to help. Being short, I have much the same problem with reaching the clew of the head sail when it is furled. Unfortunately, I can't see any real solution to it...other than the one I have, which is to have some very tall people crewing for me.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

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Old 06-14-2006
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The high clew that you describe is typical of a jib cut for cruising. Beyond the two issues mentioned above, for offshore cruising, a deck sweeper can be a serious problem when it comes to taking the full brunt of a wave over the bow and possible damaging the headstay or furler.

Those of us who are more performance oriented, and spend the majority of our sailing time doing coastal cruising, typically get our furler genoas cut more like the deck sweepers that you mention above. Essentially the foot of the genoa is cut with a lot of foot curve and leaves the foil nearly perpendicular to the forestay then sweeping up to the clew position.

In my opinion roller furling, whether for mainsails or jibs, has limited utility as a serious heavy weather tactic. Even with a padded luff, furled sails only retain an appropriate heavy sail when furled 15% or so and for short periods of time. When flown partially furled the leech slowly creeps towards the tack, powering up the sail just when a bladed sail is really needed.

I personally prefer to change sail to the appropriate sail for the conditions. My lighter condition sails are cut for a wide wind range, but focused on lighter air and more limited at the top end. My heavy weather sails are cut flatter than my larger genoas and with a slightly higher foot.

If you plan to go offshore with a furler, it is helpful to add safety straps to the luff of the jibs. Safety straps are strops that reach around the foil and hold the luff to the foil should the bolt rope pull out of the foil, or when the sail is being dropped. This should not slow the sail change since you have to go bald headed to make a sail change with a furler anyway.

Jeff
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Old 06-14-2006
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I'd agree with Jeff H that in heavy weather conditions, a roller-reefed sail is a less than ideal solution.

Jeff- Are the safety straps much like the snap hanks used on some hanked on jibs on smaller boats??
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
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—Cpt. Mal Reynolds, Serenity (edited)

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Old 06-14-2006
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The strops are made from short lengths of spectra strapping and they are attached to reinforced kringles along the luff. The ones that I have seen either have twist buttons or a locking snap of somekind.

During a sail change the old sail is dropped so that the strops are below the feeder and then the strops from the new sail are attached to the foil above the furler. A rigid, roller, type pre-feeder is used just below foil bolt rope slot. The strops need to be loose enough to pass over the prefeeder. This would work well with a short 'body bag' type sail bag with multiple attachment points at the rail.

Jeff

Last edited by Jeff_H; 06-14-2006 at 03:40 PM.
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Old 06-14-2006
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The strops are a great idea! They would also address one of the worst features of in-foil headsails which is the lack of attachment (other than the corners) during a hoist or douse. Shorthanded take-downs can get quite exciting in a serious breeze, and I once nearly broke a finger trying to prevent a sail being swept over the side when a part of it fell into the sea.
Absolutely agree that using a furler as a reef is a non-starter.

Last edited by Faster; 06-14-2006 at 02:20 PM.
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Thanks for the info on the straps Jeff. I'll have to talk to my sailmaker about them.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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