Navel brass or silicon bronze chain plates?

[Jeff PT403]

I have a Triton and would like to move the chain plates to the outside.
A local suppier has Navel Brass the Silicon Bronze would be harder to
get and would be 1/4" x 2" I was thinking 1/4" x 1 1/4" Navel Brass.

Thanks for your help.

[Figment]

I know it's a no-no, but I can't recall the specifics of why. Probably something to do with the work-hardening of the brass leading to it becoming brittle. The metallurgical details of it are escaping me at the moment.

Try asking the folks over at Brion Toss's forum.

Who is the supplier? Are they rigging people, or just metals people?

[Rachel]

I'm with Figment. I know you don't want to use naval brass, but can't remember the metallurgy behind it. You want bronze or stainless steel (I vote for the bronze).

Sizing goes by wire size, and here is a chart from Skene's Elements of Yacht Design, 8th edition, edited by Francis S. Kinney, for guidance:

I don't believe there's any harm in the chainplates being larger than necessary (unlike, for example, the rigging wire, which you want to keep close to design specs).

Rachel

PS: I'm not sure if it's okay to post this excerpt from Skene's here? If not I could come back and remove it and just type in the sizing information for the Triton's wire size (I wasn't sure what size it was or I would have).

[Paulus]

Brass, including Naval Brass, contains a lot of Zinc (as much as 40% by weight), as opposed to Tin being used to create Bronze alloys.

Over time, as with sacrificial zincs on propeller shafts, etc., the zinc, when exposed to galvanic action, can leave the brass and get deposited on metals of higher "nobility", i.e. located higher on the scale of electropotential series, including copper and stainless steel... The brass can litterally become porous as the zinc separates from the alloy, leaving mostly copper, without much remaining structural strength.

Tin (as used in Bronze), lead and Copper are very close in nobility and when used together in alloys, this is much less of an issue.

But I am sure you already knew that.

[Jeff PT403]

Ok I'll go with the silicon bronze.

Thank you all.

Jeff