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Subject: Re: [worldcruising] Rigging & Tension
From: Barry Brazier (ozboats@XXX.XXX)
Date: Thu Jul 11 2002 - 22:52:38 EDT
I don't believe it is possible to see signs of immanent failure in SS rigging. The main cause of failure is fatigue caused by constant vibration of the rig. This occurs even while at the moorings. I have seen apparently sound SS wire break when 10 YO. I have lost a mast for the same reason. I always now replace before 10 years. Think 7years is the safe limit for wire and longer for fittings. Fittings don't deform as much and therefore have less fatigue.
This applies to all SS fittings that have varying loads. I recently had my rudder blade break loose from the rudder shaft due to fatigue at the junctions were the SS fingers in the blade are welded to the shaft inside the fibre glass covering.
SS is fatigues faster than non stainless steel I would expect 20 years from galve fittings. The problems with them is corrosion.
I have found a good way to tension the rig of a cruising boat is to sail on a fine reach in 15 kt wind so that the rigging on the leeward side is slack. I then tighten that lee rigging to take up the slack.
Then go about and do the same on the other side. This works for a single spreader rig.
Regards
Barry
----- Original Message -----
From: Ray Thackeray
To: worldcruising@XXX.XXX
Sent: Tuesday, July 16, 2002 3:19 PM
Subject: RE: [worldcruising] Rigging Tension
Perhaps I was a little inflammatory by saying "25%" of breaking strain
for rigging tension was "not useful information". But after over 21,000
nautical miles of sailing, I think I at least have a little experience
(not as much as some...).
However, the bottom line is that for most people it is impossible to
find out a) what the breaking strain is for their rig - is it for
terminals, for wire, or what? and b) how the hell do you measure it?
My boat is a 51' Offshore Garden Ketch - and after 10 years of
ownership, I have never found anything in any manual, documentation or
other general reading to tell me what the breaking strain of my own rig
is. On top of that, I know of no product I can buy that would give me
that measurement.
Finally, my rig hasn't fallen overboard after over 20 years of sailing
and no replacement!
The usual advice, of course, is to replace all the wire and terminals
every 10 years. Frankly, I think that's too general - I would rather
inspect the rig and look for cracks (at least, in stainless steel) or
deformities (in galvanised steel). But in a well rigged vessel sailed
conservatively, I have found that wire and terminals can last well above
the usual advice given by boat yards - who want to charge you $10K for a
re-rig.
Ray
-----Original Message-----
From: Karl [mailto:kbert@XXX.XXX]
Sent: Monday, July 15, 2002 7:26 PM
To: worldcruising@XXX.XXX
Subject: Re: [worldcruising] Rigging Tension
Yeah, well...
Book learnin' is one thing, but I sure wouldn't want
to be sailing any vessel with rigging tensioned anywhere
near 25% of breaking strength!
Sometimes some folks know more than _most people_
simply from experience.
Lighten up, Karl
----- Original Message -----
From: <truelove39@XXX.XXX>
To: <worldcruising@XXX.XXX>
Sent: Sunday, July 14, 2002 9:20 AM
Subject: Re: [worldcruising] Rigging Tension
> The man asked for rules of thumb; the one I quoted is in many rigging
books.
>
> He didn't ask for a dissertation; but I see that you're one of those
experts
> who knows more than most people.
>
> John
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