Is naval Brass= Tobin Bronze

[chuckm]

Searching for silicone Bronze, it's out there but expensive and shipping. Is Naval Brass the same as Tobin Bronze? Needing 5/8 rod. Many have accepted Nicol Bronze, Tobin Bronze. Tobin Bronze is an excellent rod for securing lead ballast. Anyway a good source of Naval Brass is available to me in the immediate area. Galveston Bay. I would suspect that Naval Brass to be a little softer, that would be advantages when working/threading. Does any one know? The Marine Industry Sales person say's its the same.

[Mike Vogdes]

Jamestown distributors has 5/8" rod in silicon bronze
http://www.jamestowndistributors.com...ne=1&page=GRID

[Thorne]

I'd say not exactly the same -
http://chestofbooks.com/reference/He...in-Bronze.html
http://www.diversifiedmetals.net/nav...FQENDQodA0-neA
http://www.diversifiedmetals.net/silicon-bronze.htm

But depending on your use of the rod, it may not make much of a difference.

Duckworks has both SB and Naval Brass -
http://www.duckworksbbs.com/material.../rod/index.htm
http://www.duckworksbbs.com/material.../rod/index.htm

Wikipedia sez:

• Naval brass, similar to admiralty brass, is 40% zinc and 1% tin.

http://en.wikipedia.org/wiki/List_of_copper_alloys

[johnw]

Actually, I think they are the same. If memory serves, L. Francis Herreshoff gave the composition in The Common Sense of Yacht Design, and it was the same as naval brass.

It also looks like it here:

http://www.thefreedictionary.com/Tobin+bronze

[chuckm]

Thanks all. That' the answer I wanted. I can get for a good price and local. It's huge international Marine constuction firm, and they sorta chuckled when I told them that all I needed was 15-20 feet. There'r used to mega deminsions and by the hundred's of feet. But here's a trueism: everybody likes to help one-off single man boat-builders.

[JimConlin]

I don't think they're the same.
Naval brass is about 40% zinc.
Tobin bronze contains tin and maybe iron.

[PeterSibley]

http://en.wikipedia.org/wiki/List_of_copper_alloys

From Thorne's link naval brass is a high zinc alloy ,39% zinc .I would definitely NOT use it as keel bolts .

It's pretty close to manganese bronze , a very good material were lots of strength is required but not for below the water line (except propellors ).

[Plumbtex]

You might try here as a source for bronze, brass and maybe info
http://www.farmerscopper.com/

[AHall]

If Silicon Bronze is what you are after, than you need to speak with Atlas Metal Sales in Denver CO. they advertise in Woodenboat, have great prices and excellent customer care. They will ship whatever you need ups.

Buy extra because if you are a boat guy, you will find uses for the scraps.

Good luck,
Andy

[Canoez]

I don't think they're the same.
Naval brass is about 40% zinc.
Tobin bronze contains tin and maybe iron.

Jim's got it - small amount of iron and a small amount of lead, too. IIRC, what's referred to as "Naval Brass" actually is classed as a bronze. Naval brass is an unleaded brass.

[JimConlin]

... and after salt water gets done with the zinc, you have a copper sponge that's about the same consistency and strength as toasted white bread.

[Canoez]

... and after salt water gets done with the zinc, you have a copper sponge that's about the same consistency and strength as toasted white bread.

Which is why silicon bronze is recommended for the application, no?

[chuckm]

OK the zinc is bad, what of Tobin Bronze. OkOK Just get silicone Bronze...

[johnw]

http://en.wikipedia.org/wiki/List_of_copper_alloys

From Thorne's link naval brass is a high zinc alloy ,39% zinc .I would definitely NOT use it as keel bolts .

It's pretty close to manganese bronze , a very good material were lots of strength is required but not for below the water line (except propellors ).

LHF spec'd it for keel bolts. Maybe he was wrong. I'm not an expert.

[chuckm]

Well here's the deal, my build is a tralier sailer. She's big so maybe in the water 1/2 of the year. Can I use these newer metals like Nichol aluminuim bronze? They are less expensive. Does any have info on this ToughMet, it is a copper nichol alloy.

[Peerie Maa]

From the Wiki link

Naval brass (ASTM B21) Cu 60.0, Zn 39.25, Sn 0.75 Annealed 22 56 40 90 Resistance to salt corrosion

The tin protects the alloy from dezincification.

[Bob Cleek]

If it is BRASS, it's an alloy primarily composed of copper and zinc (usually around 40% zinc).

If it is BRONZE, it's an alloy primarily composed of copper and tin.

"Phosphor bronze" is bronze with some phosphorus in it. "Silicon bronze" is bronze with some silicon in it. And so on. There are hundreds of both brass and bronze commercially available alloys. Many of these have "brand names," like "Tobin bronze" (from the Tobin bronze company) or "Everdur," a trade name for silicon bronze.

The LAST thing you ever want to use for keel bolts is BRASS. As said above, under the water, the brass will "dezinc," with the zinc turning to zinc oxide powder, leaving a very weak (microscopically "swiss cheese" looking) piece of copper. Don't go there.

Brass really doesn't belong on any boat, except when used for polished trim and accent pieces. Brass lamps, clock and barometer cases, binnacles, door knobs, grab rails and that's about it. (Bronze bells are WAY better sounding than brass ones, but hard to come by these days.)

[johnw]

Think I'll go with Nick on this.

[Canoez]

One of the other considerations - particularly when thinking about mounting is the physical strength. Silicon Bronze has very good tensile strength in comparison with other bronzes. Bronzes can also be a bit on the brittle side, too.

[donald branscom]

Searching for silicone Bronze, it's out there but expensive and shipping. Is Naval Brass the same as Tobin Bronze? Needing 5/8 rod. Many have accepted Nicol Bronze, Tobin Bronze. Tobin Bronze is an excellent rod for securing lead ballast. Anyway a good source of Naval Brass is available to me in the immediate area. Galveston Bay. I would suspect that Naval Brass to be a little softer, that would be advantages when working/threading. Does any one know? The Marine Industry Sales person say's its the same.

There is no such thing as silicone bronze.
There IS silicon bronze.
Silicon adds hardness to the metal
Just like it does to aluminum.
Many times sales people have NO IDEA what they are talking about.
They just sell things.


Lead in any metal helps make it easier to machine.
302 stainless has more lead in it for that very reason.
Home Depot just does not know about that yet. To them stainless is stainless.
If we take the lead out of all metals it will just cost more to machine.
They took all the brass fitting off the shelves because of the lead fear.
Now the price is double? For NOT putting in the lead?

If your water goes past a 302 stainless fitting, how much lead
do you think will get into your blood?

Engine cases have about 18-20% and pistons have 22% . It also keeps expansion rates down when the pistons get hot.

Do not get me wrong.... It is good to clean up the environment but lets get reasonable.
There was no reason to charge MORE for the brass fittings.
It is all the brass shell casings being used in the wars that is costing us.

[chuckm]

Ok be easy on me; I've already had two glasses of wine (cheap), and I flunk and had to retake In-organic chemistry twice,many years ago, understand.. so I want BRONZE, with either Zn or silicone in it. There is no way around this. Just ask for silicone Bronze and be done with it. $$$$

[Thorne]

Chuck at Duckworks is a good guy and deserves your $$. Make the purchase online before ya sober up, big guy...

[JimConlin]

..... so I want BRONZE, with either Zn or silicone in it. ...

You don't want either.
Zn is the stuff that disappears by electrolysis if there's copper or lead nearby.
Silicone is for boobs and bathtubs. [didn't dare post a pic]
Tin makes copper a bronze and a little silicon makes it stronger.

[PeterSibley]

From the Wiki link
The tin protects the alloy from dezincification.

Interesting ! Is it possible to offer an explanation I would understand ?

[Bob Cleek]

Interesting ! Is it possible to offer an explanation I would understand ?

Nope. He hasn't a chance. LOL

Tin doesn't "protect the alloy from de-zincification." The tin is there instead of zinc, which is what makes the alloy bronze instead of brass.

For some, I fear, there just isn't any hope, Peter.

[johnw]

Nope. He hasn't a chance. LOL

Tin doesn't "protect the alloy from de-zincification." The tin is there instead of zinc, which is what makes the alloy bronze instead of brass.

For some, I fear, there just isn't any hope, Peter.

For Tobin Bronze, which is the same as naval brass, both tin and zinc are in the alloy. LHF thought highly of it.

[ssor]

This site provides a very good discription of most of the copper alloys.
http://www.anchorbronze.com/

[Bob Cleek]

For Tobin Bronze, which is the same as naval brass, both tin and zinc are in the alloy. LHF thought highly of it.

Alloys are combinations of all sorts of metals. General categories like "brass" and "bronze" are classified by the primary components. The primary components of brass are copper and zinc. The primary components of bronze are copper and tin.

"Tobin bronze" is a true bronze. Yes, it does have "both tin and zinc" in the alloy, but the amount of zinc is inconsequential.

Tobin bronze is made of the following:

Copper 82.67 percent
Tin 12.40 percent
Zinc 3.23 percent
Lead 2.14 percent
Iron 0.10 percent
Silver 0.07 percent
Phosphorus 0.005 percent

The three percent zinc isn't particularly problematic in the marine environment and it is said that the other metals in combination further inhibit corrosion of the zinc in this particular alloy.

Brasses, on the other hand, have much higher percentages of zinc. Even admiralty brass contains 30% zinc with 1% tin to inhibits dezincification to some extent. Other brasses intended for marine use can contain as much as 40% zinc. Muntz metal, also called duplex brass, is 35–45% zinc. Beta brasses, with 45–50% zinc content are used for casting.

[Varna]

In Nigel Warrens 'MetalCorrosioninBoats' he states a brass with below 15%Zn content will 'usually' not dezincified, and can be succesfully used underwater 'If' it is inhibited with trace arsenic. But how to know it is the correct alloy from the supplier? Esp in these days of such fine china style integrity. Warren also doesn't at all in anyway recommend any brass for ballast.
You could probably get away with fudging the alloy in a boat you build yourself, lives in colder lower salinity water only a few months a year, has oversized bolts in a high count as opposed to a 4 bolts arrangement. Grey seal has many small 1/2" bolts in 2 rows. And if you pull them and check them each season until you can affort SBz...maybe. Seems 316 ss could work as well, but isn't cheaper thab SBz, but not ideal. So then you come back to getting correct rod at not much more money and not look at it ever again. 40 years anyway.
In the long run your better off getting the SilBz rod and be done with it. Also AlBz, NiAlBz are good choice. If you are looking for more sources-MSC Industrial had good prices when I bought my 1/2 SB. Fry Steel in Los Angeles is another good industrial source for exotic bar stock. I got Monel rod from them at very good price relative to others. HamiltonMarine was decent $'s a few years ago.
But I'm curious your using 5/8" instead of 1/2" as the grey seal plans show. Pretty good price jump between the two sizes, so if you can get back to 1/2" the cost is better by a good bit, and 1/2" is plenty big in Ougthreds high count scheme.

[LRFBOSUN]

John Cleek: Where the H did you get that formula for Tobin Bronze?? Anaconda Industries publication B-34 gives two slightly different compositions for the stuff, both having about 40% zinc , with slightly different amounts of tin, less than 1% in either case. They are referred to as Copper Alloys #C4610 and C4700. I know LFH liked the stuff; he liked "manganese" bronze as well. Manganese bronzes are really brasses with a few percent aluminum as the principal alloying element to increase the strength. It's OK for more massive castings under(salt)water such as rudder gudgeons. There are several "manganese" bronzes. One, C67500, is 58% copper, 39% zinc, and 1% tin. The casting alloys of manganese bronze can be found in American Smelting and Refining Company (ASARCO) publication GUIDE TO COPPER CASTING ALLOYS. Their other name for these alloys is less deceptive; it's HIGH STRENGTH YELLOW BRASS. They are alloys # C86500 with 39% zinc, 1% iron and 1% aluminum and NO manganese, C86200 with 26% zinc , 3% iron, 4% aluminum and 3% manganese, and C86300 with 25% zinc, 3% iron,6% aluminum, and 3% manganese. Aluminum is the principal stregthening element. The more aluminum the stonger and less ductile. I had a lot of boat fittings cast for me years ago by Norman Leach at Jefferson Bronze in Salem Mass. He was the expert foundryman recommended to me by LFH. The exact alloy he used, and preferred by LFH, was the low strength one, C86500. The other two, medium- and high-strength, are harder to cast, have more shrinkage and, being much harder, are more likely to have casting defects as well as being more subject to breakage under impact. These days a good casting alloy is the everdur/silicon-bronze C87300 with 95% copper, 4% silicon, and 1% manganese. One of its great advantages is that it can be repeatedly remelted without any alteration in its composition since none of its constituents are subject to differential oxidation or volatilization at foundry temperatures. This lets you re-use failures, cut-ofs and machining scrap, an important consideration with ingot prices being about $10 per pound. The stuff is not easy to machine; the manganese bronzes have a better machinability index.

[kc8pql]

I love this forum. Guaranteed 180 deg. answers to every question.

[BarnacleGrim]

Why no manganese in manganese bronze?

[johnw]

John Cleek: Where the H did you get that formula for Tobin Bronze?? Anaconda Industries publication B-34 gives two slightly different compositions for the stuff, both having about 40% zinc , with slightly different amounts of tin, less than 1% in either case. They are referred to as Copper Alloys #C4610 and C4700. I know LFH liked the stuff; he liked "manganese" bronze as well. Manganese bronzes are really brasses with a few percent aluminum as the principal alloying element to increase the strength. It's OK for more massive castings under(salt)water such as rudder gudgeons. There are several "manganese" bronzes. One, C67500, is 58% copper, 39% zinc, and 1% tin. The casting alloys of manganese bronze can be found in American Smelting and Refining Company (ASARCO) publication GUIDE TO COPPER CASTING ALLOYS. Their other name for these alloys is less deceptive; it's HIGH STRENGTH YELLOW BRASS. They are alloys # C86500 with 39% zinc, 1% iron and 1% aluminum and NO manganese, C86200 with 26% zinc , 3% iron, 4% aluminum and 3% manganese, and C86300 with 25% zinc, 3% iron,6% aluminum, and 3% manganese. Aluminum is the principal stregthening element. The more aluminum the stonger and less ductile. I had a lot of boat fittings cast for me years ago by Norman Leach at Jefferson Bronze in Salem Mass. He was the expert foundryman recommended to me by LFH. The exact alloy he used, and preferred by LFH, was the low strength one, C86500. The other two, medium- and high-strength, are harder to cast, have more shrinkage and, being much harder, are more likely to have casting defects as well as being more subject to breakage under impact. These days a good casting alloy is the everdur/silicon-bronze C87300 with 95% copper, 4% silicon, and 1% manganese. One of its great advantages is that it can be repeatedly remelted without any alteration in its composition since none of its constituents are subject to differential oxidation or volatilization at foundry temperatures. This lets you re-use failures, cut-ofs and machining scrap, an important consideration with ingot prices being about $10 per pound. The stuff is not easy to machine; the manganese bronzes have a better machinability index.

That matches up with what LHF said about the composition of Tobin bronze. Where did the other formula come from?

[Alerion Sailor]

Does anyone know what type of bronze Herreshoff used for their pulley's back 1912ish.
Rufus

[donald branscom]

That matches up with what LHF said about the composition of Tobin bronze. Where did the other formula come from?

I really like it when people get their facts straight.

Many metals are given names by companies that are fluff.
They are not going to tell you the composition if it is propietary.

Anyway it is like WHITE PAINT. They can call it POMPANO BEACH WHITE if they want to.

[David G]

I love this forum. Guaranteed 180 deg. answers to every question.

Yup... and that's the best you can hope for. Often it 170, 223, 49, 112, 343, and 11 degrees.

[Jay Greer]

Herreshoff also liked Monel and called it the "Queen of Metals". His endorsement was just substantiated when the monel keel bolts were pulled from the one hundred year old 71' Lawley ketch "Shawnee" that is, currently, under restoration. The forty l l/2"x3' bolts are as good as the day they were installed in 1911! There is no corrosion or galvanic degradation showing on any of them!
Jay

[Bob Cleek]

That matches up with what LHF said about the composition of Tobin bronze. Where did the other formula come from?

Being as I looked it up over a year and a half ago, I'd have to answer, "Damned if I know." I do know that I didn't make those formulas up because I sure don't carry them around in my head. I looked it up somewhere. Further research indicates they were certainly wrong. Tobin Bronze is a trade name and the exact formula is proprietary in any event. It is not a "true bronze," but is actually classified with the brasses, so Tobin bronze is indeed a "naval brass."

This comes from "Marine Engineering, Volume 26," out of an article on marine metals by Horace Holden Thayer:

http://books.google.com/books?id=-1g...ze&output=text

__________________________________________________ _________
Tobin Bronze

(23) Tobin bronze is a proprietary composition whose exact mixture is not published by its manufacturers. Analyses of the metal as found in engineering handbooks show it to be very similar in composition to (maganese bronze) though with less iron and no manganese. It meets the requirements of the Navy specifications for rolled naval brass (Copper 59 percent to 63 percent, zinc 40.5 percent to 35.5 percent, tin .5 percent to 1.5 percent, with maximum allowable impurities of .2 percent lead and .06 percent iron: Navy composition X-r for rolled naval brass.) which allow only .06 percent iron, and probably contains a fraction of a percent of other metals used by the makers to bring about the desired results.

This composition has great tensile and torsional strength and great resistance to the corrosive action of sea water. Results from its use have been consistently successful, and it has been found to be a most desirable alloy for—

Plates and shapes of bronze yachts and other vessels where in contact with salt water.
Rudders and rudder stocks.
Condenser tube sheets.
Condenser tube supporting plates.
Pump valves.
Pump rods and valve stems.
Propeller shafts of small vessels in salt water service.
Wooden ship sheathing.
Hinge pins.
Bolts, screws, nails and other fastenings in contact with salt water.
Deck and spar fittings of yachts.

__________________________________________________ ______________

As can be seen, Tobin bronze certainly isn't made of 82% copper as stated in my earlier post. Bosun's formula looks a lot closer to what the technical text states.

BTW, the Google Books text of "Marine Engineering" is a PIA to read, but it does have one of the better treatments of all the marine brasses and bronzes I've seen.

[johnw]

Thanks, Bob. There's a lot of information out there, and it's hard to sort.

[MN Dave]

Yes, they are currently the same alloy, but in 1875 Tobin Bronze was a little different. It had more tin and some lead. It is hard to say over the years what exact composition any particular batch of Tobin Bronze had, but regardless of the minor variations, the mechanical properties and corrosion resistance were not much different. A list of old copper alloy names is here: http://www.oldcopper.org/glossary.htm

The best information I can find is that the alloy currently sold as Tobin Bronze is the same as naval brass, AKA uninhibited naval brass, CDA 464 (UNS C46400). The nominal composition is 60% Cu, 39% Zn and 1% Sn. One reference said that Tobin was C46400 processed for fine grain size, which should give it more strength.

Saltwater leaches zinc from brass unless a small amount of antimony or arsenic is added. The Handbook of Oceanographic Engineering Materials gives low rates of general corrosion, but a 57% loss of strength after 16 years in seawater due to dezincification. Inhibited admiralty (CDA 443, 444 & 445) is 71% Cu, 28% Zn and 1% Sn with 0.6% As, Sb or P added to inhibit dezincification. It looks like a spongy layer of copper over a brass core when it breaks.

The Mechanical Engineer's Pocket Book, 1898 says that the original proprietary Tobin Bronze had more tin and some lead. Lead makes it easier to machine.
http://books.google.com/books?id=Ei8...sition&f=false

Somewhere in this thread, someone said that 302 stainless contains lead to make it machine more easily. Free machining stainless is 303, and it contains sulfur, not lead. 302 is very similar to 304, and both can pit severely, but not as badly as 303. 316 is better, but not that much. The The Handbook of Oceanographic Engineering Materials recommends that if submerged, 302 and 304 not be used more than 2 months, and 6 months for 316 without cathodic protection. As for 303, they start out with 'warning, not suitable for seawater service'.

Brass and Bronze generally refer to copper alloys containing zinc and tin, respectively. This rule was made to be stretched and broken. Bronze is also used for alloys containing anything other than zinc.

[johnw]

That's interesting, Dave. Herreshoff started using it for hull plating around 1893, I wonder which version that was.

[Nicholas Carey]

NAVEDTRA 14250 (Non-resident Training Course: Steelworker, Volume 1), the 1996 Navy Steelworker's course, chapter 1, describes Tobin Bronze as being the same as naval brass:

Naval rolled brass (Tobin bronze) contains about 60% copper, 39% zinc, and 0.75% tin. This brass is highly corrosion-resistant and is practically impurity free.

http://www.globalsecurity.org/milita.../14250_ch1.pdf

According to the Copper Development Association (http://www.copper.org/) that administers the copper/brass/bronze piece of the UNS alloy numbering system, Naval Brass is alloy C46500 and Admiralty Brass is C44300. The spec for their composition is as follows:

• C44300 (Admiralty Brass)
  
  • Nominal: 71.0% Cu, 0.04% As, 1.0% Sn, 28.0% Zn
  • Allowed: 70.0-73.0% Cu, 0.02-0.06% As, 0.0-0.06% Fe , 0.0-0.07% Pb, 0.8-1.2% Sn, Remainder Zn
• C46500 (Naval Brass)
  
  • Nominal: 60.0% Cu, 0.04% As, 0.7% Sn, 39.2% Zn
  • Allowed: 59.0-62.0% Cu, 0.02-0.06% As, 0.0-0.10% Fe, 0.0-0.20% Pb , 0.50-1.0% Sn, Remainder Zn

[johnw]

NAVEDTRA 14250 (Non-resident Training Course: Steelworker, Volume 1), the 1996 Navy Steelworker's course, chapter 1, describes Tobin Bronze as being the same as naval brass:

Naval rolled brass (Tobin bronze) contains about 60% copper, 39% zinc, and 0.75% tin. This brass is highly corrosion-resistant and is practically impurity free.

http://www.globalsecurity.org/milita.../14250_ch1.pdf

According to the Copper Development Association (http://www.copper.org/) that administers the copper/brass/bronze piece of the UNS alloy numbering system, Naval Brass is alloy C46500 and Admiralty Brass is C44300. The spec for their composition is as follows:

• C44300 (Admiralty Brass)
  
  • Nominal: 71.0% Cu, 0.04% As, 1.0% Sn, 28.0% Zn
  • Allowed: 70.0-73.0% Cu, 0.02-0.06% As, 0.0-0.06% Fe , 0.0-0.07% Pb, 0.8-1.2% Sn, Remainder Zn
  
  
• C46500 (Naval Brass)
  
  • Nominal: 60.0% Cu, 0.04% As, 0.7% Sn, 39.2% Zn
  • Allowed: 59.0-62.0% Cu, 0.02-0.06% As, 0.0-0.10% Fe, 0.0-0.20% Pb , 0.50-1.0% Sn, Remainder Zn
  
  

But as Dave points out, the formula changed over time. Tobin Bronze was originally a trademark, I believe of the American Brass Co., although I think they became part of ASARCO. They probably felt free to change the formula, especially in the 19th century.

[MN Dave]

While we're at it, I think you could say that C48200 (naval brass, medium leaded) is pretty close to the old Tobin Bronze, as is C85700 for sand castings.

The old engineers pocket book mentioned above has an analysis of Tobin Bronze ingot and rolled bar. In that case, half of the tin was lost in the casting and rolling process. I think that a lot of the variation you see in the composition over the years might not have been intentional.

In the information overload department, the Copper Development Assoc. website is not as easy to navigate as it used to be. My hard copy of the Copper Development Association Standards Handbook (1985) lists C44300 (admiralty, arsenical), C44400 (admiralty, antimonial) and C44500 (admiralty, phosphorized). These alloys are so close that they group them and give one set of mechanical and physical properties for the group.

The next group on the list is "C46400, C46500, C46600 and C46700 (naval brass, uninhibited)" on the following page. Only C464 is uninhibited. In the footnote under the composition, they mention that next 3 have the same inhibitors as Admiralty in the same order.

www.michel-christen.com/2T-H.pdf attempts to shed some dark on the corrosion issues and standards.

Dave

[ssor]

I have found that these people are rather comprehensive in theirdiscription of themany copper alloys.
http://www.anchorbronze.com/

[Canoeyawl]

I don't know why anyone would want that much zinc (appears to be just brass) when you can use Everdur.

High Silicon Bronze A , CDA 655 Everdur

[johnw]

I don't know why anyone would want that much zinc (appears to be just brass) when you can use Everdur.

High Silicon Bronze A , CDA 655 Everdur

Cost?

[Canoeyawl]

Well, You get what you pay for.

[redbopeep]

This is an interesting discussion. Here's our experience so far: We had a variety of brasses and bronzes on our schooner--all originally installed 1931. Some were in great shape 80 years later and some we replaced some as follows:

Keel bolts originally 1931 Tobin Bronze, replaced with Silicone Bronze;
Keel drifts originally 1931 galvanized steel, replaced with spiral cut Silicone Bronze;
Chain plates originally 1931 Tobin Bronze; they were in good shape except where they went through the deck and around the hull bolts (galvanized steel bolts) where they had pinked and eaten away; replaced with Tobin Bronze (aka Naval Brass) except for forestay chain plates which we replaced with Silicon Bronze because we happened to have the SB stock hanging around and running back cast manganese bronze ones which were installed in 1939 and are also in great shape still; Note the Silicon Bronze turns bright green with a dusty oxide that you can rub off but the Tobin Bronze/Naval Brass turns to a brown color which is finer and doesn't rub off the same way.
Bobstay Iron was Manganese Bronze 1931 and had some pink spots on it so we re-cast in Manganese Bronze;
Rudder gudgeon was cast of what looks like some sort of Brass or bronze, but was worn and galled; we recast in Manganese Bronze;
Some Mast rings and various deck hardware cast for the boat 1931 were originally Manganese Bronze (which is a brass), all but one were in perfect condition, that one damaged was cast in Manganese Bronze; Interesting things about Manganese Bronze--it oxides to a whitish tan color, not green at all and it is very slightly magnetic;
The (1939 with re-rig) main mast head fitting (tree) is cast Silicon Bronze and in great shape;
Other mast hardware and deck hardware were silicon bronze known to be installed in 1968 (Merriman) and was pink and not in great shape;
Rudder stock was originally Tobin Bronze, cast and machined 1931. Had some pink areas so we replaced with new Tobin Bronze/Naval Brass hot worked and welded;
Cheek plates adjacent the gudgeon were in fine shape and re-used. Don't know the material but assume from the looks of them that they were Manganese Bronze; Same for a "clam" bearing on the rudder which bolts thru the rudder itself.
Rudder shaft was originally an Atlas Brass plumbing pipe 1931, still in good shape so we re-used;
Shaft log was some sort of brass thin walled tubing threaded into the stuffing box (inside) and stern bearing (outside). Ruined when we removed it. We replaced with a red brass thin walled tubing, threaded the same. The original 1931 Silicon Bronze stern bearing housing was pinked and we replaced in kind with a new Silcon Bronze Wilcox Crit. one.

With all the brasses and bronzes on the back end of the boat, we have been very careful to keep track of voltage and track it with use of a Silver-Silver Chloride half cel. A zinc anode is too aggressive (too much voltage) so we actually have made mild steel anodes which are attached to the cheek plates either side of the gudgeon and seem to be doing the job nicely. We do worry about beefy (2-1/2") Tobin Bronze/Naval Brass rudder stock having its zinc eaten away if we don't keep the anodes in proper shape. The two small 3"x1"x3/8"thick mild steel anodes are replaced every 6 months; the prop (manganese bronze) has a G-size shaft nut zinc on it which we replace every 8 months. All is working so far.

Naval brass/Tobin bronze makes me a little nervous but we decided to use it as it was spec'd by the Naval Architect (Crocker) and we saw that it generally lasted.

[seo]

I pretty clear recollect that LF Herreshof mentioned Tobin Bronze as being good stuff because in the process of rolling it out into sheet metal it became quite uniform in its composition, and so was very predictable. Maybe in "Commonsense of Yacht Design?)
This description is quite similar to what's quoted in post #42 above:
"
NAVEDTRA 14250 (Non-resident Training Course: Steelworker, Volume 1), the 1996 Navy Steelworker's course, chapter 1, describes Tobin Bronze as being the same as naval brass:

Naval rolled brass (Tobin bronze) contains about 60% copper, 39% zinc, and 0.75% tin. This brass is highly corrosion-resistant and is practically impurity free."

A very desirable quality in any construction material is consistency. Isn't that the central problem with stainless steel...some pieces hold up beautifully for a long time, others from the same lot, in the same application, go all to Hell in a couple years. And you can't tell which piece will do what.