Chainplate he'll

[seacap]

I have needed to replace the 1/4" 316 SS chainplates on my boat. They appear to have stress cracks as opposed to crevice corrosion. These plates are 25 years old. They are coming off a 28' 15,000lb Bristol Channel Cutter.

My first shot at doing this was buying flat bar from online metals. They carry aluminum bronze. After drilling and shaping the plates they needed bent to shape. I took them to a local machine shop that does mostly marine work. They broke 3 before giving up. So at that point I either bought more and had the stock Anneled or looked elsewhere. This would have been very expensive.

I contacted Port Townsend founders, as they were known to cast plates and hardware for the Bristol Channel Cutter. I had in my possession the factory construction manual with detail drawings of the chain plates. I asked if the plates were made to factory specs... "Yes, they were".

After 2 months the beautifully made chain plates arrived. They were the proper shape. The holes were in all the right places ect. Just like the drawings except...

The plates were 1/2 inch thick at the top area where the rigging would attach. Now this would not be much of a problem if I was using 1/2 turnbuckles. But I have a 4 year old Dynex Dux rig. The hardware (aluminum deadeyes) are sized for 1/4" chain plates.

So now I am stuck again.

I seem to have a few options:
1) Buy 8 new bronze turnbuckles and fittings for the Dyneema. Cost ~300 each=2400

2) Buy new aluminum deadeyes of a larger size that would fit over the 1/2 inch bronze. I would use some .02" nylon washers for insulation between the bronze and aluminum. Cost~100 each=800

Or, have the plates at the attachment point for the rigging machined down to 1/4". Cost, probably a whole lot cheaper than my other options.

Now my understanding is that manganese bronze is very comparable in strength to SS 316, if not stronger. But the bronze doesn't work harden and fatigue like SS. Or have the problem with crevice corrosion.

So would I be in just about the same or better position with the bronze cut down to 1/4 as I would have been if I was using 1/4" SS?

Thanks in advance for any imput or advise. This really has me bummed for a number of reasons.

Gary

[Brion Toss]

Hello,
And ouch, a series of nasty problems. I am, first, amazed that a shop that allegedly works primarily on marine projects can't bend bronze without destroying it, and further shocked that they didn't pay you for the damage. But what is done is done.
The P.T. Foundry plates might be made to factory spec, but are definitely thicker than they need to be for this boat; 1/2" is the thickness you might see for 7/16" or 1/2" wire. So they can definitely be milled down some.
What wire size is specified for your boat? If 1/4" is the biggest, then 1/4" thick is fine. I realize you are using Dux, but the loads will be the same. If larger diameter is called for, re-check the clearance inside those deadeyes; I have some here in the shop with a gap of about 5/16". It might make for a tight fit on a similarly-sized chainplate, but occasional treatment with Tef-Gel should prevent any corrosion.
The short form is to thin the chainplates as little as possible, to preserve maximum strength. Also, be sure that the transition to the thinner dimension is gradual, so you don't create a stress riser.
Bronze specs are indeed the same as for stainless, according to most sources. Some bronzes, like aluminum bronze, are a good deal stronger than 316 stainless. But note that manganese bronze isn't a bronze at all, but a brass, and therefore vulnerable to de-zycifying. Avoid it, along with the similarly misnamed naval bronze.
Fair leads,
Brion Toss

[seacap]

Well hell...damn iPad auto correct
Brion,
The PTF chainplates are made from manganese bronze. They are stronger than 316.
I have decided to get new rigging pieces instead of milling down to 1/4. The milling would have been expensive because of the convuluted shape of the CP. plus I don't trust the shop that broke the first ones or the other shop here. But I have also purchased some nylon washers used for insulating dissimilar metal parts, and I will also slather on some Tef-gel.

A quick comparison between M bronze...
Minimum Properties Ultimate Tensile Strength, psi 119,000
Yield Strength, psi 66,700

And SS 316
Minimum Properties Ultimate Tensile Strength, psi 89,900
Yield Strength, psi 60,200
So at twice the size needed I guess I have a very large error of neglect.

this manganese situation is very disappointing. I spent good money on "bronze" so I could basically neglect them. But that doesn't seem to be the case now. No doubt they are strong. But the zinc component is troubling. Pete was very concerned that I would be using his chainplates w/aluminum fittings. I didn't understand that at the time. But seeing the zinc content now I do.

I'll just have to keep an eye on them. But what happens if one of my boomkin chainplates is submerged for 22 days on a trip to Tahiti?

Cheers Brion, and thanks for the imput.
Gary

[Brion Toss]

Originally Posted by seacap

what happens if one of my boomkin chainplates is submerged for 22 days on a trip to Tahiti?

Answer: you will have a copper chainplate.
Fair leads,
Brion Toss

[benz]

Hi Gary,

I have 3/8" thick bronze chainplates, and Colligo has a lower deadeye that fits over that with a tiny bit of clearance for tef-gel or Lanocote. I have no room for washers. So you could mill your chainplates to 3/8" (Still plenty thick--my boat is 20,000 lbs), and use those deadeyes. A useful thing is to have them over-drill the holes and then put in a fiber bushing that will accommodate the size pin you'll use (5/8" in my case). That way the bronze pin does not touch aluminum directly. My only problem is having to be careful that the bronze cotter pins on the clevis pins don't get bent to where they touch the aluminum, which quickly causes a small pit.
Good luck,
Ben

[Joe Henderson]

Dear All,

I have been reading this and other related chainplate material threads with interest.

I am not a metallugist and I have no academic qualifications in the fields of corrosion or fatigue analysis.

What I do have is 41 years of dealing with yacht and ship rigging and it's associated fittings - tangs, chainplates, end treatments etc - in both the Northern and Southern hemispheres.

While accepting the strength and longevity in the marine environment of genuine bronzes ( as per those used in Merriman, and the later Lewmar copy of, open body forged turnbuckles. - "Superston" is one trade name that springs to mind. ) I have never been convinced of the properties of widely available "Bronze' stock material. whether in sheet, strip or bar, etc. As per the auther's experiences.

As for the shop cracking the chainplates supplied by the auther for bending. This is a classic dilemma for machine shops all over the world.

"Do we accept the work and all the risks involved with unknown material and not being able to charge the right amount for the work"

Then " How much? All you did was bend a few plates" and such like whining from the owner on presentation of the bill.

As for them having to pay for the damage, you only get that sort of warranty when you have the courtesy to purchase the materials AND the labour from the one place.

I come up against this sort of thing all the time. Friday morning usually " I have got all the wire and fittings, I just need you to measure and swage them for me ( Yeah, because you can buy the wire and fittings from anywhere on line, but you have not paid thousands for a swager or know how to measure and cut ) , Oh, and just put the mast up while you are at it, and tune it, and warrant the whole rig, and I want to go sailing tommorow, I have people coming down for the christening you know, AND I want to film the whole stepping process"

Try this sort of approach with your local Mercedes garage and see how far you get. And, yes, I do consider the world of yacht rigging is on a par, or usually way above the "care and service" you receive from high-end car import salespigs.


I have also never been convinced of the rationale behind the thought process that results in the replacement of stainless steel chainplates with the aforesaid " Bronze"
" Because it is better".

Most of the time the stainless steel chainplates talked about in these threads have given good results for a number of years.

25 YEARS! - in the case of this thread's author's chainplates. ( Show me anything, anywhere that lasts, and still does it's job, for 25 years in the marine environment with little or no maintenance.)

Surely the correct thing to do is replace like for like. i.e. properly specified stainless chainplates where possibly not properly specified stainless chainplates were.

Yes, yes, I know all about the crap quality of stainless steel nowadays, but I can obtain certified G 316 hard rolled plate, with a certificate of conformity, at my local stockists and never use anything else nowadays.

I take the sheet, with a half-legible drawing to my friendly local water abrasive or laser profile cutter's shop ( try gasket manufacturers if no metal cutting shop is close. ) and he cuts them out to about .25 of a millimeter accuracy, including the holes.

I then ream the holes to size and take the completed plates to our local electropolishing shop and they polish and passivate them for me.

A presentable and professional looking set of plates in about a week, and something I don't mind charging the correct price for.

The other problem I find with chainplates is that the owner thinks they are not a maintenance item and turns into a puling child when told to change them!

I usually settle the argument by asking him/her if he/she would be happy to lift the boat by the chainplates. That gets them twitching!

On an associated subject, I seem to remember that there was ahuge amount of Russian manufactured titanium sheet on the market a few years ago - surplus miltary or space agency stuff, I think - I am not saying that this is what is available nowadays, but why go to the bother of using titanium when robust, usually cheaper, more available good old G 316 is so widespread in it's use. I certainly would not use titanium 1x19 wire were it to rear it's head.

And another thing, titanium, while being fairly noble, is further away on the chart from aluminium ( alright, aluminum- Humprey Davey was right first time! ) than G316, so how it is a better option for tangs and corrosion resistance I don't know.

AND while it has good properties in the unworked state - bar for pins etc, - my understanding of the material is that when carelessly worked and formed with under-par tools and a lack of the materials special needs to perfom as expected, you end up with cracked tangs and distorted holes. And do'nt even get me started on welding the stuff.

Rant over,

Regards,

Joe.

[Robbie.g]

+1
Good post Joe.. Could not agree more

[Douglas]

Ahoy Gary ,,, are you saying that your lower boomkin C / P's are made of Pete's Manganese castings ?

I guess if you are really concerned of de-zincification on long passages, you could add sacrificial zincs on those C / P's , like we do on props .

My P T Foundry lower bobstay C / P , is somewhat protected with an attached zinc, because it extends below the water line at all times .

So what was your answer from Pete , when you asked what bronze alloy he was casting your C / P's with ?

BTW , I also have to attach zincs on the lower rudder gudgeon and pintle , especially after I saw pink color showing up on them,,,,, but these were cast in L. A. , at I think "Elk Brass" , but I couldn't guess which alloy was used to cast them !

Since you apparently have remnant Al Ni Brnz plate , you might like to keep a bit onboard for your future voyages , just in case those P T Fndry C / P's de-zincify .

It was Brion who suggested to always build in a " reserve of neglect " , in your rigging fabrication , and that policy has not let me down on my boat .

Cheers ,,, Douglas , BCC Calliste , Jeju-do Island , S Korea .

[Brion Toss]

Originally Posted by Joe Henderson

Dear All,

I have been reading this and other related chainplate material threads with interest.

I am not a metallugist and I have no academic qualifications in the fields of corrosion or fatigue analysis.

What I do have is 41 years of dealing with yacht and ship rigging and it's associated fittings - tangs, chainplates, end treatments etc - in both the Northern and Southern hemispheres.

While accepting the strength and longevity in the marine environment of genuine bronzes ( as per those used in Merriman, and the later Lewmar copy of, open body forged turnbuckles. - "Superston" is one trade name that springs to mind. ) I have never been convinced of the properties of widely available "Bronze' stock material. whether in sheet, strip or bar, etc. As per the auther's experiences.

Hi Joe,
Yeah, these kids with their newfangled gimcracks and doohickeys. Aww, come on, now, the reason that those venerable companies chose those materials is because of the same physics that makes them preferable now. Are you saying that you've seen no higher failure rate with brass than with bronze?

As for the shop cracking the chainplates supplied by the auther for bending. This is a classic dilemma for machine shops all over the world.

"Do we accept the work and all the risks involved with unknown material and not being able to charge the right amount for the work"

Then " How much? All you did was bend a few plates" and such like whining from the owner on presentation of the bill.

As for them having to pay for the damage, you only get that sort of warranty when you have the courtesy to purchase the materials AND the labour from the one place.

But the shop knew they hadn't sold the metal when they agreed to bend it. Experience with marine applications, or any other applications, should be enough to make them aware of the risks involved, for both parties.

I come up against this sort of thing all the time. Friday morning usually " I have got all the wire and fittings, I just need you to measure and swage them for me ( Yeah, because you can buy the wire and fittings from anywhere on line, but you have not paid thousands for a swager or know how to measure and cut ) , Oh, and just put the mast up while you are at it, and tune it, and warrant the whole rig, and I want to go sailing tommorow, I have people coming down for the christening you know, AND I want to film the whole stepping process"

And now we jump an order of magnitude or so, to the blithely insulting customer who knows just how unchallenging and simple your work is, how little skill is needed, and how egregiously you are overcharging for the work. These people exist; I had recent interaction with one of them, and it still rankles. But I am sorry if you actually have to deal with this sort "all the time." It's a happy day when firmly stated policies on pricing and scheduling cause this type of curstomer to go away in search of a different victim.

Try this sort of approach with your local Mercedes garage and see how far you get. And, yes, I do consider the world of yacht rigging is on a par, or usually way above the "care and service" you receive from high-end car import salespigs.

Right, because how hard could it be to sell and service fabulously expensive, intricate machinery like that...
I suspect that there is a higher proportion of incompetent/greedy auto sellers and servicers than yacht riggers. A skillful, fair artisan is a blessing in any trade, though.


I have also never been convinced of the rationale behind the thought process that results in the replacement of stainless steel chainplates with the aforesaid " Bronze"
" Because it is better".

Most of the time the stainless steel chainplates talked about in these threads have given good results for a number of years.

25 YEARS! - in the case of this thread's author's chainplates. ( Show me anything, anywhere that lasts, and still does it's job, for 25 years in the marine environment with little or no maintenance.)

But the question isn't whether there is something impervious to the marine environment. The question is whether or not there is anything better than stainless. Nearly 1/3 of all Boat U.S. dismasting claims are directly attributable to chainplate failure. Nearly all of those chainplates were stainless. The thread author's chainplates hadn't broken after 25 years, but so what? The boat might have lived most of its life in the North, or the Great Lakes, and/or been lightly used, and/or of great quality when new. And even then, they might have been right on the edge of failure. "It ain't broke yet" is not a good approach here. Twice now, apprentices of mine have snapped chainplate bolt ends off by hand, both times while owners were standing by, wingeing about the needless expense we were proposing. Gratifying moments.
If bronze or titanium can be as strong or stronger, can be truly impervious to crevice corrosion, and can have lower fatigue rates, among other virtues, is that a bad thing?

Surely the correct thing to do is replace like for like. i.e. properly specified stainless chainplates where possibly not properly specified stainless chainplates were.

Yes, yes, I know all about the crap quality of stainless steel nowadays, but I can obtain certified G 316 hard rolled plate, with a certificate of conformity, at my local stockists and never use anything else nowadays.

I take the sheet, with a half-legible drawing to my friendly local water abrasive or laser profile cutter's shop ( try gasket manufacturers if no metal cutting shop is close. ) and he cuts them out to about .25 of a millimeter accuracy, including the holes.

I then ream the holes to size and take the completed plates to our local electropolishing shop and they polish and passivate them for me.

A presentable and professional looking set of plates in about a week, and something I don't mind charging the correct price for.

The other problem I find with chainplates is that the owner thinks they are not a maintenance item and turns into a puling child when told to change them!

I usually settle the argument by asking him/her if he/she would be happy to lift the boat by the chainplates. That gets them twitching!

And this is a great way to go, when having stainless plates fabricated. Or any other material.

On an associated subject, I seem to remember that there was ahuge amount of Russian manufactured titanium sheet on the market a few years ago - surplus miltary or space agency stuff, I think - I am not saying that this is what is available nowadays, but why go to the bother of using titanium when robust, usually cheaper, more available good old G 316 is so widespread in it's use.

Why? For the same reason that you wouldn't use robust, usually cheaper, more available, good old improved plow steel; because good stainless makes a better chainplate, all things considered.

And another thing, titanium, while being fairly noble, is further away on the chart from aluminium ( alright, aluminum- Humprey Davey was right first time! ) than G316, so how it is a better option for tangs and corrosion resistance I don't know.

It resists corroding itself, not creating a galvanic cell with less noble adjacent material. And it is, of course, easy to isolate.

AND while it has good properties in the unworked state - bar for pins etc, - my understanding of the material is that when carelessly worked and formed with under-par tools and a lack of the materials special needs to perfom as expected, you end up with cracked tangs and distorted holes. And do'nt even get me started on welding the stuff.

Wait a moment, are you talking about stainless here, or titanium? The above paragraph could, of course, refer to either material. It's all about the skill and responsibility of the artisan. Which closes the circle, here.
Fair Leads,
Brion Toss

PS,
Now that my own rant is over, I might mention that Christian and I will be in your neighborhood in November. Maybe we could visit, and trade rants in person.

[Joe Henderson]

Dear Brion, and Christian

Please, please, please make sure you contact me re. your trip down here.

There is free accomodation and as much beer as you can get down your neck ready and waiting!

To the Harrumph, and in order.

1. I agree, the correct/genuine grade/alloy of bronze is far preferable to any stainless.
I just dont think that the majority of customers ( and stockists ) know enough about the material to ensure the correct supply of the correct material to avoid the sort of problems that Seacap is having.
In the same way that tyres can be described as "round and black' bronze can be described as " brown and shiney". Both those fallacious statements are dangerous.

2. Yes they should have known the risks and refused the work, OR made the owner very aware of the risks proir to accepting the work.
Sometimes the desire to help out a customer outweighs the shops better judgement.

3. I put this clumsily. No, you are quite right, I dont see this scenario ALL the time, just enough to make it seem so!
I sympathise with you on the stroppy customer, I well remember your disertation on "The customer from hell" a few years back on your webpage.
What I have started to do is provide a written quote and scope of works for EVERY job and insist on a 50% deposit up-front and payment in full prior to stepping or substantial completion.
If they cant raise 50% they are probably not serious about the job anyway and they go away!

4.
I actually did try it with a BMW dealer and got asked to leave. I think that there are very few trustworthy large car dealers. " I dont know who said it first, but " Behind every great fortune there is a great crime." True artisans are dying out.

5.
I refer to 1. above.
I agree with you, bronze - correct bronze - fabricated correctly is undoubtedly a better material for chain plates.
33% of dismastings due to chainplate failures - Bloody Hell! we have nowhere near that proportion down here.
I suppose that the old chainplate safety factor of 4 to 4.5 esposed by S&S has been ignored for a few years now in the U.S.
I also love it when a bolt head comes away in your hand. I also love it when you can turn the bolts by hand when the load is off the rig.
There arent that many "great quality when new" boats being built nowadays it seems.
We had a rash of production boats in Australia with U-bolt chainplates, after ten years with poor mastic they snap off at the deck when you give them a twist with a screwdriver!

6.
Sadly not adhered to by many production builders.

7.
The key word here is "Russian". Have you ever driven a Russian car? As poorly reliable as an Italian, but worse-looking.
And see 1. above.
I sailed on a German 30 rater at the America's Cup Jubilee in Cowes a few years back.
It still had the original wrought iron chainplates. Why the owner had left them in-situ during an extensive refit I do not know, he could not give me a good reason either, but there they were, still not breaking.
I kept well clear of them all week and pleaded with him to change them as soon as possible. Who knows, they may still be there.

Another key word here is "Good"
And, if you are not a military contractor buying a lot of titanium with all the checks and balances and quality control measures in place and the paper trail of where the material has come from and it's composition, you can not be sure that the titanium being offered is "good" and you are still in the dark as to the material's suitability for your chosen use.
I am not decrying the myriad benifits of titanium, I just think that most people will get a more reliable job using certified G316.

8.
Fair enough.

9.
More careless typing on my part.
I am talking about Titanium. My understanding is that titanium is more sensitive to being bodged.
The key phrase here is " The skill and resposibility of the artisan".
Sharp bends and poor tooling can result in cracked titanium lower shroud tangs/brackets for one and exploded tip cups during the Hobart for another.

Not for nothing were the tangs, sheave boxes and chainplates on the 12 meter Gretel 2 made from Chrome Moly plate.
And that was with DeHavillands doing the fabrication and construction of the mast and fittings, but they make the space frame of the DeHavilland Beaver, much beloved by bush pilots in British Columbia and elsewhere, out of Chrome Moly tube.
Tough, long lasting and easily repairable, the attributes of most apurtenances of sailing vessels.

I am going round in circles for christmas.

Email me your itinerary and I will collect you both from the airport.

Regards,

Joe.