Critical Standing Rigging Part -- Re-Use Old or Go New?

[rardiH36]

I can't decide what is best in this case: Re-use my existing OEM important standing rigging part. Or go with the new part that I have bought but from just a visual look doesn't quite match the OEM.

Background is that I read on these forums a couple of years ago about failures of U-Bolts that act as "chain plates" connecting standing rigging wire to the deck or toe rail ... etc. My two 35 year old U-bolts that attach my split backstays to the toe-rail near the stern seemed to fall into the category. One of these is shown in the attached photo. Since Hunter installed them without any isolation between the aluminum toe rail, galavanic corrosion was evident. I was worried about unseen crevice corrosion within the u-bolt metal.

Before removing the 35 year old u-bolts, I ordered a couple of Wichard #6542 replacements that had the same 1 3/8" span between the centers as my existing OEM u-bolts. The strength specs are:

Working load - 2400kg (= 5,291 lbs)
Breaking load - 4800kg (=10,579 lbs)

Upon removing my OEM u-bolts (which as an aside was quite a task due to limited access and my body being too big), I discovered a couple of things:

1) Even though the distance between the centers of the two "arms" are the same 1 3/8", the bolt diameter of the OEM's is larger than the the Wichard's I bought;

2) The OEM's upon removal looked GREAT! No crevice corrosion evident at all. Actually no rust or pitting I can see. 35 years on the boat? Amazing!

Also attached is a photo of the old OEM and the new Wichard side-by-side. All I did to the OEM was soak in acetone for a while to remove the original caulk/sealant. Although the Wichard legs are shorter, still plenty long enough for my application. The amount of thread of the OEM part that Hunter installed was about 2" longer than necessary.

So my conundrum is:

- Now that I know that the OEM u-bolts seems just fine, should I just re-install them? After all, they do have the larger bolt diameter. But I suspect that the OEM's are (say) 316 SS with no "hardening".

- Or do I install the Wichard's that I bought. Even though the bolt diameter is somewhat smaller, I believe that the Wichard's are tempered/hardened and just might have equal or even higher load specs than the OEM's.

My inclination is to install the new ... maybe because I bought them many months ago and now no chance of returning!

 

[Joe]

Since you're gone the trouble to remove an inspect, after incurring the expense or replacing... I would install the new ones.

However, of greater importance to any kind of rigging to deck connection is to insure there is a proper backing plate for the hardware. The old Catalina 27's, for instance, had similar u-bolts attaching the four lower shrouds to the deck... after owner complaints of deck buckling in the area (probably from over tensioning the backstay, heh, heh) a retro fit kit was offered that was essentially a large plate replacing the washers, that spread out the load.... So... just saying.. while you've got your head down there.. take a look at how the load is distributed under the deck and see if any improvement is necessary.

 

[woodster]

is this an optical illusion the one on the right seems smaller than the one on the left in diameter

 

[Ron20324]

is this an optical illusion the one on the right seems smaller than the one on the left in diameter

That's what the OP says.

 

[woodster]

That's what the OP says.

sorry about that i just reread the post and yes he did...... i personally would try to go with the same size not smaller dia...the engineer that rated the hardware originally knew what he was doing and it lasted 35 years

 

[rardiH36]

Going back to my original post (which might have been a tad too long),I guess that my real question is whether the Wichard u-bolts working/breaking load specs are sufficient for my application.

Working load - 2400kg (= 5,291 lbs)
Breaking load - 4800kg (=10,579 lbs)

Joe: Thanks for the backing plate head's up. Since my u-bolts are mounted through the horizontal extrusion flange of the toe rail, that in effect provides the stress distribution function. I do have some SS 1" x 1/8" SS bar stock I can cut and drill holes through for added stress distribution.

 

[DHaranSailor]

I am with Joe. If you already have it dis-assembled and the working loads match I would move to the new hardware if it was my boat.

 

[Gunni]

This is really a question for a rigger, however I am sure they would tell you that 35 years include enough duty cycles on that fitting. Joe is referring to an under-deck backing plate that distributes the rigging load across more of the toe-rail structure. In this case it would be similar material - stainless. That would be an strength improvement.

 

[JohnShannon]

Golly what a problem. Bear in mind that the area of the bolt increases very rapidly with diameter. So the old bolt even if it is executed in inferior material might have more strength due to larger area. As said by others, " you might want to seek professional help"

 

[rardiH36]

This is really a question for a rigger ...

" you might want to seek professional help" ...

John/Gunni:

Good suggestion. The rigger's shop is just around the corner from me. Easy to bring the old and new and ask for their recommendation. I paid a couple hundred dollars a couple of years ago for a rigging safety survey so maybe there is enough goodwill in the relationship to get some free advice.

John: As to "you might want to seek professional help": My wife also has suggested that to me more than once. Even before I owned a sailboat!

 

[centerline]

Going back to my original post (which might have been a tad too long),I guess that my real question is whether the Wichard u-bolts working/breaking load specs are sufficient for my application.

Working load - 2400kg (= 5,291 lbs)
Breaking load - 4800kg (=10,579 lbs)

Joe: Thanks for the backing plate head's up. Since my u-bolts are mounted through the horizontal extrusion flange of the toe rail, that in effect provides the stress distribution function. I do have I can cut and drill holes through for added stress reduction.

with a split back stay, you would have two u-bolts sharing the load... so you have a combined working load of over 10,000lbs, and a minimum breaking strength of over 21,000 lbs... on the back stay.

the back stay has the least amount of tension on it of all the standing rigging, due to the geometrics of it... the anchor point being further away from the part that it is holding.

you should have no worries for the next few years until corrosion catches up to it....

the best way to visually check for any pitting or cracks in the original parts are to soak it in a strong acid solution (muratic) for an hour... this will eat all the rust away from it and leave it clean for inspection...

to further your inspection, you can go to the welding shop and get a crack detector kit which consists of 2 spray cans, one of dye, the other is a reveal fluid...

with a clean dry piece of metal, you spray the dye on and let it set a few minutes... then you wipe it clean, very clean, and let it dry for awhile.... then clean it again.

then spray the reveal fluid on it and let it set for 15-20 minutes.
any permeation's such as pitting, or cracks in the metal will show as a very bright red spots or fracture lines, very visible to the naked eye..

 

[caguy]

Since you're gone the trouble to remove an inspect, after incurring the expense or replacing... I would install the new ones.

However, of greater importance to any kind of rigging to deck connection is to insure there is a proper backing plate for the hardware. The old Catalina 27's, for instance, had similar u-bolts attaching the four lower shrouds to the deck... after owner complaints of deck buckling in the area (probably from over tensioning the backstay, heh, heh) a retro fit kit was offered that was essentially a large plate replacing the washers, that spread out the load.... So... just saying.. while you've got your head down there.. take a look at how the load is distributed under the deck and see if any improvement is necessary.

I don't know what they did to retrofit yours but on mine the put in four 2" x 2" x 4" 1/4" thick ss angle iron. It looks like way overkill. Here is a picture of it.

 

[rardiH36]

CaGuy:

Yes I see the angle reinforcement.

But what I really observe in your pic are the curtains. The fabric and workmanship blend in wonderfully with the interior space and add a positive ambiance without being at all overwhelming. Good choice.

Who is your interior designer?

 

[Ron20324]

If you're going to replace it, at least buy the same/right size, and not use what just happened to be in the tool box. West, page 1019 for starters.

 

[Joe]

I don't know what they did to retrofit yours but on mine the put in four 2" x 2" x 4" 1/4" thick ss angle iron. It looks like way overkill. Here is a picture of it.

Yep.... that's the fix.... That kit is available through CatalinaDirect.com (also Catalina factory parts dept, I think) for $162.

Better safe than sorry.

 

[rardiH36]

If you're going to replace it, at least buy the same/right size, and not use what just happened to be in the tool box. West, page 1019 for starters.

Ron:

Thanks for your time to investigate part alternatives. I did the same before I bought the Wichard's. What I found though is that most SS u-bolts, like the 5/16" ones (West Marine's max size) had much less working load ratings than the Wichard's. Even the typical generic 3/8" diameter marine grade u-bolts had less strength specs than the Wichards.

A main requirement is my need to have 1 3/8" center-to-center spacing between the two u-bolt legs. I don't know where Hunter got their 3/8 diameter u-bolts in 1980, but these days anyway 1 3/8" spacing generally equates to a 5/16 (8mm) bolt diameter. The 3/8" (10mm)'s that I have seen on line have a greater spread between the arms so they can't fit into my existing holes. One exception I found was a 10mm marine grade U-bolt made by Anzor (Australia I think). Their model S413 looks to fit the bill in respect of distance between the two legs. But SWL is 3600 lbs vs. the 5291lbs of the Wichard's.

I will admit though that I didn't initially notice that my 1980 u-bolts were 3/8". So I was surprised yesterday when I removed them that my new Wichard's diameter was a smidgen smaller! Hence my quandary.

 

[rardiH36]

Centerline:

Thanks for the info. Particularly your observations about the split backstay sharing the load and that the strong angle reduces the the stress. My gut and research and a few other responses suggest that I will be just fine with my new Wichard's. (But also I am leaving in a few minutes to show/ask the rigger for his opinion.) Even if my old u-bolts did pass the dye test, they nonetheless already have had 35 years of San Francisco Bay sailing and exposure to the elements. Some fault with them might be just around the corner. I am a little gun-shy after my head-stay's double jawed toggle ruptured a couple of years ago. That was just a few months after a professional rigger spent a minute or two staring the assembly as part of a rigging safety survey I commissioned. Pic below of the ruptured part.

I did further clean my removed u-bolts. With Maine Sail's favorite "Spotless Stainless". No rust left at all ... not that there was much after I soaked them in acetone to remove the caulking sealant.

 

[Gunni]

If it makes you feel any better, I just had the riggers go through my standing rigging and replace everything with new. 11 years use.

 

[shemandr]

I'd like to pose a question to those knowledgeable about metallurgy: Is there any way to assess the degree of work hardening of a piece of stainless? Would it make a difference if it was cast, forged or whatever. It would seem to me that work hardening would be an issue after 35 years, but then I don't even know if stainless work hardens.

 

[rardiH36]

:dance:

Thanks everyone for input.

Just thought to give the thread a conclusion:

This afternoon I showed the local rigger my new Wichard u-bolts. He referred to chart or two. Then opined that the parts were right at the cusp of being robust enough. So sort of a "maybe not". What I hadn't considered is that the tension direction from the split backstay isn't straight up. So this induces an off-center torquing stress to the u-bolt. Therefore better to oversize.

He directed me to his used parts section. In particular a couple of much larger diameter u-bolts that had been on a new boat but then was determined not to be ideal for the owner's requirements. And yes the pieces did look virtually new. Price was good. I bought. The spacing between my newly acquired u-bolt legs is greater than my existing holes. But the rigger pointed out it's no big deal to drill through the aluminum toe-rail and the hull/deck FRP flange.

Anybody in need of some brand new Wichard u-bolts? If not, I do have an idea or two in respect of my own boat.

To the boat tomorrow to complete the project.