• Untitled Document

    Join us on March 29rd, 7pm EST

    for the CBEC Virtual Meeting

    All EYO members and followers are welcome to join the fun and get to know the guest speaker!

    See the link below for login credentials and join us!

    March Meeting Info

    (dismiss this notice by hitting 'X', upper right)

Chainplate Crack Cause, Effect, Theory, RFP

Emerald

Moderator
Only on the internet. It wouldn't be easy, but replacing embedded chainplates with anything at all won't be easy.

I know of an Independence 31 that had chain plates replaced. The solution was to abandon the original style where the chainplates were glassed in to the hull with external chainplates that were bolted down the exterior sides. It did not look bad, and makes sense when you think of what would be needed to attempt an original style repair (with confidence.....)

Christian, had you asked about 304 versus 316 on our boats? I know when I dug into this on Emerald, the answer was 304 on anything of our vintage. I assume this would apply to you as well.

And looking at your chainplate, I would have thought some sort of double toggle on that to avoid just what happened and account for minor alignment issues, but I'm far from being a rigging expert, so perhaps some reason I'm missing here for not doing that?
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
I did kill a question posted last night about whether our boats had or have 304 or 316 stainless.

Then I figured I might as well Google it myself instead of expecting someody else to. I withdrew the post because I didn't get very far in finding a good answer.

The 1986-era E38 owners manual just says "stainless rigging."

It is apparently pretty hard to tell he difference in the field. The test is for molybdenum, a "Moly test."

One chemical kit I found is $400. A real tester is $35,000--and most shops don't own one. The world is full of steel mixtures, misidentified materials, advertising copy and outright fibs as to types of stainless and their actual composition.

316, I always thought, had superior corrosion resistance. But how superior?

Like all of us I've had stainless that rusted a bit, or not at all, and I even have had stainless that was slightly magnetic.

We do have a metallurgist on the forum, maybe he can simplify or correct.

I'm having the new chainplate made out of 316. I asked the welder about titanium, and he said "yeah but stainless stretches a little."

How's that for science? So, at my layman's level, I just went with what is known to be standard or comfortable ortraditional.

Edmund Burke, the philosopher, argued against "progress" and for tradition, which he said was too often tossed aside. He was right about the French Revolution, which didn't turn out so well despite a shiny beginning. Burke pointed out that farmers stick to known farming practices, rather than radical newfangled production ideas, because although a crop may produce only mediocre results using the usual methods, an untested method may fail entirely--and everybody would starve to death.

I don't know that Edmund Burke is commonly used as an argument for 316 stainless. And in fact the guy was a reactionary jerk. But then, politics is strictly forbidden here, except in the case of stainless.
 
Last edited:

Emerald

Moderator
It seems I went through a similar "learning" experience when I redid Emerald's rigging. I got into a proverbial pissing match with what was supposed to be a great rigger here in Annapolis. I was really lucky, I was able to get a note from Bruce King regarding my issues, and that's what it finally took to get the job right, and I must admit it was kinda fun watching the rigger go speechless when confronted with an expert versus just some dumb boat owner..... Bottom line that I took away from it was assume your rigging was done in 304, and replace it with 316, but go up one size in the process to account for the loss of strength in the 316 - it is more corrosion resistant, but to do so changes the alloy at the expense of strength, so upsize it all. Lovely, ain't it?
 

ignacio

Member III
Blogs Author
I initially considered replacing with 316. Aside from my rigger and the yard informing me that my original chain plates were 304, assuming that they were was a precautionary assumption I was willing to make for metal of that vintage. Evaluating what they were made of also wasn't useful to the task at hand. The crack on the bow chainplate was plainly visible and had to be replaced. As I pulled them all out, more issues were revealed. Could 316 have worked for another 40 years? Probably, but even 316 will corrode in the absence of oxygen. The cost after labor to machine and polish 316 got pretty close to the cost of titanium - within a hundred bucks if memory serves - which doesn't need polishing like 316. Crevice corrosion doesn't happen with titanium. I replaced all of them, and most of them pass through the deck, where stainless (including 316) loses its corrosion resistance first.

Since we're talking about decades of use using either material, for me it came down to estimated length of ownership and use: Those extra hundred bucks seemed worth the investment. Who knew metal selection could stir so much excitement?

An interesting article published around the time I was doing this project:
http://www.allatsea.net/the-worst-possible-chainplates/
 

bgary

Advanced Beginner
Blogs Author
On reinstallation of the new chainplate, I plan to over-drill the transom holes slightly, so the plate can align naturally.

Counter arguments invited.

No counter-argument, but don't over-drill them much. You want to be sure that the full bearing surface of the thru-bolted fastener mates up with the surface of the hole. Otherwise you can get point-loading at each fastener which is bad in a shear-loaded connection.

$.02
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Point taken, Bruce.

Titanium is high class.

Here is Frank Gehry's bowsprit and imaginative binnacles. He sheathes buildings in it, including the "sails" of Disney Hall. Gehry's curves are said to be inspired by affection for yachting.

1-FOGGY helms.JPG1-Foggy bow titanium.JPGdis hall.jpg
 

ignacio

Member III
Blogs Author
Isn't the skin of the Disney Concert Hall made of stainless though? I think I remember reading that the initial mirror polish of the building caused issues with nearby traffic and buildings, solved with a little sanding. Beautiful building though. But that binnacle makes me think something will eventually get caught on it. Thankfully, our approach with E-boats can be a bit more utilitarian, at least in structural elements and material selection.
 

u079721

Contributing Partner
Hey, isn't anyone going to suggest that what you really need is 316L grade stainless steel?

Just kidding....but in my work as an industrial chemist and process safety "expert" there were many times when even 316 wasn't good enough. Sometimes we went with 316L, sometimes with a nickel based alloy called Hastelloy. All of these have less mechanical strength of course, but that just meant we made the walls thicker. The rule of thumb was to avoid chlorides whenever possible. And if you do have to have chlorides present in the formulation, for goodness sake don't heat it!

Having a rigger suggest that 304 is good enough, since "that's what the boat came with", would seem to be a pretty silly argument when faced with cracks and failures of the original rigging.
 
Last edited:

Grizz

Grizz
Cascading split backstay?

Since this thread has rolled into its 3rd page, perhaps now's the time to insert this small nugget into the dialogue: this thread has been helpful, if only to guide in the material needed for the tangs, plural, that'll be mounted sometime this spring to form the pair of transom attachments for the replacement of the OEM Navtec backstay.

a pair of locations and orientations have been penciled onto the transom; blocks, low friction rings, cam cleat locations and line diameter and length have been transposed to lists. A rudimentary mockup has been rigged, creating dimensions for shortening the backstay. A working understanding of how to calculate and express purchase ratio has been acquired. The difference between 8:1 and 24:1 can be explained and used to illustrate where the 'Jesus Load' resides and what the load should be at the cam cleat once the reductions occur.

It's not known at time of writing what the mound of sheet laying in the cockpit will be when the backstay is fully trimmed. It could look like Medusa's Head. Time will tell.

No holes have been drilled, yet, but they will be drilled. The backstay hasn't been removed, measured or shortened, but it will be. And it's hoped that in late April there'll be an adjustable backstay system that represents early 21st century systems. And a used, rebuilt, Navtec listed on eBay!


And all this to induce perhaps 4"-6" of rake into a very stiff mast. And make it easier for The Cockpit to trim/ease the backstay, quickly (not helm!). And open up the center of the helm seat, a 'comfort only' component, moving the backstay outboard to 2 points port/starboard.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
As a part of the planning process for a cascading BS adjuster, a sail on an E-33RH would be instructive. Their stock setup was adjustable from either side of the transom.
 

Rick R.

Contributing Partner
So.......

This is enough to make one concerned about the chainplates.

So, what is the consensus here regarding grades of SS, assuming one doesn't intend to use titanium?
 

ignacio

Member III
Blogs Author
This is enough to make one concerned about the chainplates.

So, what is the consensus here regarding grades of SS, assuming one doesn't intend to use titanium?

Don't know about consensus, but Brion Toss recommends 316L polished to a mirror finish if going stainless (article below). Steve's comment above (post #32) suggests that the lower strength of 316L compared to 304 might require upsizing to compensate for the loss of strength, but by how much I couldn't say.

Brion Toss article
http://www.allatsea.net/the-worst-possible-chainplates/

Jamestown Distributors SS grades properties comparison
https://www.jamestowndistributors.com/userportal/document.do?docId=536

The Jamestown article doesn't provide very many metrics on tensile strength, etc..., but there's other places online that have similar charts with something more precise than "good, excellent, and best" to rate stainless grade properties.
 
Last edited:

Guy Stevens

Moderator
Moderator
Don't upsize automatically

You would do much better to actually figure out the loads and the safety factor on the rig and the boat and make sure that you have the right rigging to support those loads.

I have seen way way too many boats that have rigs that are untunable, and or unsafe rigging from upsizing to a bigger wire.

This is not a simple solution that you can apply.

Guy
:)


It seems I went through a similar "learning" experience when I redid Emerald's rigging. I got into a proverbial pissing match with what was supposed to be a great rigger here in Annapolis. I was really lucky, I was able to get a note from Bruce King regarding my issues, and that's what it finally took to get the job right, and I must admit it was kinda fun watching the rigger go speechless when confronted with an expert versus just some dumb boat owner..... Bottom line that I took away from it was assume your rigging was done in 304, and replace it with 316, but go up one size in the process to account for the loss of strength in the 316 - it is more corrosion resistant, but to do so changes the alloy at the expense of strength, so upsize it all. Lovely, ain't it?
 

Alan Gomes

Sustaining Partner
As a part of the planning process for a cascading BS adjuster, a sail on an E-33RH would be instructive. Their stock setup was adjustable from either side of the transom.
As a prof. who has attended his share of professional conferences, I can attest to the large number of "cascading BS adjusters" in academia. Perhaps this is so for other occupations as well. :rolleyes:
 
Last edited:

Guy Stevens

Moderator
Moderator
Ti go with Ti

Go with Titanuim grade 5 certified.

Call John Franta at Colligo Marine. He does a great job with them, and we have installed a lot of sets made by him in a lot of different boats, some of them even Ericsons! :egrin:

Lots of those cracks in the chainplate photos posted are not flex cracking or work hardening. Those cracks follow a significantly different path and look different.

I am in the middle of nowhere looking at this on a phone, so I didn't look at all of the photos, but most of them I saw here were Crevice corrosion of Stainless steel starting from a machined (drilled) surface. This is how most of them fail, and is very common for boats of this era. (All of our Ericsons with SS chain plates are on borrowed time). Industry standards for both the rigging and the chainplates (they are made of the same materials remember?) are that they should be replaced at 10 years. (now some of this is CYA from the companies that manufacture rigging wire, and it is very dependent on the location where the boat is being stored and sailed. But 40 year old chain plates are well outside of the limits. )

Guy
:)
 

Guy Stevens

Moderator
Moderator
304 vs 316 detection

Oh and by the way you can detect 304 vs 316 by using a small magnet on a string. 304 is slightly magnetic

Simply place the magnet on the rigging, if it sticks a little and you can see it move the magnet it is 304, if not 316.
This is easier than even this description makes it sound.

Guy
:)
 
Top