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Old 11-03-2010, 11:56   #121
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Originally Posted by keelbolts View Post
As I stated, it is simply my belief that roller furlers are not good in heavy weather. One needs only to look around any marina to see that most people don't share my belief. I've seen them break out numerous times just sitting at the pier in a blow. On one occasion, it took down the rig with it. I know the Pardeys are not big fans either. When I saw them they had many photos & stories of furlers gone wild. I did a Bermuda trip with a cutter on which all sails were roller furling. It was pretty handy when the weather was nice, but when it wasn't it took 3 men and a boy to take in the main. I can't tell you how many times I wished for a simple slab reefing setup. Aside from failures and iffy sail shape, when reefing, you want to bring your center-of-effort in & down. When you furl your jib into a stormsail you move it up & out.
Its odd that you mention the Pardeys, as "Thelma" the boat that lin and larry rebuilt for racing in local regatas has a furled sail on both the foresail and the cutter........
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Old 11-03-2010, 15:20   #122
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As I stated, it is simply my belief that roller furlers are not good in heavy weather. One needs only to look around any marina to see that most people don't share my belief. I've seen them break out numerous times just sitting at the pier in a blow.
Other than the added expense of a furler the other reason I posted the original discussion was because since Christmas I have come into contact with one crew who had a furler seize then another that replaced a unit after it broke. Both were on mid/higher end cruising and racing yachts. I am not saying these failures are “common”, but obviously they do occur.
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Old 11-03-2010, 22:08   #123
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Oh yes. I had one coming apart after a bolt broke and here in Panama I see a lot of repairs being done on them after sailing through the heavy weather conditions off the Colombia coast. But I think much is caused by not using them right... grinding away on the furling line with an electric winch etc.
Even on Jedi, I can furl the jib by hand without the use of a winch (just a rope clutch).

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Old 11-03-2010, 22:20   #124
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A free flying a storm jib shouldn't be a problem structurally- the leech isn't transferring load to a stay, neither is the foot so why the problem with the luff?

This is probably a good time to bring in another point - probably a bit obvious, but probably worth stating.

Transfering lateral load to a stay is a really bad idea.

Think about pulling the string of a bow - the string is your forestay, the mast is the bow. This is the nature of the force that is present when you allow your hanks or luff tape to pull on the forestay - not pretty - Stays are designed to take load in tension along their length, they are incredibly bad at taking force laterally.

To combat this force we need to get halyard tension in stronger winds - remove as much lateral force as you can - the sail should be built to take this this load, if it can't, find a new sail maker. Don't forget the backstay / checkstay to counter the force.

The luff of the sail should not be significant part of the load transfer mechanism in stronger winds. Tack, Clew, Head - these are the strong bits - this is where the forces should go.

But, yes, don't try this with your new Light No.1
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Old 11-03-2010, 22:26   #125
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Last weekend we were on a passage race. We had just hoisted the spinnaker and I was driving and trimming. One person on brace, myself with one trimmer and the pit/mainsheet guy free. Immediately after the launch I had asked for the genny to be furled and there was lots going on at the mark.

I am watching the spin and see the genny going in (head out of the boat) and as I am trying to get the spin trimmed I am hearing in the backgroung talk of the winch handle. By the time I look down the fairly new crewman is grinding the furling line on the genny winch and about 30% of the genny is still out. I immediately look across the boat and sure enough the old working sheet for the genny is cleated off.

Winching the furling line, especially on my boat is never needed.
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Old 11-03-2010, 22:34   #126
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Yes, that's the way to break it. If you use a winch handle, you should feel that something is wrong; when you use electric winch, it's end of story.

It's the same with running backstays. The tails must never go on an electric winch. You can even pull the mast down that way.

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Old 11-03-2010, 22:42   #127
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Quote:
Originally Posted by bewitched View Post
A free flying a storm jib shouldn't be a problem structurally- the leech isn't transferring load to a stay, neither is the foot so why the problem with the luff?

This is probably a good time to bring in another point - probably a bit obvious, but probably worth stating.

Transfering lateral load to a stay is a really bad idea.

Think about pulling the string of a bow - the string is your forestay, the mast is the bow. This is the nature of the force that is present when you allow your hanks or luff tape to pull on the forestay - not pretty - Stays are designed to take load in tension along their length, they are incredibly bad at taking force laterally.

To combat this force we need to get halyard tension in stronger winds - remove as much lateral force as you can - the sail should be built to take this this load, if it can't, find a new sail maker. Don't forget the backstay / checkstay to counter the force.

The luff of the sail should not be significant part of the load transfer mechanism in stronger winds. Tack, Clew, Head - these are the strong bits - this is where the forces should go.

But, yes, don't try this with your new Light No.1
I am not sure I agree with this. Halyard tension is about sail shape not load transfer. If your theory were the case you wouldn't need a forestay the sail luff would be the forestay.

If you have adjustable backs they are for adjusting mast prebend and forestay tension.

With no jib cunningham halyard tension is used for sail shape. Whether foil mounted or hanked on, the load is transfered to the forestay along its entire length.

In fact the profurl unit I have has phenolic upper and lower attach points for the genny. My partner broke the lower attach fitting by grinding the genny halyard in an attempt to correct forestay sag in high winds. What was really needed (and I corrected during the furler repair) was the upper shrouds tensioned and the backstay tightened.
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Old 12-03-2010, 00:09   #128
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I am not sure I agree with this. Halyard tension is about sail shape not load transfer. If your theory were the case you wouldn't need a forestay the sail luff would be the forestay.
Correct - the storm jib / halyard takes the load - the forestay does nothing (or as close as you can get to nothing) - it has no structural function in this scenario
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Old 12-03-2010, 05:08   #129
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Correct - the storm jib / halyard takes the load - the forestay does nothing (or as close as you can get to nothing) - it has no structural function in this scenario
Ex-calif - you've got me thinking - perhaps this is a bit to simplistic and possibly not entirely accurate .

How about this?

Stays act in tension - take an inner forestay - It stops the mast attachment point moving away from the bow. When you hoist a sail on it, you introduce a force in exactly the opposite direction. The halyard tension tries to pull the mast towards the bow. The stay cannot react this force - it cannot act in compression (it is too slender). It goes slack (or at the very least has no tensile forces to speak of in it). The force is reacted by the checkstay.

However, there are lateral forces present (from the wind) and these will act on the sail, and so on the line of the halyard / sail / tack point that is now taking the loads that we have imposed by grinding on the halyard - trying to bend it to leeward. This line of tension is nigh on impossible to keep straight. We see this force as a sag in the stay.

At some point (and I can't define when this point is) if the lateral forces are of sufficient magnitute in relation to the tension in the halyard, a portion of that lateral load will attach to the stay and the sag of the forestay will cause the the stay to go into tension.

So yes, the stay does take some of the load.
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Old 12-03-2010, 12:05   #130
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I think that you would find that the stay takes the lateral loads in proportion to the tension on the stay vs. the tension on the sail's luff.

i.e. if the tension is equal between the sail luff and the stay. The lateral loads are equal.

If the stay tension is 3 times the sail tension. The stay caries 3 times what the sail full tape carry.

To put it another way, the amount of sag is proportional to the lateral forces divided by the tension.
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Old 12-03-2010, 14:48   #131
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You guys argue about engineering like it is politics.
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Old 12-03-2010, 20:42   #132
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Old 15-03-2010, 08:48   #133
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I am not disagreeing with theories here but...

The lateral loads on the foresail end up transfered at the top of the mast. But unless there are no hanks and no foil the loads are transferred along the length of the stay.

The lateral loads on the mainsail are transmited along the length of the mast due to the hanks with load centered parrallel to the center of pressure.

The lateral loads are transmitted from the mast via the shrouds to the chainplates, hull etc.

Maybe I am not getting this flying a storm jib stuff but If you add so much halyard tension thaqt all the loads are at the tack and head, why even have hanks at all? My guess is that it would fly like a spinnaker...
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Old 15-03-2010, 12:39   #134
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Not to hijack the thread but I frequently sail with an engineer freind of mine. I'm about as far from being an engineer as could be imagined (the math part of my brain short circuted when puberty hit)and our back and forth while trimming etc. is like some sailor's Lewis and Martin routine. The Zen of DIY
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Old 12-05-2010, 22:56   #135
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single or short handed furlers are better simple becouse it keeps people in the cokpit and of the for deck in the ruff.If it gets real bad 3reefs in the main looks pritty good or touch of furler beam on or down wind,any worse close up and find the rum
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