On 2007-10-08 21:41:39 -0400, Wayne.B said:

On Mon, 08 Oct 2007 18:22:30 -0700, Frogwatch
wrote:

I wish I'd gone with Norseman or Staylok instead of swaged terminals
when I rerigged. From what I see on the web, they last much longer
with no cracking of the swaged area.

I think that's a good plan if you have a way to load test them to SWL
off the boat. Otherwise you really need a *lot* of confidence in your
workmanship.

I believe that a Norsman or Staylok job is more likely done better by
amateurs than the usual "professional" job done by swagers.

Swaging depends upon deforming stainless stock in a controlled manner,
but there isn't a direct method of determining that the deformation was
properly performed. A poor swage won't show it's face for years. A
Norsman or Staylok job can be reviewed immediately.

--
Jere Lull
Tanzer 28 #4 out of Tolchester, MD
Xan's new pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI pages: http://homepage.mac.com/jerelull/BVI/

On Sun, 07 Oct 2007 16:44:16 -0700,
wrote:

I've managed to put two nicks in the 1/19 stainless forestay on my 32'
boat. Dont ask how, far too embarassing, suffice to say a hack saw got
drawn across the wire. Nothing was cut through, but two small chunks
got taken out of two strands. How dangerous is this?

Sand the edges smooth to reduce stress concentration. Wrap over the
nicks with very fine wire that is wet with epoxy, this will reenforce
the weak spot. If 17/19 of the original strength is not good enough,
there is far too little safety margin in the design.

Casady

On Tue, 09 Oct 2007 02:50:57 GMT, Brian Whatcott
wrote:

On Tue, 09 Oct 2007 01:58:09 GMT, (Richard
Casady) wrote:

... Most
failures of standing rigging I've seen happen at the fitting which is
less strong than the wire. Thus if you have a wire section at 90% of
strength, it's probably still not the weakest link.
...
What is the safety factor? That is the real question. If it is large
that would be one thing.

Casady


Now THERE'S an interesting question!
How would an engineer want to specify the rigging for a sailboat?
He might want to consider the peak loads applied to the rigging.
What could that be?
Perhaps it would be the gale that puts the main mast and sail parallel
to the water? The rigging forces could hardly get greater, possibly?

That would not be too difficult to measure, surely?
How about taking a main halliard offboard, abeam the mainmast, and
hooking it to a winch to pull the mast down, with a force meter
attached?

Not quite the distributed loading you'd get from the wind, but a
measure, all the same. Perhaps he would have the test repeated, with
the force applied 45 degrees forward of the beam, and then repeated
with the pull applied 45 degrees aft of the beam.


These are not diffficult tests to apply, surely?
Then an engineer would want to apply a design factor to account for
the variability in wire and fitting strenth as new, and during
service.
It might be a factor of 1.3, it might be a factor of 2.

Then he would compare his peak (factored) stresses against available
rigging wires, and pick the next convenient size larger. Bingo!

Or instead, he might choose a rigging size that is considerably
cheaper and slimmer, and declare the boat as "inshore" or "coastal".
Who knows?

Brian Whatcott Altus OK

Essentially the strength of rigging based on the effort to heel the
boat to its self-righting point times a safety factor.

Any boat design or professional rigging handbook should have the
calcs.

Or, ask Roger - this should be right down his alley.


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

On Oct 9, 3:05 am, wrote:
... Essentially the strength of rigging based on the effort to heel the
boat to its self-righting point times a safety factor.

Any boat design or professional rigging handbook should have the
calcs. ...

Yes, I think shrouds are typically sized to take about 3 times the
healing force at 30 degrees. Head stays are a little more
complicated. The NBS standard as described in the always useful
"Principles of Yacht Design", Larrson & Eliasson, does start from the
30 degree RM but the proper wire size uses a multiplier of 15.
However, I'm sure that IACC boats use much bigger multipliers and
little gaff rigged sloop could get away with a lot less. The loads on
the head stay are more properly functions of how stiff the boat is and
how effective the tensioning system is. You just can't have too much
headstay tension on a modern sloop. These days any reputable rig
designer (and there are specialists in this) will calculate the loads
from first principles. Since the static safety factor for the shrouds
is 2 to 3 times I'd expect a similar factor is built into the rules
for the headstay but I wouldn't bet a huge sum on that and it isn't
really easy to get there from transverse stability...

-- Tom.

nice BVI shots Jere...





On Oct 8, 6:47 pm, Jere Lull wrote:
On 2007-10-08 19:58:31 -0400, said:

On Oct 7, 7:44 pm, wrote:
I've managed to put two nicks in the 1/19 stainless forestay on my 32'
boat. Dont ask how, far too embarassing, suffice to say a hack saw got
drawn across the wire. Nothing was cut through, but two small chunks
got taken out of two strands. How dangerous is this?

here's the orginal poster back. The stay is four years old, the nicks
are nicks, not gouges. Perhaps 1/8 of the strand's total diameter?
Point about I already know the answer is well taken. I shall have to
pay for my stupidity, as it aint worth the dismasting. (Just consider
the deductible!)

Thank you!

I love it when a questioner comes back and says what he/she decided,
based upon our collective opinions.

Expect you won't be using the forestay as a sawing surface again.... ;-)

[Don't worry, all of us who have been around for a while have done
stupider things. Some of us are strong enough to admit to them. (I'm
not sure I'm one of that crowd.)]

--
Jere Lull
Tanzer 28 #4 out of Tolchester, MD
Xan's new pages:http://web.mac.com/jerelull/iWeb/Xan/
Our BVI pages:http://homepage.mac.com/jerelull/BVI/

"~^ beancounter ~^" wrote in message
oups.com...
nice BVD shorts Jere...

Must you gay up every post?

Wilbur Hubbard