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Old 02-05-2016, 10:25   #1
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What is this protective covering on my keel bolts?

Alright, some may remember that I asked what to do about the corroded keel bolts in the bilge of my van de Stadt Pionier. I've spent a bit of time digesting the suggestions (just remove the keel etc.) and got some local advice as well. Decided to start by hammering the rust off the bolts and see how bad things really are. I was quite surprised after hammering off thick pieces of what I thought was rust to find perfectly shaped hexagonal nuts under those layers I had knocked away.

I think what I knocked away was not rust at all, at least not rust belonging to the bolts and nuts, but some protective layer of (possibly) ferric material.

Attached images show, in order:

1: keel bolt and nut after knocking away the layers of "rust"

2: keel bolt and nut, and a piece of the layer that had been covering them, with hammer

3: pieces of the material covering the bolts and nuts

4: a nut still covered, measuring 1 3/8" across

5: a nut after the covering layer has been knocked away, measuring 1 1/4" across

So there is 1/16" (~1.5mm) of covering all around (i.e. adding 1/8" to the diameter). The material looks ferric and is quite brittle. I can easily break it up with my hands.

Has anyone seen this kind of covering on top of keel bolts? The boat is from 1962, so it's quite possible that this method is not being used any more nowadays.

Also, looking at the bolts and nuts now that this layer of material is off, they don't look so bad after all. I feel tempted to thoroughly clean them, paint them with suitable anti-rust paint, and then cover them again with the same material, or whatever is being used nowadays.

What are everyone's thoughts on this?
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Old 02-05-2016, 15:50   #2
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Re: What is this protective covering on my keel bolts?

I think you are just "peeling" the rust layers off
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Old 02-05-2016, 16:29   #3
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Re: What is this protective covering on my keel bolts?

I call that protective coating iron oxide.


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Old 02-05-2016, 17:02   #4
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Re: What is this protective covering on my keel bolts?

Those are dinky little washers for keel support
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Old 03-05-2016, 08:41   #5
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Re: What is this protective covering on my keel bolts?

The washers didn't start out as dinky. They are usually the first to go.
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Old 03-05-2016, 08:57   #6
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Re: What is this protective covering on my keel bolts?

Thanks for the replies. I doubt that this is simply rust, for following reasons:

1. After removal, the nuts and bolts underneath are perfectly shaped. If it were rust, the corrosion would likely have damaged the nuts unevenly, but these ones have straight surfaces all around.

2. The material on top of the nut came off in clean pieces with a more or less smooth surface on the inside. To me that looks like it is a separate piece from the nut/bolt.

3. Rust breaks off in red/brown layers. This stuff is not in layers, and not red/brown.

To me it looks like the nuts/bolts were encapsulated with something to protect them.
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Old 03-05-2016, 09:37   #7
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Re: What is this protective covering on my keel bolts?

mexican locktight.
needs removal out of water and replacement is over time.
install new bolts and nuts and washers and watch em over time appear exactly as they are now.
my chainplate bolts were grade 8 when i installed em, and before i left barra de navidad for mazatlan, i replaced with brand new stainless ones. they look nasty--no locktight on em. the locktight takes 3 yrs for grade 8, and longer for stainless.
yes stainless rusts.
btw, mine corroded evenly all around and appeared perfectly round when cut off.
they may have been encapsulated, so the rust , err locktight, came off in flakes with the wtf as well.
mine were not encapsulated, but did it all by selves. gotta love grade 8 for chainplate fasteners. makes for lovely vertical racing stripes.
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Old 03-05-2016, 09:39   #8
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Re: What is this protective covering on my keel bolts?

Whether this is rust (my guess) or a protective coating, your keel bolts, nuts and washers appear to have reached the end of their safe and useful life. These are likely "J" bolts that were cast in to the keel. They can be replaced but it is a fairly extensive and costly job.
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Old 03-05-2016, 09:40   #9
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Re: What is this protective covering on my keel bolts?

Not positive from the pictures, but looks like it could be, 'COAL TAR' poured over the bolts or 'COAL TAR EPOXY' these have been used on steel in the past to reduce corrosion.
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Old 03-05-2016, 10:36   #10
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Re: What is this protective covering on my keel bolts?

Quote:
Originally Posted by geoarch9 View Post
Not positive from the pictures, but looks like it could be, 'COAL TAR' poured over the bolts or 'COAL TAR EPOXY' these have been used on steel in the past to reduce corrosion.
Could be, or zinc or a nickle coating. We used anhydrous lanolin to keep keel bolts away from all sorts of stuff. Used it on a lot of galvanized stuff. Also had a tub of zinc oxide used for dipping bolts to keep threads from galling. The zinc oxide will dry out over time and look similar to your pics.

BTW if your going to take off the nuts, saturate the nuts with either wd-40 or a penetrating oil for about a month. They should come right off without hurting the threads.
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Old 03-05-2016, 13:12   #11
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Re: What is this protective covering on my keel bolts?

Skylark is a 1973 Pearson P-36-1. Bronze "J" bolts cast in a lead keel. I wanted to drop the lead and rebed it, but someone, I suppose Pearson, poured polyester resin all over the keelbolts in an effort to prevent leaking.

In the end, the keelbolts are "glued" into the holes in the bilge. I used a core saw to try to "free" the keelbolts, but the core saw just melted the polyester resin and when we stopped turning it, but resin cooled and "locked" the core saw in position.

The end result is that I am now sure the the lead piece of the keel isn't going to fall off.

You can just add more threaded rod by tapping into the metal of the keel. I think that is called "sistering". Will be a hell of a lot cheaper than buying a new keel or having Mars Metal rectify your problem.
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Old 03-05-2016, 13:15   #12
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Re: What is this protective covering on my keel bolts?

WD 40 is not a penetrating oil. I would suggest PB Blaster or a 50/50 mix of acetone and automatic transmission fluid. Practical Boatowner (I think) compared all the penetrating fluids and the 50/50 was right up there with PB Blaster.
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Old 03-05-2016, 13:29   #13
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Re: What is this protective covering on my keel bolts?

Quote:
Originally Posted by geoarch9 View Post
Not positive from the pictures, but looks like it could be, 'COAL TAR' poured over the bolts or 'COAL TAR EPOXY' these have been used on steel in the past to reduce corrosion.
This is what I was thinking as well.

And despite the fact that it may (or may not) have protected the nuts, bolts, & washers, for some time. They definitely look ripe for replacement. Especially as whatever is passing for a washer, underneath of the nuts, looks more like layers of powder & flaked off bits of corroded material.
So that even were the nuts & bolts sound, there's not enough support underneath of them for them to do their job of holding the keel on.
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Old 03-05-2016, 23:06   #14
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Re: What is this protective covering on my keel bolts?

Thanks again for all the useful comments. It's always great to be able to learn from those more experienced than myself. I've never heard of coal tar but what I see has the look of black coal so that could well be it.

One boat guy here suggested that I can avoid more drastic measures (such as keel removal) by strengthening the keel support in the bilge. Specifically, he suggested making a mould of the bilge section that includes the bolt and nut, one for each bolt, about 2-3 inches wide, then have a steel piece machined for each bolt, which will then be fit snugly into the bilge with the bolt passing through it, and welded to the bolt on its top side. He reckons having this machined in China will not cost much (I'm in Macau which is on the doorstep of China), and could extend the life of the keel support by another 10-15 years.

Any opinions on this suggestion?

I think you can tell that I am really trying to avoid more major operations, such as removing the keel, but of course I'm also concerned about safety.

By the way, the designer/builder (van de Stadt) informed me that the keel is iron with the bolts passing through it from the bottom of the keel up. Just wanted to mention this in case it makes any difference.
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Old 04-05-2016, 06:55   #15
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Re: What is this protective covering on my keel bolts?

Think you will find the keel has flanges on each side which the bolts go through, not through the middle of the keel. Most common method with a cast iron keel. If that is the case, you have a simple job of finding the bolt heads, knocking the bolts out of the flange, and getting new bolts.

If the bolts actually go through the keel, you are screwed and made a major mess of things. Then you got to somehow drill out the bolts, rethread the keel, and redo the whole thing. Chances are you will not get things lined up and have even more leaks. Really a hopeless mess.

Usually if you got leaks coming through the keel bolt area, and the hull is not cored, then simply apply waterproof puddy around the keel seam on the outside of the hull(assuming you cleaned the hull down to bare glass). If you have a cored hull(which i suspect you might) then you are really screwed. At that point, just go cosmetics, sell the boat, and get a better one.
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