A Good Pictorial On SS Corrosion

this is worthy of a gander…

http://www.dixielandmarine.com/yachts/DLrigprob.html

Interesting! Thanks, Ben.

Did Douglas tell you his ideas, which I have followed, of adding a bronze bolt and nut to the bobstay tang and bronze washers to the boomkin clevis pins?

Cheers

Bil

Bill,

Yes Douglas has shared that idea, I like it alot. The 3 plates I have to replace due to cracks are being replaced with Bronze. Took me a while to decide, but I think it’s the way to go. One decision made… Next!

See You in Australia one of these days…

Hi Bil, I am not sure that I told Ben, about using bronze as a sacraficial (sp-?) metal, like a zink is for our propellers, but that is what I think you are refering to.

What I did give as a “heads up”, to Ben, was about iron contamination on his ss wire, after he used iron tools on his 1 x 19 ss wire, during splicing operations.

This link below is quite good information on cleaning your ss after working it, and before installation.

http://www.outokumpu.com/applications/upload/pubs_113142858.pdf

You need this whole web address , to take you to the Pickling Handbook, but the last part of the address, may get deleted,when I submit this post, so I will add it here too :
…com/applications/upload/pubs_113142858.pdf

Douglas

“The 3 plates I have to replace due to cracks are being replaced with Bronze.”

Ben,

I also wanted bronze but couldn,t get it in Thailand so have replaced all my stainless with stainless for now including the bobstay tang which although technically dubious (following an extensive indoctrination in the pros & cons of stainless by Douglas when we were together in Malaysia a few years back) has at least weathered several tropical storms in Xiphias lifetime so far.

Regarding the chainplate holes you mention on your webpage, I decided to go with round holes (less likely for a crack to spread)rather than square. I sent the stainless carriage bolts to the machine shop (same people who made the chainplates) to have the squares rounded off and slots put in the tops. See attached photos.

Regards,

Mark Fuller

BCC 034 Xiphias

Mark,

She’s looking very nice from the little I can see in those photos!!

SO if I understand you correctly, you basically turned your carriage bolts into large slotted bolts?

http://www.mcmaster.com/param/images/machine/bindingheadslotted.gif

Douglas: Hi!

Yes, I was specifically referring to the lesson I learned from you about using the zince in a bronze fixing as a sacrificial anode to protect the bobstay tang.

And I was reminded of it by the photo on the dixielandmarine.com page to which Ben referred: it’s a photo of the bobstay bowsprit tang on a Vagabond 42. The photo shows the ss of the submerged part of the bobstay stem fitting massively pitted by corrosion.

For those who haven’t heard, Douglas suggests the simple fix of adding a cheap bronze bolt, washer, and nut to the bobstay tang. And bronze washers to the clevis pins of the boomkin transom fittings. The zinc in the cheap bronze/brass acts as a sacrificial anode, protecting the ss if protection is needed. If the bolt starts to dezincify, the bolt will turn a pinkish color.

On Zygote, that bolt has not dezincified. Suggesting that the protection has not been needed. But better safe than sorry.

Cheers

Bil

Ben,

Exactly.

Regards,

Mark

Hi Bil and Douglas,
Did you mean to say BRASS or BRONZE? Most Bronze bolts/nuts are fabricated from Al.Brz (88-96.1% Cu, 2.3-10.5% Al, trace Sn, Trace Fe) or Si.Brz. (97.6% Cu, 1.4% Sn, 1.0% Si). Note that there should NOT be any zinc in these. I say should as there are a lot of inferior imported bolts on the market that do have some zinc in them. If you do want to use the zinc content for protection, I would suggest to look at brass rather than bronze.
Beautiful pictures Mark.

Regards,
John

Mark

Nice job of mounting the Cape Horn Windvane Steering System. I noticed the unit on your boat is mounted outside the bumpkin. Is your Cape Horn desiged to be mounted aft of the boomkin or did you modifiy the mounting?

Rod

mark, didnt see the pics till now – gorgeous!