Stays .. Losing Your Mast ... - Page 3 - SailNet Community
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post #21 of 51 Old 12-31-2006
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I just lost my whole post on this and I'm not gonna retype it! In short, this is a matter of naval archetecture and simply doubling up does not address the many other parts of the mast system that are in play. We cannot look at it piecemeal.
As far as the statistical analysis goes; if we already have an extremely low incidence of failure how much is it worth to half that failure rate. We must consider the marginal utility of the money invested and where it could otherwise be spent for potential greater increases in safety. Inverting that argument is why I do not play the lottery!
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Quote:
Originally Posted by HenkMeuzelaar
Wind Magic, by all means DO go with your own intuition (viz. to use redundant back-up stays or shrouds) rather than to just make everything stronger, as advised by some posters! The relevant failure statistics are pretty straightforward. In short, if you are dealing with a low probability failure event (such as rigging failure) redundancy wins hands down, whereas for high probability failure events upgrading/reinforcing may make more sense.

Here is why: Imagine you have a standard shroud or stay with a .01 (1 in 100) failure probability under a particular shortlasting set of circumstances. By installing gold-plated wire/rod/fittings etc. you would be very lucky indeed to bring that failure probability down by 10-fold (i.e. to .001), simply because even the most carefully manufactured metal component has a finite threshold probability of possessing hidden flaws.... Incidentally, similar threshold phenomena will plague the efficacy of your installation and/or maintenance procedures as well. In other words, it will never become perfect.

On the other hand, by backing that stay or shroud up with an independently attached stay or shroud of equal strength the probability of near-simultaneous failure will basically be reduced by a factor 100 (i.e. to .0001).
This post is thinking what I was feeling, I'm so glad that HenkMeuzelaar was able to put it into words. Relying on one cable as a backstay, for example, is relying on so much. For it all to work the chainplate has to hold, the metal in the cable has to be good, pins, turnbuckle, various nuts and bolts, etc, it all has to work. That is, none of it can have manufacturing defects, be made out of cheap metal, none of it can be suffering from fatigue, be overly stressed, etc, it all has to be right. And in terms of maintenance you HAVE to see the problems when they occur, you have to see strands coming apart, bent pieces of metal, worn pins, etc, and in order for the stay or shroud to be right you even have to see things that cannot be seen! Just because you can't see it during an inspection doesn't mean it can't fail, it's not fair, but life isn't fair, stuff just happens. And beyond all of that a single backstay for example is still a single backstay, a collision can hit it "just right" and break it, or I don't know, all kinds of things, it's a single point of failure. So basically you are putting the security of your mast in the hands of not just one single point of failure, but at least two including the forestay. Maybe if your upper shroud breaks your lower one will still keep the mast up. But depending on a single forestay and a single backstay is rolling the dice and having hopes for the best.

But like Henk said, having a backup with the same characteristics greatly reduces the odds. And it does happen, how many of us know someone who has lost a mast ? How many of us have lost one ourselves ? How many bad storm stories have "dismasted" in them ? I haven't lost a mast, but I feel it is lack of time on a boat that is the reason why, not any particular gift I have for sailing. Odds are very low that a stay will break, I agree with that, and that's great for a sailor who is outside the mouth of the Bay and just starts the motor up and goes back to port to get everything sorted out. But it is a whole different story for someone out in the middle of the Atlantic ocean in a storm, right ? We cruisers will take the performance hit to get somewhere safely and reliably, for a cruiser it's not about how long it takes to get there, it's about getting there safely, so we don't need fin keels and absolutely the perfect sail shape, we just want safety and reliability at a cost we can afford.

I think Mark Matthews expresses the thoughts of everyone with regards to the odds and standing rigging in the opening paragraph of his article here on Sailnet about standing rigging maintenance. He says ...

Quote:
Originally Posted by Mark Matthews
If you've ever had the unfortunate experience of watching a rig topple over the side, chances are you are more diligent now when it comes to maintaining the many fittings that keep the mast standing than you once were. And if your sailing experience doesn't include that kind of calamity, you've either been doing something right all along, or the sailing gods have simply opted to keep you in their favor. Regardless, you still might want to avail yourself of some essential tips for keeping your rig in the upright position, without relying too much on the whimsy of fate.
Reading that article you get the understanding of just how critical every little piece of hardware is to that chain of chances that is your backstay. Any little thing could cause it to fail, and there is a reason everyone is so concerned about inspecting it and so diligent about it's maintenance. It's because it's important, and because it's necessary given that each wire is a single point of failure. Because if you don't do it "just right", you could lose your mast. Which would be very bad! It's so critical that I've even read about people X-raying these parts to make sure they are right. Yet, even with good maintenance there is still a chance it could fail, remote, but experience of sailors in general says it can happen. Does it have to ? Or is there something we can do about it ?

I'm mystified by the argument that it's not good practice to have a backup for your standing rigging. Sailors are absolutely nuts about backups and spares, spare GPS, backup for the hull (the lifeboat), redundant means of self-steering, extra parts for same, backup radios, spare tiller handle, ditch bag, backup backup backup. And yet not to backup the very thing that keeps the mast standing upright ? Why ? I mean people even talk about storing a spare handheld GPS receiver in their microwave so that the microwave will act as a Faraday cage to protect the GPS from a lightning strike, many sailors even carry celestial navigation gear in case the whole GPS satellite system suddenly stops working! ... yet we trust that single metal wire that is solely responsible for holding the mast up ?

I wonder if this just isn't another one of those racing things. That maybe all of this came about because many boats were designed to race, and not by design to cruise. I mean was it cruisers who pushed these design decisions, were cruisers lining up at the front door demanding that rigging be made lighter, thinner, with less windage, and no backups or spares ? Why would we care about that ? The only time most of us even mention the word windage is when we are talking about reducing it when at anchor during a hurricane so that we don't drag anchor ...

Last edited by wind_magic; 12-31-2006 at 11:03 AM.
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post #23 of 51 Old 12-31-2006
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Windmagic, Henk is giving you his perspective as an offshore passagemaker. He wants redundancy, because he doesn't want to lose his mast 1000 miles from nowhere. When a boat goes offshore, it's sails, rig and hull take more of a beating, and age faster than when it's used for more local purposes. An overwhelming majority of sailors work 5 days a week, and sail on weekends on lakes, bays and along the coasts. That type of sailing is much easier on the rig, and the liklihood of failure is much less. Walk the docks and you'll see that very few boats are rigged for redundant mast support systems. You're getting good advice from both perspectives. It all depends on how you plan to use your boat. If you're going to sail a lightly built coastal cruiser on weekends until you retire, then you don't need redundancy. If you're preparing a boat for serious offshore passagemaking, then you probably will.
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post #24 of 51 Old 12-31-2006
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This is an interesting post. We all want to be safe, and therefore don't want to lose the mast. That could be 1000 miles from shore or 100 yards outside the marina. However, if the boat is designed correctly, and you sail it as designed, your chances of keeping the mast up are pretty good. Maintenance to keep it safe, and a plan for what to do when the **** hits the fan, are part of good seamanship. Know what halyard to connect where will keep it up until you can repair it. Having a spare stay, or the components, is practical on a cruising vessel. Redundancy in supplies is a good thing if you are far from West Marine.

One thing not mentioned, and I am somewhat surprised, is the safety downside of adding those additional stays. A clear deck is a good deck when you have to go forward to fasten that halyard to keep the rig from coming down. The more stays you add, the more impeded you are going to be. I kind of picture all these stays becoming a fence. Might be good for fending off pirates if you connect it to your battery bank. I certainly don't see it improving the rig.

Do your maintenace, watch the weather windows, and GO SAILING!
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post #25 of 51 Old 12-31-2006
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It used to be that folks who were going where the rig would be exposed to heavy weather when far from home would simply up-size their standing rig and reinforce chainplates and attachments.
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post #26 of 51 Old 01-01-2007
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Though I have no special expertise in the area FWIW here are several observations.

1) I think Sailaway is right in that the kind of rertofit you are talking about is probably very expensive. Think in terms of thousands of dollars. It would definately help to think in terms of a specific boat, as some boats maybe more amenable to this kind of upgrade that others. Regardless I think you are looking at significant naval architechure and engineering issues.

2) Some of the hardware you need might have to be custom made. The design, prototyping, and manufacture of a single piece of hardware is very expensive. This is if you even find someone with the requisite experience to do it. I am thinking here specifically of the masthead and its fittings. Don't forget about access to and possible to reinforce the stem and sternpost. If access is bad to those areas there may have to be significant demolition and rebuilding of the bow and stern.

3) You might want to post your question here ssca forums . I know that Evans Starzinger posts there regularly. Several years ago he and Beth Leonard had boat custom built for extensive high lattitude sailing. He and others might have some additional insights for you.

4) Ask Bob Perry, at http://www.perryboat.com/page/consult as one of the preminent designers around I am sure he has some thoughts on the subject. BTW, as far as I know, none of the Valiant line has double forestays or backstays.

5) You might find the addition of a removable interforestay and running backstays a far more doable upgrade than true double forestays and backstays. Removable interforestays and running backstays are not the same thing as true double forestays and backstays.

6) The vast number of boats cruising do not have the type of arrangement you are considering and successfully complete their cruises and circumnavigations.

7) All of the statistical analysis that HenkMeuzelaar refers to is only valid if materials and construction that go in to a project like this are at least as good if not better that the original materials and construction.
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post #27 of 51 Old 01-01-2007
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To me...this whole thread is somewhat neurotic. Various EXISTING rigs have been proposed which minimize any danger of dis-masting. Actual dismastings that are not maintenance or race related are rare AND the most telling point is that NO ONE here or anyone they know has done or feels any need to do what Wind_Magic is proposing. There is such a thing as worrying too much!!
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post #28 of 51 Old 01-01-2007
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WM, if you are really that concerned, buy an SC 31. They have 1 outer, 1 inner forestay, split backstay, and 4 shrouds on each side (2 act as modified running backstays). The mast is the size of one on a 45 foot boat! The only downside is that it is deck stepped. However, this can be an advantage when trying to get rid of a downed mast in a storm (but you will have nothing to rig a temp sail on). The compression post is solid mahogony and is almost the size of the mast and it runs right into the full keel. The chainplates run almost 1-1/2 feet down some serious bulkead reinforcements (all 4 on each side!). Thomas Gilmer built the first fiberglass boat to circumnavigate the globe!
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post #29 of 51 Old 01-01-2007
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Quote:
Originally Posted by southerncross31
Thomas Gilmer built the first fiberglass boat to circumnavigate the globe!
The first fiberglass boat to sail around the word was a Seawind Ketch designed by a professor of navel architecture and author of textbooks on the subject named Thomas Gillmer but not built by him. The boat was built by the Allied Boat Company in the Catskills New York.
All the best,
Robert Gainer
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post #30 of 51 Old 01-01-2007
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Quote:
Originally Posted by camaraderie
To me...this whole thread is somewhat neurotic. Various EXISTING rigs have been proposed which minimize any danger of dis-masting. Actual dismastings that are not maintenance or race related are rare AND the most telling point is that NO ONE here or anyone they know has done or feels any need to do what Wind_Magic is proposing. There is such a thing as worrying too much!!
I agree with you as I never have before!!!

Maybe better and safer to stay at home, in the sofa.

The way this is going, the next thing I recommend you check are the thru hulls, the seam between deck and hull, and the keel attachment.

Humm better stay home... Much safer, still I know an old guy that died at home in the sofa!!

Do you know what kills more people here??? the BED!!!! Statistically more people die in bed than from dismasting.

DO NOT GO TO BED!!!
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