Galvanising a cast iron keel?

[lw395]

Cast Iron, of the standard typical on keels, is often porous.
So it's good to get it dry for a long time before coating it.
Then a phosphate treatment and epoxy, it should stay smooth enough for racing for a few years.
My impala had a lead 'shoe' bolted to the bottom of a cast iron keel, that seemed good, as it took any knocks from drying out etc.

I think a smooth keel makes a big difference to windward.

 

[VicS]

How would one securely attach the lead to a cast iron keel ? Just coating in lead like chocolate doesn't strike me as secure enough with two very different materials.

A new replacement all lead keel would work on traditional one piece fixed keels - it's easy stuff to pour into say a sand mould - but care would have to be taken over one's sums re the new weight, and on the attachment.

Decent galvanising on steel lasts well, and I'm still mystified by peoples' cast iron keels corroding; I wonder if cathodic corrosion is to blame, it's a very inert material but no harm fitting an anode.

Galvanised steel keel plate, 10 yrs old, & cast iron ballast bulb, 36 yrs old;

It was not a serious suggestion.

I had know idea if it could be done successfully or not, The zinc deposited in hot dip galvanising partly I believe alloys with the steel substrate to which it is applied. I believe this alloyed layer is partly responsible for the good protection of galvanising and is why other forms of zinc coating such as plating are not as effective.

Apart from the above lead is in the wrong part of the galvanic series to give the (cathodic) protection that zinc does ........just the opposite in fact.

I would imagine that the corrosion resistance of cast iron very much depends upon its exact composition in particular the free graphite content. That would presumably make the material more susceptible to corrosion, being itself very cathodic, as you suspect.

 

[markhomer]

http://www.omnikote.co.uk/pdfs/Technical-template-MetalSpraying.pdf


had heard of this before , no experience , says more exspensive than galv , but as galv pricing is based on weight where a keel has a very poor weight to surface area ratio, spraying may be nearer in price and sounds like a better job .

personaly i wouldnt bother , infact I dont

 

[Seajet]

Spray galvanising is very poorly regarded, nowhere near as thorough as hot dipping; makes sense to heat the whole job rather than just spray on a thin surface coat if one thinks about trying to get the zinc to adhere properly.