keel bolts

PabloPicasso

PabloPicasso

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Is it better to use stainless steel keel bolts in a cast iron keel, or would this increase the likelyhood of galvanic or crevice corrosion?

What is the life expectancy of steel (not stainless) bolts in a cast iron keel?
 
316 Stainless works very well.I pulled one of mine and it was absolutely like new.It's 30years old .Curiously there was oil at the bottom of the hole.Maybe that was a Westerly practice.
If you use plenty of sealant(not silicone) to prevent water entering the threads there won't be crevice corrosion.
 
316 stainless is the most common material these days. On modern boats it is rare to get any water near them.
 
Tranona said:
316 stainless is the most common material these days. On modern boats it is rare to get any water near them.
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Stewart
Am puzzled, on my two Benes they were/are ordinary steel, on Richards Moody they were ordinary steel. Does Bav do something different?
Stu
 
As far as I know they are 316 - look like it from the top. Don't think there is anything wrong strengthwise with mild stell - just as Richard found out the hard way, Moodys leak and the nuts, plates etc end up a mass of rust whereas the bolt itself is fine.

Against all the advice I bolted my iron keel back on to my Eventide with 316 bolts made of bar threaded at either end, having had 2 sets of mild steel corrode in the classic way. Made sure I filled the holes with sealant as far as possible. Been there since 1992 and no signs of corrosion - but have not been brave enough to take them out for inspection yet!
 
Pete7 said:
:( I polish the dry bilges of my Moody with Mr Sheen to keep the dust down and make her smell nice.

Pete
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I am sure there are dry Moodys, but every one that I looked at when I was buying (mostly 37s 376s and older 33s and 36s) had water in the bilges from leaks from sources such as the anchor locker, chain plates or windows and the nuts were rusty. On one (rather neglected) boat there was so much damp that the entire main bulkhead needed stripping and re-finishing.
 
Gaffers said:
What is the opinion on A4 Stainless for marine applications?
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It's the alloy of choice. AISI 316. Used for just about everything in the boating world. Many will tell you it shouldn't be used underwater, forgetting that perhaps 95% of drive shafts are made from it. It isn't good where there is a crevice of any sort, such as threads, unsealed fittings, etc but otherwise fine.
 
So keepeing water out is easy and therefore no corrosion. I'm not convinced about that!.

What about the galvanic action between cats a nd stainless?? Is this a concern, if not why not?
 
PabloPicasso said:
So keepeing water out is easy and therefore no corrosion. I'm not convinced about that!.

What about the galvanic action between cats a nd stainless?? Is this a concern, if not why not?
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It would be helpful if you explained why you are interested and what your concerns are. Both mild steel and stainless are used successfully for keel bolts. In modern GRP boats where they are tapped into the casting, problems with keel bolts are very rare.

It is different if you are talking about external ballast keels bolted to wooden keels in flexible wooden structures - ie "traditional" construction. That is a completely different situation because of the mix of materials and difficulty of keeping water away from the joint.
 
PabloPicasso said:
So keepeing water out is easy and therefore no corrosion. I'm not convinced about that!.

What about the galvanic action between cats a nd stainless?? Is this a concern, if not why not?
Click to expand...

As far as I am aware the stainless steel bolts have held my cast iron keel undisturbed for 25 years. No water leaks into the boat, which pretty much assures me that none, or very little, is reaching the bolts.
 
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