Testing standing rigging

[TreblePlink]

My rigging is very old, but has never had saltwater exposure (yet) and looks pristine. It's all 1/4" 1x19 on a 28' sloop.

Rather than replace it, a Communications Tower Rigger friend suggested I test it - he has the means to apply and measure tension up to 10,000 pounds.

Seems like if it survives 30 percent of it's rated breaking strength without pulling out of the crimps, odds are strong it's fine ...

A cynic might suggest this is rarely done by sailboat service providers due to profit reduction. But there might be more to it ...

Anybody done this?

[paulajayne]

NDT (Non Destructive Testing) is fine in many cases but with rigging I would not suggest you do it, as applying 30% of its rated capacity could and I believe would weaken it.

[Flyingriki]

From my rigger:
Unfortunately the only way to truly assess the inside of a metallic fitting is to destroy it... I completely agree. When shopping for a boat, if the rigging is even close to 15 years old I'd replace the standing rigging without hesitation. I've seen too many failures past that point.

And if it's a multihull my cutoff is 10 years.

[Captsteve53]

Modern X-ray/Ultrasonic's equipment (just for the record ) can check all these fittings for there condition, (now saying that the financials may be be the issue, although most of the equipment today is totally portable and small)

Modern stainless steel shrouds themselves rarely break, but the fittings to the mast or the boat dos fail, with consequent failure of the mast.

Commonly shrouds for example are pre tension ed to 15% of the breaking load,This figure works for all diameters of wires

Bottom line SS rigging is suggested / recommended to be changed out at 10 years (that is in Salt water how ever)

Cheers Steve(MIIMS-Lloyd's Maritime)

[Captsteve53]

Sorry , forgot to say the typical breaking load on your 1/4" 1 x 19 is 7584 Lb's (34 Kn)

So your normal pre set tension @ 15% is 1138 Lb's

Cheers Steve

[TreblePlink]

Originally Posted by Captsteve53

... Modern stainless steel shrouds themselves rarely break, but the fittings to the mast or the boat dos fail, with consequent failure of the mast...

Cheers Steve(MIIMS-Lloyd's Maritime)

So, chainplates, pins, and turnbuckles are the usual suspects?

[Captsteve53]

Yes, but the worst failure rate is with the swage it's self, there are quite often micro cracks (Ultrasonic,s/thermal imaging Would find) in the fitting after the pressing stage, some use rollers and other just a press die, Stainless work hardens really well so after the compression process these fittings are stressed to begin with,

If on a budget then a simple dye penetrant check will do a reasonable job, they come in a three pack the cleaner/the Penetrate/the developer, they actually have good results if you follow the directions to the letter. I normally check all fittings on the rig (with special attention to the swages ,

Below is a picture of a bow fitting holding the fore stay (a bit scary!!) after checking with dye penetrant

Cheers Steve

[TreblePlink]

Thanks!

Now to find dye penetrant ...

[Flyingriki]

Don't forget that insurance companies will look at rigging age in a claim involving a rig failure. If it's too old they'll say it wasn't maintained and you're out of luck. My last broker tried her best to get me to ignore that, until the rigger at the haul out gave her a lecture.....

[Captsteve53]

Same fore stay fitting but the opposite side, this fitting had been modified and repair welded some years back,

Cheers Steve

[Captsteve53]

Check with welding supply shops or here:Dye Penetrant Inspection Materials - NDTSupply.com

Cheers Steve

[TreblePlink]

One last question;

On a sloop, what standing rigging fails most frequently?

(Intuitively I would guess top shrouds, but I don't know)

[Captsteve53]

Yes, Probably the most failures i see are cap shrouds followed by the inner's and then fore stay (caused by halyard wraps etc)

Below is a basic check list put out by Boat US


Cheers Steve

[Snowpetrel]

Ive seen plenty of strands fail just inside the swage fitting. Pretty hard to spot Stress corrosion cracking on a buried strand.

Another place that seems to regularly give problems is the lower tangs and tang bolt. These get pretty heavily loaded when deep reefed.

[Fore and Aft]

I am with you Ben. A lot of rigging failures are really hard to see or predict where they are going to happen.
After surveying a yacht where the mast fell down diagonally to the starboard aft side I am a little nervous around old rigging. No one was hurt in the incident but the Yacht had plenty of damage.
Cheers