Standing Rigging Specs

[Coastal Nomad]

Hi All,
Am looking for a resource for standing rigging specifications (tension, wire size/length, etc.) for a '81 H27 with a Mk. 2 Kenyon mast, hank on forestay and split backstay. Am working towards replacing my standing rigging and just purchased my rig tension tool. Not a pro rigger but can see some trouble coming in the boat's future. Any help would be appreciated.

Thanks,
Mike
S/V Coastal Nomad
(Highly skilled cruising marine electrician who works for beer, smokes and slip fees...and other important boat stuff ;-)

 

[jviss]

Do you have the old rigging? Plus, Hunter is still in business, so their customer service folk may help.

Here's where you can ask them a technical question:
https://www.marlow-hunter.com/contact/technical-question/

 

[Coastal Nomad]

Do you have the old rigging?

Standing rigging is still on the boat and is functional. Am a full time cruiser and can feel that something isn't right with my side stays and shrouds. Had a rigger do a non-insurance survey a couple of years ago and everything was found to be in good condition. However, I have spoken to the 3 previous owners dating back to 2001 and none of them had done anything to the rigging except the last owner who had a friend help him tune the standing rigging. Feeling that it's time to do something. Am purchasing Sta-Loks a bit at a time here to replace the existing swadged connections. New wire is already onboard. Will try the link you sent. Thanks for that bit! ;-)

 

[joe28532]

According to Hunter the tension spec is 20%. See here: https://www.marlow-hunter.com/wp-content/export/Miscellaneous/Standing rigging tension.pdf That doesn't mean that every wire should be set to 20% of the breaking strength though. The cap shrouds and backstay should be after they are tuned correctly but the lowers are for shaping and keeping the mast in column under sail so their tension is determined by the tuning under sail process. The forward lowers will be looser than the cap shrouds and the aft lowers will be looser than the forwards.

 

[dLj]

A note on sta-loks. They are excellent fasteners, arguably better than swaged fittings. But when assembling them, it is recommended to proof test after assembly. Two things happen with this, one is that sometimes they don't get seated correctly and that will identify that and two is that there is typically a small elongation where everything seats. Nice to have this done prior to tuning your rigging rather than during a hard blow and having the rigging change as your sailing... Just food for thought...

dj

 

[jviss]

Interesting. I have installed Sta-Loks - only seven, in total, on the shrouds and backstay of a C3. I never saw anything in the product docs about "proof testing" them, and never had an issue with rig tuning.

 

[dLj]

I'm not surprised. They work very well. And most of the time seat well. You will only find this type of information if you are working with overhead applications in industrial settings. Standing rigging on a boat is not, for some reason, considered an overhead application, hence the acceptable use of swaged fittings. Swagged fittings are not considered overhead capable in any industry that I am aware of.

The requirement for proof testing comes out of places like elevators and other similar type applications. It would not come from the manufacturer of the Sta-lok fitting.

It is perhaps a bit of over-kill to proof test, but that does seem to be my particular MO...

dj

p.s. In my original post, I probably should have said in some industries, proof testing is required.

 

[jviss]

I guess I keyed off the term "proof testing," which often means a load that is in excess to what is expected to be encountered in normal use, as in firearms proof testing.

 

[dLj]

You are correct, that is what "proof testing" is. I have no idea of what kind of loads all the various standing rigging bits might be expected to have to withstand. That would be an interesting to know.

The standing rigging would have the maximum expected load, then the rigging should have a design safety factor typically somewhere in the 150% to 250% of that maximum load. 150% for a sailboat would seem to me to be a racing only type factor as that doesn't give you a lot of leeway, but whatever. Proof testing the fittings would then go to something like 110% to 150% of the expected maximum load depending upon what kind of design safety was implemented and the engineer of records particular preference. I've also seen proof testing done at 75% of maximum expected load, especially on these types of fittings as they are pretty robust and if you get to 75% of maximum load and nothing moves, they likely aren't going to move...

I don't know if a standard exists on the safety factors. If there is one, I've never seen it. As far as I'm aware, these are all industry specific and fall under "best practices". Often a particular design engineer has these in their tool box of "best practices" that comes from years of experience in a specific field.

From my somewhat limited knowledge of sailing and standing rigging, I think these "safety factors" are likely all in specific designers heads. I used to have the German standard (can't think of the name of it right now off the top of my head) on standing rigging for commercial boats. That was one complicated bear to read through. I'll have to dig through my old papers and see if I can still dig it up. But right now I'm sailing and nowhere near home...

dj

 

[Coastal Nomad]

Thanks all for the informative replies! Hadn't considered proof-testing but I like the idea and will investigate it. Currently my fore and back stays are at 20-22% which I will leave as is. Fore and aft shrouds are at 17%. The side stays are at 15% and 16% (port and stbd respectively) and that is where I'm feeling my issue is. I'll adjust the side stays and shrouds up to 18% dockside, go aloft and check wire and swage connections as best I can and then adjust accordingly while underway...if I can get ever some wind that is. Again, thanks for the good info!

 

[Coastal Nomad]

I used to have the German standard (can't think of the name of it right now off the top of my head) on standing rigging for commercial boats. That was one complicated bear to read through.
dj

Germanischer Lloyds (GL). And yes, anything from GL is a complicated bear to read through. Have had to deal with them in a past life building yachts (retired marine electrician and general mechanic here).

 

[dLj]

Germanischer Lloyds (GL). And yes, anything from GL is a complicated bear to read through. Have had to deal with them in a past life building yachts (retired marine electrician and general mechanic here).

That's the one! My copy had a cover in black with gold lettering used to print the title and such. I had to get the English edition as my German is non-existent and had to wait quite some time for it to get sent to me (not to mention it wasn't cheap). It was pretty snazzy looking... Cost me hours of reading time to wrap my head around it. I had to design the rigging for a wooden sailboat that was a ketch. It was a lot of fun (I know, I have a sick sense of fun) to figure it all out. That was along time ago.... Thanks for the reference!

dj

 

[Coastal Nomad]

It was a lot of fun (I know, I have a sick sense of fun) to figure it all out. That was along time ago.... Thanks for the reference!

dj

Yep, porn for engineers! Lotsa fun to be had. I have the entire set of GL books for yachts up to 300 tons in .PDF format (employer paid for it and yeah, not cheap). ;-)

 

[joe28532]

I highly recommend Ivar Dedekam's book "Sail and rig tuning". A simple read and will leave you with a great DIY understanding.

 

[h2o_snow]

Joe,

Thanks for the recommend - just ordered.