Chain Plate Roundabout
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.
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