Disaster Averted

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David Mellon
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Disaster Averted

Post by David Mellon » Sun May 17, 2009 3:43 pm

After a wonderful weekend at White's Landing, Catalina Island we left our mooring at about 7:30am. We had a flat water crossing at 19mph, passing through a pod of porpoise and light traffic in the channel. As I crossed a large wake inside the Long Beach Harbor breakwater my stock forestay with roller furler mounted broke free from the hounds and fell to starboard, staying on board caught in the standing rigging. As I watched the mast falling towards my forehead I breathed a sigh of relief. My mast raising system was in place and the mast fell just a few inches and stopped. I have a habit of leaving the mast raiser in place, with the winch backed off half a turn, unless I am going to sail. I find it is easier to move about the foredeck with the gin pole there to grab hold of. My advice is to do the same, our rigging can take a pounding under power and my three year old forestay had reached its limit. Next I will be researching forestays, what is the thickest cable I can use with my CDI furler and how long must it be? Also I will need to learn to dismantle the system and rebuild it.

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Night Sailor
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Re: Disaster Averted

Post by Night Sailor » Sun May 17, 2009 4:28 pm

Yours may be a good example of how pounding at high speed, even in releative flat water can put very hard strain on hardware, especially mast components, since the mast is like a giant lever compounding the forces as it trys to pivot from the cabin top tabernacle fulcrum.
Measure the size of the hole in the furler foil, and allow slight room for the foil to rotate about the forestay wire. That is the maximum size.

I believe it is helpful too, to have the rig tighter than most Macs are rigged. My thinking is, it reduces the momentum of components so reduces friction and wear, especially in choppy waters, or long sea miles under power at speed.

Some on this forum also habitually rig the jib or spinnaker halyard to the pulpit as a kind of backup forestay.

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Re: Disaster Averted

Post by waternwaves » Sun May 17, 2009 9:16 pm

leaving the mast raising system attached and under tension contributed to the failure

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pokerrick1
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Re: Disaster Averted

Post by pokerrick1 » Sun May 17, 2009 9:36 pm

waternwaves wrote:leaving the mast raising system attached and under tension contributed to the failure
I understand your thinking - - - but with the winch "backed off" didn't that negate the effects which you are considering?? Enlighten me please!

I have never left the mast raiser in place - - - but I have considered it?

Rick :) :macm:

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RussMT
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Re: Disaster Averted

Post by RussMT » Sun May 17, 2009 9:53 pm

I'm confused. What actually failed? Was it the fore stay?

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David Mellon
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Re: Disaster Averted

Post by David Mellon » Mon May 18, 2009 1:19 am

The mast raiser was backed off and absolutely could not have contributed to failure. The forestay snapped just inside the top of the roller furler. Upon inspection it was kinked where it entered the furler, by the furler. After I install the largest cable that will fit I will be inspecting it on a regular basis. It took three years for this damage to become critical and I suggest everyone inspect the stay where it enters the furler, especially if you raise and lower the mast a lot as I do. The way I figure it, when moving the mast back and forth for trailering, the furler was jammed towards the top of the mast repeatedly causing a kink in the very top of the stay as it enters the furler. I may consider doing as others have and remove the furler from the mast entirely and laying the unit on the deck for trailering.

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delevi
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Re: Disaster Averted

Post by delevi » Mon May 18, 2009 2:19 am

David,
My previous forestay was on the verge of failure in the exact same place as yours. Approximately half the wires were broken off. Fortunately, I noticed it in time and replaced it. Wires break with chafe. That's just the way it is. Had the same issue with lifelines splitting wires where they enter the stantions. Also, when derigged, the furler will cause a kink. I never noticed it before. What I do now after lowering and setting the mast is put a small bungee right at the top of the furler and tension to the mast to keep the furler from pulling away. This keeps furler and cable in line so it won't kink. The CDI furler will take up to a 3/16" cable. I went with 5/32" which is still much stronger than the stock 1/8" I considered 3/16 but was concerned about load distribution. Since the shrouds are 5/32, and it takes more tension to keep a thicker wire tight than a thinner one, and considering the rig was designed with a 1/8" forestay to begin with, I figure achieving rig balance may be a problem with a 3/16 forestay. I'm not certain about this but this was my line of thinking. Also, going with the thickest cable the furler will accept may contribute to additional chafe.

As for keeping the mast raising gear in place... not for me, though can't argue with the fact that it saved your but.

Leon

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David Mellon
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Re: Disaster Averted

Post by David Mellon » Mon May 18, 2009 2:36 am

Leon, thanks for your detailed response! I understand your logic and will go with 5/32" as well. If I decide not to remove the furler I will follow your advice and keep the system aligned with a bungee. As for safety, maybe I'll run a light line from the mastead to the pulpit, it could be thin and under no tension and still save my butt, it doesn't take much to keep the mast upright.

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Re: Disaster Averted

Post by waternwaves » Mon May 18, 2009 3:02 am

any additional tension on the front of the mast decreases forestay tension. and increases backstay tension eg..spinnaker, 2nd forestay etc...many with the roller furler attach the jib halyard to the pulpit for similar reason. There are limits to how stiff a 26 can be.

the facts are.

anything decreasing forestay tension allows the pins to loosen and the cables to whip more. This slack allows greater travel of components when they are loaded in the reverse direction. including the unloaded furler. this slack can appear with chafed strands, knots, twisted pins, pins that fall out, and failed compression fittings and connections.

Like most things on the boat their are tradeoffs.

a safety line for the forestay should be loose and should catch after failure. not be tensioned and inplace. Forces on a sailboat are balanced, an increase in force in one location results in higher loads elsewhere.

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David Mellon
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Re: Disaster Averted

Post by David Mellon » Mon May 18, 2009 3:40 am

Exactly, that's why my mast raiser was slack and I would not keep a safety line under tension, just very glad it was in place!

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Re: Disaster Averted

Post by bastonjock » Mon May 18, 2009 6:31 am

Glad to hear that the whole lot did not come crashing down,i generally use my jib halyard as a safety line,but i find that i catches the sails,so ive been thinking of running a slack dedicated safety line using the mast rasing fixture on the deck.

I also noticed that when i tightened the rigging,that items such as the backstay needed readjusting,im considering and adjustable backstay,fixing it to both rear quarters

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irayone
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Re: Disaster Averted

Post by irayone » Mon May 18, 2009 11:17 am

I am confused....I thought the mast rasing system was to be left attached to the mast while sailing??? As shown in the Mac instruction booklet.

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delevi
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Re: Disaster Averted

Post by delevi » Mon May 18, 2009 12:23 pm

I am confused....I thought the mast rasing system was to be left attached to the mast while sailing??? As shown in the Mac instruction booklet.
No. The manual doesn't say that. Your jib will hang up when tacking, among numerous other reasons not to have it up there. Don't sail with it.

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Re: Disaster Averted

Post by irayone » Mon May 18, 2009 4:36 pm

I removed the line that attached to the forward cleat. The mast raising system stays up holding on to the mast and the two lower shrouds. The instruction sheet says do not remove them from the line which attaches to the mast??????

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Re: Disaster Averted

Post by irayone » Mon May 18, 2009 5:03 pm

Page 10 of the instruction manual states " The "U" shaped bracket is bolted to the mast...There is a 3 inch long loop tied to the winch line with a bowline knot. Do not untie this loop. The side support wires are captured in this loop.......
Do I disconnet the bowline at the mast via the shackle and connect the two shroud lines and the winch bowline to the shackle????

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