The new era on chainplates..

[Cheechako]

It's common wording in metal sales.

[Scot McPherson]

Originally Posted by Cheechako

for giggles I went on line and got this quote for silicon bronze bar 1/2 x 2 x 18" , eight of them, I didn't shop around, probably don't need 1/2". SO less than $500 for a whole boat:




That's really not so bad, in fact it makes it a desirable choice

[Stumble]

Originally Posted by Cheechako

for giggles I went on line and got this quote for silicon bronze bar 1/2 x 2 x 18" , eight of them, I didn't shop around, probably don't need 1/2". SO less than $500 for a whole boat:


1900 W. 12 th Ave.
Denver, Colorado 80204
Phone: 1.800.662.0143

Prepared:03/30/17
Prepared For: Prepared By:
Company: Adams, Craig Company: Atlas Metal Sales
Email: Email: jwerner@atlasmetal.com
Website: Silicon bronze, Copper, brass, aluminum, stainless steel, tin, lead and zinc | Atlas Metal Sales
Regarding your request for a quotation on the following products.
Name Description Wt. Unit Price Extension
Saw Cutting 1.00
Silicon Bronze
Flat Bar 1/2" x 2"
Silicon Bronze Flat Bar 1/2" x 2"
x144" cut into 8pc 18" long CDA655 46.00 $10.55 $485.30
Total: $486.30
Please Note:
 Pricing is based upon placement of the entire order.
 The above weights are theoretical and actual weights may vary slightly.


I just did the same for G5 titanium flat bar. You would be looking at around $600 total. But the sizing is slightly different (.498" instead of .5).

[leftbrainstuff]

Originally Posted by Cheechako

I know of no high failure rate, but a lot of high "talk about it rate" .[emoji3] Never knew anyone with a failure, mostly un maintained too. Have seen pics of failures though. Not a ton of those on a google image search either. Some pretty bad looking ones that were removed.
How many boats out there sailing locally do you think have their original chainplates? I don't know but I would guess 90% +?
Not saying they aren't a concern, especially if you are headed off shore. But the tang on your mast lis likely a higher stressed item than your chain plate at 3 times the size.

Crevice corrosion. 3XX Stainless is very susceptible to crevice corrosion in stagnant (crevice corrosion) or high flow electrolytes. (erosion corrosion)

I remember one chemical processing application where 316 SS was losing 1/8" / week from crevice corrosion. I was called into design, engineer, build and install a fix. I implemented a high nitrogen with argon shielding gas weekend weld repair regime until I was able to replace much of the system with HDPE.

The weld repairs and extra filtration reduced the corrosion to 1/8" / month giving me some breathing space to do the major fix. This was a $10M piece of kit that was built by a clueless fabrication business.

All the 3XX and 4XX high chromium steels are fantastic materials that are misunderstood by many.

SS chainplates buried in fiberglass in a boat in seawater is a near perfect environment for this failure mode.

The issue is not the material it is the poor design decisions by people who lack sufficient material and technical knowledge.

[leftbrainstuff]

Originally Posted by Stumble

You can do anything... you can make a mast out of a mild steel rod. But there are very good reasons why you shouldn't is probably a better way to phrase it.

Casting any metal has major concerns when placed in a tension structure. As you noted the principle one is the possibility of inclusions, or tiny air bubbles, inside the molten metal. Got one in the wrong place any you just substantially reduced the strength of the metal. There's are post casting ways to eliminate it a simple a concern, but finding metal bar stock that has been HIPPED, then density tested is functionally impossible unless you are willing to spend far more than the metal costs on post purchase testing.

Cast bronze has another problem. Because of the way that bronze grains form in the casting process it makes the metal incredibly non-ductile. Basically it becomes very very brittle. Even trying to tighten down the chainplate bolts can cause them to crack. Much like using tempered glass panes for chainplates would do (glass sheets are incredibly strong in tension btw, just crazy brittle).

These two together means that with bronze specifically you should not use cast parts for chainplates, you really need forged stuff. The problem with this is that one of the principle reasons to use bronze is that it can be cast so well, so a large percentage of all siliconized bronze on the market is cast, because that's what people expect it to be.

Looking for non-cast bronze is like looking for 6064-T5 aluminum. You can find it if you really want to, but it isn't going to be off the shelf stuff from your local wharehouse supplier. Forged bronze bars ar likely to be special order, small mill production runs. So read that as high cost, seasonally available, and only accessible from some mill on the other side of the US at high shipping cost.

Plate bronze is readily available and is ideal for chainplates where the traditional look of bronze is desired.

There's nothing wrong with cast bronze. It's been in use for thousands of years for swords, cannons and highly loaded components. But it will need to be good quality vacuum casting and not boiled in a pot over a fire. It's getting very difficult to find good casting shops.

[leftbrainstuff]

Originally Posted by neilpride

Yeah the ignorant who say ss is dangerous is me mate, so far so good you can take it with a grain of salt... but its a fact, SS its a poor material in a marine enviroment.. easy to inspect?? cmon probably you point at those inboard chainplates otherwise i can point a dozen of brands where to remove a chainplate call for a painful job.. IP its a example.. I dont found any single record from a composite chainplate failure, the fact that many hig end expensive builders are building in composite plates make me confident about CF chainplates... I dont see any drawback... properly designed and built they are almost bulletproof.... Me think SS has the days counted in the bussines ....

Rubbish.

3XX SS is an excellent marine use material. It's the poor designs and lack of maintenance that cause the issues.

The recreational marine industry wouldn't exist without it.

Look in any marina. There are so many great examples of good quality fabrication and sensible design decisions.

Put it in stagnant sea water or bilge tripe and watch it degrade especially when its loaded.

[leftbrainstuff]

Originally Posted by Stumble

If they cut to true dimensions the variations in weight mean either they work with poor tolerances or it should likely cast. With the variations due to predicted inclusions. How comfortable would you feel knowing that your chainplates vary in strength by an indeterminable amount?

A very small verticle inclusion will have almost no effect of final strength, turn the same one on its side and the chainplate has zero tensional strength.... it's a crap shoot. You could be fine, you could be missing 50% or more of the nominal strength.

We're not talking about diecast rubbish from china or hot rolled low quality carbon steel here.

The silicone bronze bar you can buy is cold rolled bar stock.

Likely cast? Seriously?

[a64pilot]

Originally Posted by Stumble

I just did the same for G5 titanium flat bar. You would be looking at around $600 total. But the sizing is slightly different (.498" instead of .5).

With sizing the same, likely twice as strong as well.
Sized by strength, Ti is likely cheaper.
Ti used to be insanely expensive as the biggest supply is the old Soviet Union, however a few decades ago, the price became pretty reasonable.
I have a Ti bicycle, however I don't think they are made anymore. Carbon fiber is just so much cheaper to produce, and even lighter. So for that application, Ti just isn't the best.
You know I am having my chainplates replaced with Ti ones as mine are encapsulated and inspection is impossible. The difference in cost to have all eight made from Ti as opposed to SS is $1,500.
If mine weren't extremely difficult (expensive) to R&R then I would likely have gone back with SS. Each boat design will of course be different, different best answers.

[Stumble]

Originally Posted by leftbrainstuff

Plate bronze is readily available and is ideal for chainplates where the traditional look of bronze is desired.

There's nothing wrong with cast bronze. It's been in use for thousands of years for swords, cannons and highly loaded components. But it will need to be good quality vacuum casting and not boiled in a pot over a fire. It's getting very difficult to find good casting shops.

And yet we couldn't get cast titanium parts, which are pored in a hard vacuum, past the FAA inspectors without HIPPing then density testing, then individually testing every part. At least not if they were going to be placed in tension. Sure the risk is low, but it is real.

So when dealing with mission and life critical systems, which masts are, I do not think it is acceptable to use untested cast parts. Sure you are probably ok a large majority of the time, but it's that .1% of the time you aren't up that's the problem.

[Stumble]

Originally Posted by a64pilot

With sizing the same, likely twice as strong as well.
Sized by strength, Ti is likely cheaper.
Ti used to be insanely expensive as the biggest supply is the old Soviet Union, however a few decades ago, the price became pretty reasonable.
I have a Ti bicycle, however I don't think they are made anymore. Carbon fiber is just so much cheaper to produce, and even lighter. So for that application, Ti just isn't the best.
You know I am having my chainplates replaced with Ti ones as mine are encapsulated and inspection is impossible. The difference in cost to have all eight made from Ti as opposed to SS is $1,500.
If mine weren't extremely difficult (expensive) to R&R then I would likely have gone back with SS. Each boat design will of course be different, different best answers.

Lol, your chainplates are almost custom designed to ensure they'd would be expensive to make in titanium. The interconnected web of metal with lots of weld surface... it was actually discussed if we should just cut IP chainplates out of plate stock. If the saved labor would pay for the more expensive material costs.

[neilpride]

Originally Posted by leftbrainstuff

Rubbish.

3XX SS is an excellent marine use material. It's the poor designs and lack of maintenance that cause the issues.

The recreational marine industry wouldn't exist without it.

Look in any marina. There are so many great examples of good quality fabrication and sensible design decisions.

Put it in stagnant sea water or bilge tripe and watch it degrade especially when its loaded.

Exactly, put in in the marine enviroment and voila!! thats why in a boat perform poorly... bolts, tangs, screws, pulpits, etc... we can agree that ss is the main reason for loosing a mast.... and thats why this days we can see others materials taking place..