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Old 20-07-2007, 18:23   #1
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Bob-stay material

I need to replace the 10ft. Bob-stay from my vessel. Currently it is 7/16" wire with swages. Unfortunately, the lower tang is 6"s under water. This is quite insane when you figure one of the swages is submurged also. The old stay is showing signs of corrosion. I want to replace the wire with chain. I'm thinking I can use 1/2" chain with a Stainless D-shackle on the tang to the chain and then chain up to the turnbuckle. I see this all the time with bow-sprits. I was wondering if its ok to use regular 1/2" galvanized chain with the stainless steel or does it have to be stainless chain also? Galvy would be a little stonger than the stainless and a whole lot cheaper!
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Old 20-07-2007, 23:03   #2
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galvanized chain is a very popular material with older style bowsprits. It's easy to inspect to tell when you have to change it. We did it on our old boat. Only caveat - have some means of tensioning it!
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Old 20-07-2007, 23:21   #3
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Don't be too quick about the change to chain, you might not be solving the problems you think.

Chain (especially stainless) is MORE susceptable to electrolyic corrosion than wire, and more importantly, chain fails without notice. Chain losses strength without easily visible changes, and then fails suddenly and completely. As wire loses strength a simple visual inspection tells you things are wrong.

It is an especially bad idea to mix galvanised and stainless parts.

Yes, you see chain used here a lot, but that doesn't mean it is the right answer!

Consider your bobstay a routine maintenance item.
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Old 20-07-2007, 23:36   #4
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Here's what I would do from a machinist's point of view.

Since part of it sits under water, I would make a Inconel toggle long enough to bring it well above the water line and then make up a SS cable for the rest of the way.

As for galv. chain, it's very EZ to keep an eye on the stuff. If a crack starts to form it will bleed and you'll know it would be failing. But having it under water 100% would not be so great. And then attaching it to SS would be another problem.

Now SS chain, I wouldn't trust any where near the salt/piss............._/)
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Old 21-07-2007, 01:57   #5
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Thanks Evan, Greatketch and Del. I was also a Machinist and tool maker for many a year, so I see your good point. I see my question has been answered regarding mixing Galvy with stainless. Not a good idea...ok, got it!
So my next idea is perhaps to use 2, 1/2" "D"shackles to bring everything out of the water and going chain from there. The 1/2" chain appears to have a breaking strength 30% higher than the present 7/16" wire. I know for a fact that the wire is over 5 years old. That is surprising considering it's been underwater the whole time. Hoping for some more ideas.
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Old 21-07-2007, 03:14   #6
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I have seen galvanised pipe used successfully, with the overall length short by a few mm's then ever so slightly tensioned with a come along until the tangs line up, the only down side is if you run into something it will bend whereas galv chain wont.
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Old 22-07-2007, 22:25   #7
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Forgive me for asking, but shouldn't the bobstay fitting be ABOVE water?
While we were cruising on our LN 35, it was very easy to accumulate things. I was always having to look around and make decisions on what to toss.

Maybe you need to "defrost" your boat?

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