A few toggle design choices

[Douglas]

Ahoy Mat ,,,, F W I W ,,,, I don't like ss strap toggles . My used boat came with SS strap toggles on the SS chain plates . The SS strap toggles were clean and bright, no rust showing .

Upon disassembly I found spider web like cracks emanating from the C/P pin holes ,,,, these weren't visable , assembled , because the strap covered the area .

Later I come to find out that stagnant salt water causes crevice corrosion on SS .

My strap toggles were holding salt water drops between the C/P's and toggle straps , thus the crevice corrosion , so, bad SS design in my book .

[Brion Toss]

Hello,
As a Coastie once told me, "I reserve the right to be smarter than I used to be, and dumber than I am going to be." So I no longer recommend toggles at both ends of turnbuckles, just the bottoms, for nearly all rigs.
T-bars are the most failure-prone terminal, something even Navtec agrees with. You might consider abandoning those T-tangs and installing real ones, especially if you are considering serious voyaging. That way you can go all-Hayn, too.

[Brion Toss]

Hello,
As a Coastie once told me, "I reserve the right to be smarter than I used to be, and dumber than I am going to be." So I no longer recommend toggles at both ends of turnbuckles, just the bottoms, for nearly all rigs. Get a turnbuckle body with left-handed strap toggle stud, and thread a Hayn right-handed stud into the top.
T-bars are the most failure-prone terminal, something even Navtec agrees with. You might consider abandoning those T-tangs and installing real ones, especially if you are considering serious voyaging. That way you can go all-Hayn, too.
For the masthead, you can get a built-in toggle, like the one you linked to, from Hayn, or use a separate fitting. The type of toggle you use (forged, double-jaw, or eye-jaw strap toggle) is not as important as the brand. Go with Hayn or Navtec or Schaefer. Specifics like masthead mortise width and terminal type might drive the conformation.
As for strap toggles and crevice corrosion, correlation is not causation; the toggles are not a particular source of the problem. Water is.
Fair leads,
Brion Toss

[Douglas]

Ahoy All ,,,, I am curious as to how the "Tee" on the tee-bolt stud toggle is formed ,,,, does anyone have a clue ?

Also has anyone put their 50 power h/h Edmund Scientific microscope on the bent over area of a SS plate toggle ? Would they notice deformation cracking at that bend and if not , "How Do They Do That" process without cracks showing up ?

My information on SS crevice corrosion comes from the paper mill industry in the PNW . Seems that the pulp bleaching SS tanks were developing pin hole leaks near the SS tank joint welds .
The research discovered the problem as a free chloride ion attacking that weld area , and causing pin hole corrosion .

Later I find out my SS water tanks onboard were suffering the same pin hole corrosion ,,, the cause determined to be bleech or chlorine in the water to sterilize that tank water , taken onboard from city water systems delivered fresh water . Ah , Ha ! so that is what ruined my onboard SS water tanks !


Now , later , thinking 2 + 2 ,,,, salt in salt water is a sodium chloride solution, with plenty of free chloride ions .

What I learned even later ,,,, was ,,,, that when you weld SS ,, the molten welding puddle boils off a portion of the nickel content ,,,, so you don't have SS 18-8 at the weld area anymore , but an alloy , something less than that 18 - 8 SS you purchased .

[Brion Toss]

Hi again,
T ends are forged, usually. If they are done right, there are no obviously piled-up/fractured bits of metal. If you see such things -- or unevenness, off-angles, etc. -- then it's probably a toggle to walk away from.
Some T ends have a stud that threads into a barrel. Not all are bad, but the type is too vulnerable to corrosion, fatigue, and unthreading.
Fair leads,
Brion Toss

[Douglas]

Ahoy ,,, all the recommendations for designing with SS structural fittings , that I have read about , is to never hang anything structural from a SS welded fitting , and that ALL ss structural fittings should be designed to shed off or drain salt water away from the fitting .

To me this means that any SS , fitting that entraps salt water drops is to be avoided .

It seems that stagnant salt water is the culprit ,,,, like swaged terminal ends , that allow stagnant salt water to collect in the barrels , and rust-corrode the 1 X 19 SS wire inside them .

Some riggers recommend to fill the swedged barrels with various water eliminating solutions , but in reality , this only gives a short margin of delayed ss corrosion .

Personally , I would much rather abide by Brion's advice , " to always build in a reserve of neglect" on your rigging projects , and this also would mean to use SS and design with it properly , to shed salt water , not entrap it .

[paramita]

Originally Posted by Brion Toss

...
T-bars are the most failure-prone terminal, something even Navtec agrees with. You might consider abandoning those T-tangs and installing real ones, especially if you are considering serious voyaging. That way you can go all-Hayn, too.
For...

Thanks for the reply. If I may play one more round of Is This-A-Horrible-Idea/Help-Me-Pick-Between-The-Lesser-of-Two-Less-Than-Ideal-Choices:

To be honest I'm most likely not at a point where I would be ready to retrofit more robust tang son the mast. So I'm wondering if a combination of a threaded t-ball, half a navtec turnbuckle and a hayne marine eye would be any better than just a Norseman T-Ball.

However at ~$116 each for a half a Navtec 500 series turnbuckle I could just go with a regular turnbuckle there for a fraction of the cost. I just liked the 500 series idea since it would be a little cleaner/less bulky gear aloft... Open to suggestions on this train of thought.

This route would provide protection against fatigue on the T-balls with the toggles at the mast connection, and keep all the mechanical fittings Hayn, theoretically keeping every component in the chain with at least the breaking strength of the wire. The down side to this choice (in addition to sticking with the T-balls and added expense) is the only threaded T-balls I've seen are manufactured by Alexander Roberts... which from what I've read (mainly here and on SailNet) I'm not sure thats a route I'm interested in going. Unless there has been any radical, undocumented change in their reputation/practices recently?

Thanks again everybody... just about to pull the trigger on this!

Matt.

edit: I will say I'm skeptical those threaded t-balls even exist, the only place I've seen them is in sailing services catalog and the picture is fuzzy enough I can't really see threads. Could just be a mis-print.

Also I just stumbled upon another potential red herring here. Has any one ever seen one of these in a more tangible form than a sketch. Could they potentially be used to replace an old Navtec t ball?

[Brion Toss]

Hello again,
Do not pull this trigger. If you have already pulled this trigger, un-pull it. Adding a toggle downhill from the T will not reduce load on the bend in the T, and that is where the problem is. Selden and others make T-adaptors for eyes, forks, and HM rigging, but the T's remain.
Alexander Roberts might be a company you want to avoid in general; too many failures of their gear in my experience.
So, if you stay with T's, get the best ones you can, and plan on replacing them at a prudent interval, as determined by route, load cycles, and climate. Or be, you know, rational, and put in actual tangs.
Fair leads,
Brion Toss

[paramita]

Originally Posted by Brion Toss

...Selden and others make T-adaptors for eyes, forks, and HM rigging, but the T's remain...

I have the luxury of no real time constraint to make these decisions. So, as I continue to drag my feet on this matter - can anyone point me in the direction of other companies that make T-ball adaptors? I contacted Selden and they said the fittings I was looking at are not compatible with the Navtec backing plates.

Cheers!

Matt.

[Joe Henderson]

Dear Paramita,

Listen to Brion, you are getting free advice worth it's weight in gold...or non-broken masts.

If you wanted to create and examine a stress raiser in the laboratory, you could do no better than obtain a Gibb/Navtec Tee terminal.

They were marginal in the seventies, have not been improved by the manufacturing facility being shuttled from pillar to post in the last ten years or so as large machine shops bought and sold the rights to the design with not much regard to the end user.

The last lot I received looked like they had been made in some back street hovel in Karachi. I am always suspicious of bent or "Forged" stainless fittings that have been linished all over, they had obviously been worked to within an inch of thier lives.

Gibb managed, through a triumph of development over design, to make the things fairly reliable.

They paid attention to material specs, carefully controlled the pre-heating of the area of the upset forging of the head and flattened the head, gripped the tip and bent the radius of the neck all in one motion on a fairly complex jig.

All this was done by the same couple of chaps for the duration of the production in Warsah. When M.S.Gibb got sold, I asked if the tooling and expertise went with the sale, " Dunno" was the answer!

The manufacturers are aware of the shortcomings of the design, Vis the missive about the terminals not being reccomended for Dyform wire.

This is why the spade type shroud terminal from the same makers was instigated

The last word about the things is best from Johnny Green, late of Sparcraft UK.

They would only use them for checkstays....or stirring their tea... or, at a pinch, as fishing weights.

Then again, Sparcraft would not allow a concentrated loadpath to pass through a weld either.

Solid engineering expertise and experience, you see, just like Brions advice.

Good luck,

Joe.