Stainless steel nuts on Galvanised mild steel.

winsbury said:
I read recently not to over tighten galvanised shackes as this can damage the thin layer of zinc leading to premature corrosion. Surely stainless nuts are much harder than the zinc galvanising and very likely to damage this thin protective coating when pinched up hard.
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The advice you read was not great. The beauty of galvanising is that it is an anodic coating, not paint. The zinc continues to protect even if adjacent steel is totally exposed. A further point is that hot dip galvanising leads to a range of Fe-Zn compounds, some of which are not visible. Hence a chain, for example, that looks black with no bright zinc, remains corrosion free. So your shackle may have no visible zinc but will still not rust.
 
vyv_cox said:
Lots of 'pseudo-metallurgy in this thread!

Keel bolts may well get damp, but their material is the same as was originally specified. The joint between the stainless and the galvanised steel should remain pretty well dry and even if it did get wet the corrosion rate would be low. The bolts and keel are the anode but they are vastly bigger than the nuts.

Once again, crevice corrosion is a form of corrosion and has nothing to do with oxygen being excluded from the environment. The crevice creates the lower oxygen content. See my website under 'metallurgy'.

Grease? There are specialist bedding sealants for keels, although Sikaflex 291 seems just as good. Nuts and washers are normally flowcoated in the bilge.

Galvanised bolts are widely used in a variety of wet conditions. Why should the zinc 'break down' in the threads? It's only a few microns thick anyway. I saw a programme about repairing old piers recently. All the bolting was galvanised.

What is the mechanism for zinc 'donating its electrons' to the stainless steel? A diffusion mechanism is known, not at all the same thing, but that is a high temperature mechanism.

Galling occurs between stainless nuts on stainless bolts. One way to avoid it would be to have one component in carbon steel, the other in stainless.

A method that used to be used on tankers to prevent nuts from corroding onto bolts was to put brass nuts on carbon steel bolts. Effective and far cheaper.
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I thought oxidation was a loss of electrons and the more Noble metal "donated" it's electrons more willingly - thereby protecting the less Noble one for as long as it had electrons to give?
 
BlueTwo said:
I get asked this a lot. Marieholm, Westerly, Nicholson, and many many others do not charge for access to their web pages. I have gained quite a lot of information about Moody yachts due to my experience commissioning the one I presently have. With other makes of yacht I have contributed tips and hints and cruising experience. With Moody I am not allowed to contribute information unless I pay them £25.

Quite frankly they can get stuffed.
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Worse than that, I was once enjoying a liesurely G&T of a Saturday night at home when I got a phone call from some pompous old fart at the Moody site haraguing me for inadvertently beaking one of their many rules in a post I had made - something trivial like using my initials instead of my name in a post. I was so surprised that I didnt even respond in kind. So I think your issue and mine is simply down to the type of people involved.
 
Bosun Higgs said:
Worse than that, I was once enjoying a liesurely G&T of a Saturday night at home when I got a phone call from some pompous old fart at the Moody site haraguing me for inadvertently beaking one of their many rules in a post I had made - something trivial like using my initials instead of my name in a post. I was so surprised that I didnt even respond in kind. So I think your issue and mine is simply down to the type of people involved.
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When I bought the Moody I was given the access code to the web pages. I had a quick look round before the access code was cancelled. It had all the hallmarks of an American money making scam. Technical Articles that were written by the members were locked away in a seperate web page. An on-line magazine was all advertisements with one or two (at the most) articles also written by members.

I have no doubt that there are other one design classes that charge a membership fee for the club but those I know like the Hallberg Rassy web pages are a mine of information in the free spirit of the internet.

I only make an issue of it because nearly every time I meet a Moody owner I am asked to join the club for £25. What gives with that crowd?

Edit: Just read my post and it sounds like I am against paying for club organisation of meetings, dinners and club rooms. I am not. I belong to the Swedish Folkboat Club and enjoy meeting folk on their premises with events, bar lounge, showers, reading room etc. BUT our web pages full of friendly hints and technical articles and go-faster mods are wide open to anyone who cares to browse and learn about the class.
 
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I was a member of the Sadler and Starlight members association but now that we sail in Greece there seemed to be little point. The newsletter/magazine was quite good but I was not learning a lot from it. Don't know current membership cost but probably similar to Moody.

However, the important point is that the forum is free for anyone. Every question that has ever been raised about these boats has been answered by experienced people and can be seen by all and sundry.

A few months ago my attention was drawn to a question on the Moody site, requesting me to give my professional opinion for the benefit of the owners. I was refused permission to post!
 
I contribute occasionally to PBO Forums and am an avid reader of them.I own a Moody 31 and am a member of the Moody Association.In my opinion the £20 p/a that I pay is one of the best investments that I make.There is a wealth of information available and I have received a great deal of help from other members.There will always be one or two members who are over protective as there are in all organisations.It was decided by the members that the technical information would be restricted to members as the website was inundated by people wanting information for free.Just my opinion of course.
 
are you sure the galvanised studding is not just zinc plated? all the studding I have seen in greece is plated. But galvanised nuts are easily available in UK and I know mild steel (black) are easily available in greece. I cant understand why you cant find them?
 
ditchcrawler said:
I contribute occasionally to PBO Forums and am an avid reader of them.I own a Moody 31 and am a member of the Moody Association.In my opinion the £20 p/a that I pay is one of the best investments that I make.There is a wealth of information available and I have received a great deal of help from other members.There will always be one or two members who are over protective as there are in all organisations.It was decided by the members that the technical information would be restricted to members as the website was inundated by people wanting information for free.Just my opinion of course.
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So why not publish the password on here so we can look at what is so secret the "protective" members wish to lock away.
 
vyv_cox said:
I was a member of the Sadler and Starlight members association but now that we sail in Greece there seemed to be little point. The newsletter/magazine was quite good but I was not learning a lot from it. Don't know current membership cost but probably similar to Moody.

However, the important point is that the forum is free for anyone. Every question that has ever been raised about these boats has been answered by experienced people and can be seen by all and sundry.

A few months ago my attention was drawn to a question on the Moody site, requesting me to give my professional opinion for the benefit of the owners. I was refused permission to post!
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That is the reason I will not join this "club". The membership fee is levied every year so, at a later date, you will be locked out of your own posts if you don't pay up every year. How's that for a copyright grab.
 
ccscott49 said:
are you sure the galvanised studding is not just zinc plated? all the studding I have seen in greece is plated. But galvanised nuts are easily available in UK and I know mild steel (black) are easily available in greece. I cant understand why you cant find them?
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Thank you for the info that they are indeed available in Greece. It's just that I havn't stumbled across them yet. I will keep looking and maybe source them in Levkas, for instance. Yes, I agree, the studding I bought in Greece could be zinc plated. I wouldn't know the difference, or if it matters.
 
Does the pitch of M24 threaded rod and nuts vary ? Are there coarse (3mm) versions and fine (1.5mm) ?
 
BurnitBlue said:
That is the reason I will not join this "club". The membership fee is levied every year so, at a later date, you will be locked out of your own posts if you don't pay up every year. How's that for a copyright grab.
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Love it, some site owners think they are onto a good thing and milk it for all they can get, what I don't understand is all the fools that pay!
 
parsifal said:
And on MG-B exhaust manifolds!
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years ago most cars used brass nuts to stop them rusting on. I had a lada for a while when I came to change the front pipe that had brass nuts . I had been looking forward to the rusted nuts it was such a letdown.

Not sure about this discussion and I dont know where this stands in it but every discussion i have seen on gavanised chain says dont use stainless shackles as the chain the chain links will degrade even a meter away from the shackle on that basis, not exactly scientifikk, I would look for the proper nuts , if only to sleep through the night !

edit night watch 3 months in I wonderif those nuts are ok ?
 
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