Spade anchor corrosion

[Benz]

What if they poured in molten iron, maybe colloidal graphite or some such rust-resistant sort? Would the weight difference be enough to ruin the benefit? Would the greater cost of melting iron (which is otherwise cheap) be more than the greater cost of buying lead?
What about a solid cast-steel head with the same sort of welded shank?

[rslifkin]

Originally Posted by Benz

What if they poured in molten iron, maybe colloidal graphite or some such rust-resistant sort? Would the weight difference be enough to ruin the benefit? Would the greater cost of melting iron (which is otherwise cheap) be more than the greater cost of buying lead?
What about a solid cast-steel head with the same sort of welded shank?

They'd likely have to change the size of the ballast area to get enough weight with different material.

Take a look at the Vulcan for a different way to design a similarly shaped anchor. It's got a solid steel fluke (including steel ballast) and a welded on shank.

[SaltyMetals]

Lead is about 50% more dense than steel so the steel insert solution would not work.
Andrew

[Jammer]

Following with interest.


One way to look at the problem is that the lead must be added after the anchor is galvanized, because the hot-dip galvanizing process would otherwise melt the lead.


I wonder whether electroplating the completed anchor -- after galvanizing and after the lead is poured -- would not provide a sufficient coating over the lead to prevent corrosion. The plating could be focused on the lead in particular to conserve plating salts - there are many ways to do this.


I would think that to be a more practical and reliable approach than trying to cover the lead with some sort of nonconductive coating (paint/plastic).

[Quebramar]

Originally Posted by Jammer

…. trying to cover the lead with some sort of nonconductive coating (paint/plastic).

Would a good layer of Sika do the job?

I’ll check mine this WE and see what could work

[Benz]

Originally Posted by SaltyMetals

Lead is about 50% more dense than steel so the steel insert solution would not work.
Andrew

Couldn't they use 50% more steel? The lead by no means fills the hollows.

[rslifkin]

Originally Posted by Benz

Couldn't they use 50% more steel? The lead by no means fills the hollows.

As long as they can fit enough, yes.

[markxengineerin]

Based on this thread, I chose G-Flex epoxy as an attempted barrier to keep water out of the lead/steel joint, hopefully will mean the lead never gets wet period.

Process was
1) Clean with wire brush on drill as best possible
2) Blow out debris
3) Coat area with G Flex, acid brush
4) Wire brush again, through the epoxy. I could see the lead getting shiny, so that part worked, but didn't seem to get enough pressure on the galvanizing to do the same.
5) Coat area with peanut butter thickened G Flex (collodial silica), with a fillet in each corner done by gloved finger
6) Replace stainless bolt/nut with titanium, using excessive amounts of TefGel, mostly as galling prevention
7) Last steps no done yet, but attempt to wire brush/sand the result and either paint gray, or coat with 5200 then paint, not sure yet.

Hopefully this at least delays the problem

[Jude.rich]

I have a 25kg spade which was very rusty. It wasn’t a big job to heat the tip to remove the lead. I did this with a small handheld propane torch, it mostly came out in one lump once the edges of the lead had melted. I also cut away and replaced the steel sections on the back side of the flukes and welded the removable shank to the fluke. Then took it in to have it fully sandblasted and hot dipped galvanised. I remelted the lead back in and after five years it still looks good as new, possibly better as it has a good thick galvanised coating.
I’m very happy with the anchor and its holding capability and I felt was well worth the small cost to refurbish, from memory no more than about US$60.

[markxengineerin]

Here in the US, that sounds like it would cost a lot more than $60. This was in NZ?

I'm glad to hear it's working out for you- how old was the spade when you determined it needed a rebuild? It would go against the theories in this thread if it lasts longer after the rebuild than it did previously, as you would not have corrected the root cause with the procedure you described. Or maybe galvanizing thickness comes into play, too. Too many variables.

[Shaneesprit]

Originally Posted by SaltyMetals

tKeithLu,
I was hoping this thread would have flushed out some other Spade owners who had found other solutions.
I dont think the SS bolt takes much force. I think it is simply there to make sure the shank does not disconnect.
Andrew

I am unfamiliar with the anchor type (photo would be nice) but assuming the bolt in question holds 2 pieces of metal together. It is not the bolt that takes the strain, but the surface friction it creates between the two pieces that takes the strain.

[Jude.rich]

Originally Posted by markxengineerin

Here in the US, that sounds like it would cost a lot more than $60. This was in NZ?

I'm glad to hear it's working out for you- how old was the spade when you determined it needed a rebuild? It would go against the theories in this thread if it lasts longer after the rebuild than it did previously, as you would not have corrected the root cause with the procedure you described. Or maybe galvanizing thickness comes into play, too. Too many variables.

Hi there, the PO purchased the spade, I think about 2007, so it was only about 10years old when I refurbished it about 5 years ago and it still looks as good as new. I think it is the quality of the galvanising that is an issue? In any case for the sake of <$100 I’m happy to do it again, for what has proven to be a very good anchor. I did all the work myself, excluding the sand blasting and galvanising, hence why the cost was relatively low.

I’ll post some pictures if interested

[Jude.rich]

Here are some before, during after refurb photos

[svonadym]

Following with interest as I intend (intended?) to purchase a galvanized Spade anchor for my primary in the next year or so. This is the first I've heard of this issue. I hope there's a longer lasting solution other than re-galvanizing every ~5 years.

[Capt Gill]

My 55# galvanized Spade, which I purchased new a little over a year ago, has some type of epoxy covering the lead, so perhaps that took care of the problem. I would send a photo, but I won't be on my boat for a week or so.