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Old 28-03-2017, 10:40   #46
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Re: The new era on chainplates..

I still prefer my chainplates attached to the outer hull, this way you are pulling on the sheer of the bolts rather than pulling on the threads. It's the same reason the angle irons of my garden beds go on the outside of the box, not on the inside. It's much harder to pull the out from pulling them out and around, than it is when they are on the inside where the bolts can just be pulled out.


I also like galvanized chainplates rather than stainless. They are stronger.
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Old 28-03-2017, 10:48   #47
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Re: The new era on chainplates..

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Originally Posted by minaret View Post
All the integral carbon chainplates I've built had a titanium thimble at the top for the actual rigging attachment point. This means the laminate does not replace the chain plate so much as it replaces the chainplate bolts, imho. This is because GRP is not sufficiently abrasion resistant for a rigging pin, therefore a metal (preferably titanium) fitting is required to be glassed in as the attachment point if you don't want to experience failure due to the pin chafing through the glass. Just replacing your standard SS chainplates with titanium is a simple upgrade which will produce similar results on most older boats. Also, turning down a titanium thimble is very time consuming and difficult, read expensive. If you use anything less than titanium, it's not much of an upgrade. Not likely to see this grade of composite chainplate in mass produced hulls soon. Sticking a carbon chainplate to a ring frame with Plexus and a SS thimble is not much of an upgrade, IMHO. More marketing hype based on what the big race boats are doing; looks the same but isn't.
You only need to use titanium if the laminate is carbon fiber, for a fiberglass hull stainless or aluminium is fine.

Because the metal ferrules are not in tension stainless won't be subject to the type of stress crack corrosion that typically causes chainplate failures. The worst that would happen is the ferrule gets corroded away has to be pulled out and replaced every couple of decades or so. Not that titanium is a bad option, but it isn't necessary.

Cost for one of these ferrules isn't really all that much, it's just a piece of preened over G9 tubing the right size. You do not need to start with a billet, just seamless tubing or pipe depending on size requirements.
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Old 28-03-2017, 10:52   #48
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Re: The new era on chainplates..

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Originally Posted by Scot McPherson View Post
I still prefer my chainplates attached to the outer hull, I have never understood this. External chainplates are only beaten by internal encapsulated plates for the area of them subject to poultices corroion, and intergranular corrosion. The entire back side of the plate is hidden. this way you are pulling on the sheer of the bolts Bolts are weakest in sheer. It works obviously, but it really isn't ideal. rather than pulling on the threads. It's the same reason the angle irons of my garden beds go on the outside of the box, not on the inside. It's much harder to pull the out from pulling them out and around, than it is when they are on the inside where the bolts can just be pulled out.


I also like galvanized chainplates rather than stainless. They are stronger.
The material the chainplate is made from does not determine their strength. It is the combination of material and size. I can very easily design a stainless chainplate stronger than a galvanized one and vice versus.
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Old 28-03-2017, 11:42   #49
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Re: The new era on chainplates..

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The material the chainplate is made from does not determine their strength. It is the combination of material and size. I can very easily design a stainless chainplate stronger than a galvanized one and vice versus.
You could not do so using the same dimensions. You would have to compensate with more material and it would cost more.


Regarding the corrosion on the backside. That's another nice feature of external chainplates. I can just take one off inspect it, get it hot dipped again if needed and rebed it.


It does occur to me though that I prefer boats that are built to working boat standards rather than trimmed out yachting standards. Working style boats are way easier to maintain and I am not worried about scratching them.


How about this...I also like a sacrificial rub rail....how's that sit in your craw?


hehe


Cheers
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Old 29-03-2017, 10:58   #50
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Re: The new era on chainplates..

Chainplate discussions are common here. What isn't often discussed is the tried and true SILICON BRONZE chainplates. Too old fashioned, perhaps?

The only application where it would be problematic would be on an aluminum boat - perhaps they could be isolated enough.

Less expensive than titanium. Immune to the corrosion that is the bane of the best SS available. Easy to machine.

What's not to like?
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Old 29-03-2017, 11:13   #51
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Re: The new era on chainplates..

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Originally Posted by crazyoldboatguy View Post
Chainplate discussions are common here. What isn't often discussed is the tried and true SILICON BRONZE chainplates. Too old fashioned, perhaps?

The only application where it would be problematic would be on an aluminum boat - perhaps they could be isolated enough.

Less expensive than titanium. Immune to the corrosion that is the bane of the best SS available. Easy to machine.

What's not to like?
They can have a lot of perks, IF quality bronze stock can be found, & is used from the outset. Ditto on many alloys of Bronze, Monel, etc. Though there's still that pesky leaking thing, along with some corrosion.
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Old 29-03-2017, 12:09   #52
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Re: The new era on chainplates..

Composite chainplates are extremely difficult to retrofit. They also require expensive molds and tooling, relative to metal chainplates. This makes them uneconomic for many applications and retrofits.

They are also difficult to inspect as structural defects tend to be internal.

Metal chainplates, bronze, monel, stainless or titanium are cheaper and simpler to fabricate and inspect.

Composite chainplates also are generally unsuitable for removable applications. Sharp stress concentrations are the achilles heel of composite structures.

When designed in composite chainplates make sense. Very difficult to retrofit.

I assume the diagram above is only a concept. It does not look like a good composite design at all. No longitudinal stiffeners, poor torsional stiffness and no load spreading into the hull.

Also comments such as ss is a dangerous material are ignorant. The engineering and science is well understood by the engineering fraternity. I started designing and building carbon and kevlar composite structures in the late 80s. It wasn't until the mid 90s until we had enough lifecycle data to properly understand failure modes.

Composites are just another material option. They aren't mysterious or black magic. They have tradeoffs just like any other material selection.

Having spent 30 years in the motorsport sector it is obvious that some parts of the marine industry have little knowledge of composite structures.

It took the motorsport industry more than a decade to really understand structural composites. In the marine sector I suspect some of the poor designs and latent defects will continue for several decades.
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Old 29-03-2017, 13:35   #53
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Re: The new era on chainplates..

Quote:
Originally Posted by crazyoldboatguy View Post
Chainplate discussions are common here. What isn't often discussed is the tried and true SILICON BRONZE chainplates. Too old fashioned, perhaps?

The only application where it would be problematic would be on an aluminum boat - perhaps they could be isolated enough.

Less expensive than titanium. Immune to the corrosion that is the bane of the best SS available. Easy to machine.

What's not to like?
There is absolutely nothing wrong with siliconized bronze for chainplates. But like all materials they have tradeoffs.

1) they need to be resized compared to stainless. No major issue really.
2) you have to used forged bronze not cast. Cast doesn't have the ductility to be used for chainplates and forged siliconized bronze can be hard to find in the right bar stock.
3) it actually isn't much cheaper than titanium, certainly more expensive than stainless.
4) a major issue is that silicon bronze is less noble than passivated stainless steel an far enough away to not be compatible. This means galvanic corrosion is a real issue, and worse it isn't going to occur in the buried hard to inspect portions of the rigging.
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Old 29-03-2017, 13:39   #54
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Re: The new era on chainplates..

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Originally Posted by UNCIVILIZED View Post
Does anyone know where the high failure rate number for stainless chainplates is coming from? And is it taking into account plates being replaced before rigs fall down?

Which begs the question, if someone does even half way decent maintenance on their boat, then why the high chainplate faiure rate? Seems about as smart as driving your car until the tiress are naught but belts with no rubber left, & then blaming the tires/tire manufacturers for them failing. AKA lawyers trying to collect on (obvious) user error.

Thus my query on where the numbers come from, how they're collected, what the circumstances are, etc.
I know of no high failure rate, but a lot of high "talk about it rate" .
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.
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Old 29-03-2017, 13:42   #55
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Re: The new era on chainplates..

Quote:
Originally Posted by Stumble View Post
There is absolutely nothing wrong with siliconized bronze for chainplates. But like all materials they have tradeoffs.

1) they need to be resized compared to stainless. No major issue really.
2) you have to used forged bronze not cast. Cast doesn't have the ductility to be used for chainplates and forged siliconized bronze can be hard to find in the right bar stock.
3) it actually isn't much cheaper than titanium, certainly more expensive than stainless.
4) a major issue is that silicon bronze is less noble than passivated stainless steel an far enough away to not be compatible. This means galvanic corrosion is a real issue, and worse it isn't going to occur in the buried hard to inspect portions of the rigging.
Actually some NE built boats etc have cast bronze chainplates. I too wonder about how good that is as cast structure is not as good in tension especially if there is one small defect in the casting...
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Old 29-03-2017, 14:40   #56
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Re: The new era on chainplates..

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Actually some NE built boats etc have cast bronze chainplates. I too wonder about how good that is as cast structure is not as good in tension especially if there is one small defect in the casting...
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.
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Old 29-03-2017, 16:10   #57
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Re: The new era on chainplates..

Quote:
Originally Posted by leftbrainstuff View Post
Composite chainplates are extremely difficult to retrofit. They also require expensive molds and tooling, relative to metal chainplates. This makes them uneconomic for many applications and retrofits.

They are also difficult to inspect as structural defects tend to be internal.

Metal chainplates, bronze, monel, stainless or titanium are cheaper and simpler to fabricate and inspect.

Composite chainplates also are generally unsuitable for removable applications. Sharp stress concentrations are the achilles heel of composite structures.

When designed in composite chainplates make sense. Very difficult to retrofit.

I assume the diagram above is only a concept. It does not look like a good composite design at all. No longitudinal stiffeners, poor torsional stiffness and no load spreading into the hull.

Also comments such as ss is a dangerous material are ignorant. The engineering and science is well understood by the engineering fraternity. I started designing and building carbon and kevlar composite structures in the late 80s. It wasn't until the mid 90s until we had enough lifecycle data to properly understand failure modes.

Composites are just another material option. They aren't mysterious or black magic. They have tradeoffs just like any other material selection.

Having spent 30 years in the motorsport sector it is obvious that some parts of the marine industry have little knowledge of composite structures.

It took the motorsport industry more than a decade to really understand structural composites. In the marine sector I suspect some of the poor designs and latent defects will continue for several decades.
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 ....
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Old 29-03-2017, 16:17   #58
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Re: The new era on chainplates..

I would not retrofit ??? anything. This counters the whole idea and beauty of the solution.

The fittings are formed during the molding process. They are ONE with the hull. Then they are something different and have added value.

If you want to make a carbon copy of a SS chainplate then you are a craftsman not an artist. Craftsmen build decent boats but it takes an artist to create a beautiful one.

Beauty advances technology. How odd so few people noticed this.

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Old 30-03-2017, 09:01   #59
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Re: The new era on chainplates..

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.
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Old 30-03-2017, 09:47   #60
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Re: The new era on chainplates..

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.
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