Bronze chainplates silicone bronze or aluminum bronze

[Eastward ho 24]

Here's a few pics before the refletix 1/2" closed cell foam and knees fiberglassed in with 1708 mat and epoxy

[boatpoker]

Originally Posted by rbk

To make tying it all together easier try and find some lengths of copper flat bar to use as common bud bars rather than having six miles of wire running in your bilge. On the bronze either will do, aluminium, silicone or manganese are all suitable and avaialability will be your deciding factor. PTF uses manganese or silicone, classic marine uses aluminum.

Do not use manganese !
Manganese is bronze in name only. Zinc content can be as high as 35% and falls squarely in the "brass" category. Not suitable at all for chain plates.

[coastalexplorer]

Polished Aluminum Bronze has the same sheen as 9 Carat gold.

[rbk]

Originally Posted by boatpoker

Do not use manganese !
Manganese is bronze in name only. Zinc content can be as high as 35% and falls squarely in the "brass" category. Not suitable at all for chain plates.

Not sure where this can from but very inaccurate and is highly dependant on the quality of the alloy. Avoid cheap alloys period. Most manganese alloys like C66800 will contain manganese, iron, aluminium, lead with no zinc. Marine grade or high stress bronze alloy’s will/should be mixed to their application. I am fairly certain that all PTF’s marine hardware is maganese bronze, might be silicone. A good manganese alloy is highly suitable for high stress and extremely corrosion resistant and is regularly used in marine, aerospace and oil and gas industry.

[Eastward ho 24]

And ideas what what it'll cost to get some made? I've got 7/16 turnbuckles?

[boatpoker]

Originally Posted by rbk

Not sure where this can from but very inaccurate and is highly dependant on the quality of the alloy. Avoid cheap alloys period. Most manganese alloys like C66800 will contain manganese, iron, aluminium, lead with no zinc. Marine grade or high stress bronze alloy’s will/should be mixed to their application. I am fairly certain that all PTF’s marine hardware is maganese bronze, might be silicone. A good manganese alloy is highly suitable for high stress and extremely corrosion resistant and is regularly used in marine, aerospace and oil and gas industry.

I suggest you do some more research. Maganese bronze by definition contains high levels of zinc. I am A Certified Marine Corrosion Analyst.

You may want to consider what Brian Toss (one of the most respected riggers in the world) has to say about it.

[Toaster]

Originally Posted by rbk

Not sure where this can from but very inaccurate and is highly dependant on the quality of the alloy. Avoid cheap alloys period. Most manganese alloys like C66800 will contain manganese, iron, aluminium, lead with no zinc. Marine grade or high stress bronze alloy’s will/should be mixed to their application. I am fairly certain that all PTF’s marine hardware is maganese bronze, might be silicone. A good manganese alloy is highly suitable for high stress and extremely corrosion resistant and is regularly used in marine, aerospace and oil and gas industry.

PTF has made several parts for me and used silicon bronze and nickel aluminum bronze. Can't recommend PTF highly enough, they do superb work.

Pete at PTF actually knew what a white metal bearing was, had the materials on hand, manufactured it, and fit it perfectly to my prop shaft. And it took one day from the time I handed him the old white metal bearing and the shaft, to when he handed me the new one.

[rbk]

Manganese bronze alloys C66800, C67300, C67400 and proprietary SMM (used for props and prop shafts) contain little to no zinc so you’re generalizing a broad spectrum here. It’s like saying all stainless steel is the same and I know you know it’s not.

[boatpoker]

Lots of free dictionaries online, Google "Manganese Bronze Definition".

[Jim Cate]

Originally Posted by rbk

Manganese bronze alloys C66800, C67300, C67400 and proprietary SMM (used for props and prop shafts) contain little to no zinc so you’re generalizing a broad spectrum here. It’s like saying all stainless steel is the same and I know you know it’s not.

I dunno,RBK... look at the linked table of composition for C66800: it seems that it contains nearly 40% Zn, not "little to no Zn"



https://www.azom.com/article.aspx?ArticleID=8989

Jim

[mitiempo]

Originally Posted by Jim Cate

I dunno,RBK... look at the linked table of composition for C66800: it seems that it contains nearly 40% Zn, not "little to no Zn"



https://www.azom.com/article.aspx?ArticleID=8989

Jim

I agree. About 30% zinc in the best case scenario as far as I can tell.

https://certifications.thomasnet.com...ganese-bronze/

Manganese bronze is the most common alloy used for propellers. It's zinc content is the reason why a shaft zinc is so important - without it the zinc in the prop becomes the anode.

[kimtrang]

Daveys in the U.K. make part manganese bronze chainplates. I just bought 4x 12" and 2 x 14" to replace my internal plates. Paid $us500 or so from a local store.

Bottom of page 29
http://davey.co.uk/pdf/rigging.pdf

https://shop.classic-boat-supplies.c...tes-undrilled/

[rbk]

Missed that one allow, still pretty low on the brass scale. I agree with boatpoker in the corrosion department for manganese bronze below the waterline. When you start looking at different alloys and their properties each has their own benefits and drawbacks. For example aluminium bronze can contain anywhere from 80-98% copper and 15-2% aluminium. Would you trust a chain plate made mostly from copper? It would be very corosion resistant but would lack the structural strength required for a chain plate, same goes for silicone bronze; but is ideal for thru hulls. Aluminium is also susceptible to corrosion and would never be considered for a thru hulls but are regularly used for spars, hulls and anodes, go figure. Personally I went with an aluminium nickel bronze alloy. I was also considering an aluminium manganese bronze alloy but it came down to availability. Zinc is added to copper for strength, manganese to aluminium for corrosion resistance, nickle is also good for corosion but too much and the alloy becomes brittle, Silicone helps with friction applications but keeps its soft, same with lead and list goes on. Just like boats everything is a compromise.

[Cheechako]

IIRC BRonze fittings from Spartn/Cape Dory are silicone bronze right.?

[Jim Cate]

Ahh, come on guys... it's silicon bronze, not silicone!

Jim