Bronze Alloy for Chainplates

Hello all,

I have a 32’ Westsail and would like to replace my 30+ year old stainless chainplates with bronze. Initially I planned to have PTF fabricate a set, but it is fairly cost prohibitive. Instead, I believe I can do it myself, but I would like a bit of help deciding on the particular alloy and form. I know to stay away from “bronze” brasses, leaving phosphor, silicon and aluminum bronzes. Which is best and/or most practical for chainplate fabrication? offers Aluminum Bronze, alloy C95400, in 3/8"x2" and 1.5". The total cost for all of the bronze I need (12ft of 2", 6ft of 1.5") would be about $300.

I have seen people say that aluminum nickle bronze and silicon bronze are good choices for use as chainplates. However, I’m not sure about “aluminum bronze”. It’s specifications are thus:

Aluminum Bronze, C954
Minimum Properties Ultimate Tensile Strength, psi 85,000
Yield Strength, psi 32,000
Elongation in 2" 12%
Brinell Hardness 170
Chemistry Copper (Cu) 83.0% min
Iron (Fe) 3.0 - 5.0%
Aluminum (Al) 10.0 - 11.5%

As opposed to silicon bronze:

Silicon Bronze, C655
Minimum Properties Ultimate Tensile Strength, psi 85,000
Yield Strength, psi 55,000
Elongation in 2" 20%
Rockwell Hardness B90
Chemistry Copper (Cu) 97.0% min
Iron (Fe) 0.8% max
Manganese (Mn) 1.5% max
Nickel (Ni) 0.6% max
Lead (Pb) 0.5% max
Silicon (Si) 2.8 - 3.8%
Zinc (Zn) 1.5% max

Does anyone have experience using aluminum bronze; I want to make sure it is a strong enough metal. I’m not sure if “32,000 psi” for yield strength is enough compared to silicon bronze’s “55,000 psi”. I have found sources for aluminum nickle and silicon bronze sheet, but the total cost is near or above $1000, and I’d still have to cut it, so if this “aluminum bronze” is acceptable, it would be nice!

Thank you for your time!

Ahoy Aaron , of course you have read this, but others might not have .

C61400 - (Aluminum Bronze Sheet/Plate) This aluminum bronze has high strength and good properties at both high and sub-zero temperatures. it can be hardened by cold working and possesses high impact and fatigue strength. Its excellent corrosion-resistance makes it well adapted for process and marine industries. Its use as wear strips and plates reflect its inherit wear resistance properties.

C63000 - (Aluminum Nickel Bronze) This is a nickel aluminum bronze and is widely used when even greater strength than aluminum bronze is required, such as for cam bearings, pump agitators, shafts and aircraft parts.

C65500 - (Silicon Bronze) This copper-silicon alloy is characterized by high strength and exceptional resistance to corrosion. It has the strength and toughness of mild steel, is excellent for both hot and cold working and is readily welded. It is widely used for pole line and marine hardware, welded tanks and unfired pressure vessels.

C67500 - (Manganese Bronze) Basically a tin bronze, manganese is added to serve as a deoxidizer. Its principal characteristics are high strength, toughness and excellent resistance to corrosion. This alloy has important marine applications such as propellers, rudders and non-magnetic mountings.

The above info is from the Alaskan Copper and Brass catalog.

Please let us know, what you find out and why you made that choice.

I did notice on Saraffyn of Victoria, she had cast aluninum nickle bronze chainplates, and as they aged, turned a more silver color, different than the green color of silicon bronze. Roger would know about this, than I .

At the SLM company, we avoided using Bronze with aluminum. Primarily because it was not recommended for underwater use or saltwater environment. You would not consider brass that is copper and zinc. The zinc is really low on the galvanic scale so it will eat away leaving the copper. This is what happens to brass screws that are exposed to the salt air or salt water. Look at where Aluminum is on the galvanic scale.

We also found bronze with aluminum was more brittle than Silicone Bronze. I certainly am not an expert so I suggest you speak to Pete Langly at PTF. I know Pete will tell you what is best even if you do not buy from him.


Douglas and Roger,

Thank you for your responses. I sent PTF an email with the specifications of what I’m looking for. He said they’d take a look and get back to me.

While I’m waiting on that, does anyone know a source for partially-threaded silicon bronze hex or socket bolts? I am only able to find carriage bolts, but on the suggestion of a few riggers, and having seen many cracks emanating from corners of carriage bolt head squares in chainplates, I plan to use a round hole.

Thanks for your time!

Hi Aaron , did you try FASCO fasteners in Alameda, California ?

Usually FASCO doesn’t like to sell to end users, only to wholesale accounts.

West Marine used to get many fasteners from FASCO and they might be able to place a special order to FASCO for you.

I have had to grind off the square corners under the carriage head bolts, to fit in round holes, like on hershoff bronze cleats, so it is easy to do.

At one time FASCO told me they wanted to be the known outlet for the most comprenhensive stock of bronze fasteners, anywhere in the USA.

Of course you can try McMaster-Carr, in California , too.

I am curious about the cracks eminating from the corners of the square holes in the chainplates.

Did the riggers that told you this, tell you which metal they observed the cracks in ? Like was it SS and Bronze , just SS chainplates, or just bronze chainplates, or both ?

Out here in the tropics, marine surveyors recommend replacing SS structural hardware every 10 years, but they don’t have that same recommendation for bronze structural hardware , like forged bronze turnbuckles or bronze toggles .

You have been quite lucky to have your SS structural fittings last 30 years, already .

Did you decide on Aluminum vs Aluminum Nickle bronze , yet ?



Thanks for the response. I looked at FASCO and they do have the parts. I will either set up a wholesale account through them or order form Jamestown Distributors; they stock partially-threaded bronze hex bolts.

The riggers/skippers who complained about squares were all talking about stainless. There isn’t much bronze out there anymore, so it isn’t seen often, but seeing as it doesn’t work harden nearly as quickly I would expect it’s not as much of a problem. Another reason I won’t use square holes is I’m going to do the work myself and I don’t have a hydraulic press!

As for the alloy choice, no, I haven’t decided. I sent PTF an email almost two weeks ago to which Pete responded that he’d get back to me once he’d had a chance to study my drawing. I’ll probably call him later this afternoon to ask about the alloy.

Roger brings up a good point about the corrosion, however I’m not sure about the idea that an aluminum bronze will be more likely to corrode than silicon bronze. That follows logically, but it seems possible that the combination of the aluminum with copper and other elements would change the net corrosion resistance. I know that brasses can dezincify if left in a electrolytic environment for long enough, so that would support it, but I suspect that it’s not necessarily the same for all of the bronzes.

The reason I question is that I’ve read in several places (not the least of which was in the one of the Pardey’s books) that aluminum-nickle bronze is an excellent choice for bronze at or near the waterline (the Pardey’s had the bobstay tang on Talesin made of Al-Ni Brz).

Thanks for your continuing help!


I spoke with Pete out at PTF today and he assisted me in understanding the alloys. Basically, the cast alloys with high corrosion resistance are fine choices for chainplates, so aluminum bronze, aluminum nickle bronze; things in the C95XXX range. The trouble with these bronzes is that they are very hard, inelastic, strong metals, so working with them is trouble. Fabricating using silicon or manganese (wrought) bronze is much easier for its elasticity and bendability; it can be cold worked.

Most of PTFs castings are C955 or C954, aluminum nickle bronze or aluminum bronze. If they are going to be working a piece, they cast it of silicon bronze to enable easier working.

So the 3/8" aluminum bronze stock will work great, the trouble will be bending it. It can’t just be put in a hydraulic press as it’ll crack or shear; it has to be heated. I didn’t ask him about the procedure for heating and working with the metal as that’s his trade! I’m going to dig on the internet to see what I can learn and then decide whether or not I’ll by the stock and make the chainplates.

Chainplates from PTF would be $180/ea, plus $100 for bending, plus $150 or drilling. Boomkin and bowsprit whisker tangs would be $90/ea. So I’m going to check into working the metal myself and doing it for $300 total.

Thank you all for your time!
Aaron N.

I used Rockport Marine in Maine to make mine last year out of silicon bronze, rolled stock not cast. I decided from my reading and asking questions at the time that that would be the stongest and most corrosion resistant way to go, time will tell. I can’t find my bill from them, if I remember it was less than cast ones from PTF. I am pleased with how they came out.

Hi Aaron , glad to hear of your coms with Pete , he and his family were boat builders and sailors , well before he quit and started his bronze casting business, all of them are very knowledgable and conciensious .

There is a process called “Anealing” , that might make bending Aluminum brnz easier , so look into that , too !

The Pardey’s extended their mid-ship chainplates down into the water , as a passive ground for lightning strikes, I did that with my lower bobstay chainplate , who knows , lightning is soo unpredictable !

If you do it right , you could be building in a “reserve of neglect” , that would last the life of your boat , please tell us about your decisions !


PS: Remember that Bronze is much more user friendly , than SS , eventhough your chainplates will be bent to fit hull curvature , you may have to re-curve them another time (Aneeling Them First) if your boat ends up in a tangle of a tsunami , like Calliste was , yes her capshroud midship chainplate needed to be re-bent , after that damage , aneeling was used in that re-bending of Pete’s BCC chainplates , Phew !!!

what did you finally decide to do? I am going to need to replace the chainplates on Shanti sooner rather than later.



I am jumping back and forth between just buying from Pete or getting the material from OnlineMetals. You see, I only have one bend in four of the six chainplates to make, and it’s about 15*, so even if the metal is really tough, I should be able to do that. However, BCC chainplates are much more complicated, and I would not be excited to try to bend 3/8" aluminum bronze stock if it to the BCC specs if it is as hard to work with as Pete says.

If you want to do it yourself, as Pete suggested, spend the $$$ for silicon bronze. Easier to bend, drill and work with. Much more forgiving to a novice metalworker. I’d go that route if I were you as, apparently PTF charges something in the order of $6500 for a set of BCC chainplates. Must be gold plated and titanium cored!

Also, I decided to stick with standard stainless rigging rather than Dux. All of my turnbuckles are WC bronze and I have Sta-lok terminals everywhere, so rerigging with stainless is about $800. Dynex Dux from Colligo came in about $3300.


I had to replace my turnbuckles and wire. That was the reason it made sense for me to go with the new synthetic rigging. When I was considering it and adding the numbers I realized that it was more expensive to go with the Dux because of the cost of all the new fittings. Also since it is a whole new type of rigging I am finding lots of things that don’t fit without custom this and custom that. It has been a bit of a headache. But I should finally have it up in the next few days.

Why have I been reading figures of 1500-1800 for new chainplates from? I have access to a wood shop that has tools that would work with the silicone bronze. But there are still pieces like the cranse iron etc that will need to cast.

Good luck.



You can download PTF’s price catalog and the listing for anything BCC is ridiculous. Of course, they cast chainplates specifically for the BCC hull, whereas the $148 chainplates they’d make for me would be cut down from a standard 31" chainplate, and bent where needed. So I’m sure that accounts for it, chainplates being in the region of $6500 seems high.

But businesses have to stay afloat somehow, so if that’s what it takes for them to turn a profit and keep kicking, all the power to them. It’d be about $1000 for a set of chainplates and tangs for my W32 from them, but he flat out told me that the C954 stock I can get for $300 will do a fine job if I can work it.


Hi Aaron and Gary , for what Pete puts into the bronze BCC Chainplates, you do get a bargin.

They are built to last the life of the boat, then be recycled to another BCC and last the lifetime of that boat as well.

The draw backs are that Pete’s castings are very heavy , and on the ones he did for me , there are iron particles or flecks (maybe manganeese) that show up on the surface, after time.

Knowing what I know now, I wouldn’t hesitate to saw out new chainplates, from Silicon Bronze flat stock or plate, and bend them myself in a v large bench vise, and a 2lb hammer, anneal them if needed.

I did do this with my lower boomkin and whisker stay , chainplates , and have not had any problems with them so far.

What I don’t like about SS or Aluminum structural fittings, is that they give little or no warning, just before they give way or let go .

Thank goodness the boat rocked, just as an aluminum mast head fitting, banged down on the deck next to me, while I was standing there, on the fore deck, Phew , I don’t need another hole in my head !

And as for a cranse iron, I have got some boat photos from the Mystic Wooden Boatshow, of cranse irons that were fabricated out of flatstock bronze, no casting is needed if you think outside of the box !


Hi Aaron,
You mentioned that you can download PTF’s pricing catalog. Do you know where on their website this exists? I looked and could not find it.


I can’t find it either, so maybe they emailed it to me. Email me and I can send it along. Maybe check with them though as I think mine has last year’s prices.


Hey guys, I don’t know where you are getting your pricing from, but I bought 6 chain plates from PTF via Cape George for $650 the lot. That was 18 months ago, now costs have gone up but… I also purchased a lot of stuff then so my price was likely better but even so.

To update you all,

I went ahead and purchased the aluminum bronze stock to fabricate my own chainplates. Total cost for the material was $280, so we’ll see how it goes. The metal will be here this Monday, and I’ll give feedback and photos on how it goes.

Any last minute advice on drilling or working with it? C954.

Aaron N.

Aluminum bronze is very hard, perhaps harder than steel. I would use cobolt bits, a cutting oil and drill press. You selected an excellent material for chainplates - corrosion resistant and strong.

Thanks for the update , Aaron , I have discovered using those “stepped” , cone shaped drill bits.

They are expensive , but worth every penny, that I have spent on them.

I start with drilling a 1/8"th pilot hole with a colbalt twist drill bit, sometimes a 3/16"th , then change to the stepped bit.

I use the stepped bit in a drill press, on SS , and all other metals, it makes a round hole instead of a triangler hole, and they stay sharp longer than conventional twist drill bits.

For cutting SS or other metals I use a Bosch variable speed H/H electric jig saw, just taking it slow and keeping the base metal cool .