Do we really need to coat / protect cast iron keels ?

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zambant

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Lets leave the antifouling issue aside please.
I have a 25 year old Moody with a steel fin keel.
As with most boats of her age her keel is showing signs of rust.
There are no anodes connected to the keel.
So ..... other than keeping the keel smooth to reduce drag are we being overly cautious on continually treating already rusty keels - costing much time and money?
So what do the experts think please ???
Thanks
John
 
Firstly, it is not steel, but cast iron. You have two main choices. The first is to have it blasted clean and then epoxied and Coppercoated or conventional AF. Second is to do the best you can with grinding back rust spots as they appear and priming then AF. Various different treatments available to try and keep rust at bay. Discussed in detail on a thread lower down on this page.
 
Its purely cosmetic, a cast iron keel is not going to waste away to any dangerous degree. I take the view that I make a token effort but accept that its going to be needed every year to some degree. The keel is below water line (mostly) so what does it matter?
 
Yes, don't treat rusty areas on your keel If you don't mind your keel rusting away to nothing, reducing your stability and righting moment, These things are not important to the average club racer or cruiser. And you can always get a two for one deal on new cast iron keels in your local Sainsburys or tesco.

So most definitely a waste of time money and effort maintaining your keel. As is servicing winches, scrubbing off, painting varnishing engine servicing, and many other yachting boat jobs. Your wife is probably correct. You're wasting time and money on that boat that's better spent in the house minding the kids and supporting her after a glass of wine online shopping habits

So, don't do anything about those rusty spots on the keel...
 
ghostlymoron said:
Its purely cosmetic, a cast iron keel is not going to waste away to any dangerous degree. I take the view that I make a token effort but accept that its going to be needed every year to some degree. The keel is below water line (mostly) so what does it matter?
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That's exactly what I am wondering....forget how to protect it....is it really worth the effort ???
25 yrs and its still got loads of metal left......
 
PabloPicasso said:
Yes, don't treat rusty areas on your keel If you don't mind your keel rusting away to nothing, reducing your stability and righting moment, These things are not important to the average club racer or cruiser. And you can always get a two for one deal on new cast iron keels in your local Sainsburys or tesco.

So most definitely a waste of time money and effort maintaining your keel. As is servicing winches, scrubbing off, painting varnishing engine servicing, and many other yachting boat jobs. Your wife is probably correct. You're wasting time and money on that boat that's better spent in the house minding the kids and supporting her after a glass of wine online shopping habits

So, don't do anything about those rusty spots on the keel...
Click to expand...

Humm .... sarcasm .... ?
 
It's a bit of a bummer when you have a lifting keel .

Particularly if you can see some of it when you wind it up.

The rust in staring you in the face. If you start doing all the stuff you end up with a keel so thick
it gets stuck in the box.

I like being intimate with my keel though . Rather than only seeing it once or twice a season.
 
If the OP can leave aside the question of antifouling paint then he probably can leave the boat in the water long term and so not have to see the rust on the cast iron keel. It is not going tom lose much mass in his lifetime.
However around here you can not leave aside the antifouling paint issue. Fouling grows about as fast as Amazon jungle. So you have to paint the keel at least every season. (some claim every secondseason).
When you get rust on the cast iron keel it flakes off the a/f and weed grows on the spot. So you have to scrub in water often or go slow. So to the OP jkust do what you feel like doing, time will tell if rust is OK ignored. good luck olewil
 
Sorry I can't ignore the antifouling issue. A prime consideration in hull and keel maintenance is whether it's good enough for the paint to stay on and do its job for the the sailing season.
 
Used to live with this "problem" on a T24. Nice iron, bulbed keel which had been encapsulated with resin (may have pre-dated epoxy). Eventually the encapsulation cracekd, so we chiselled and ground off the remainder. Several coats off red lead and then antifouling. Each year there was a little less work to touch it up as the half tide mooring scoured the lot off! Still, the keel never suffered much fouling.

Rob.
 
PabloPicasso said:
Yes, don't treat rusty areas on your keel If you don't mind your keel rusting away to nothing, reducing your stability and righting moment .... snipped
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Well my iron keel weighs 3715 lbs, and in 10 years with a few rust patches wirebrushed off each year, a quick coat of Fertan then zinc primer then AF again and it's probably lost about two ounces of iron. It'll all be gone in 30,000 years at that rate. Oh dear.
 
jwilson said:
Well my iron keel weighs 3715 lbs, and in 10 years with a few rust patches wirebrushed off each year, a quick coat of Fertan then zinc primer then AF again and it's probably lost about two ounces of iron. It'll all be gone in 30,000 years at that rate. Oh dear.
Click to expand...

Rust is heavier than iron, so if you didn't take it off your ballast ratio would improve. :)

Some years ago the paint system on my keel failed when the boat was wintered afloat. OK, the paint may only be cosmetic but the keel looked terrible with the boat in the slings, rust dripping off it onto the quay. There is no way I could have put the boat back in the water looking like that.
 
I find it hard to believe that any practically minded boat owner could ignore such a basic maintenance requirement. Same league as oily engine bays and dirty bilges, I guess.

My boat keeps me safe and gives me much pleasure. Why wouldn't I do my best to keep her in tip-top condition.
 
davidjackson said:
I find it hard to believe that any practically minded boat owner could ignore such a basic maintenance requirement. Same league as oily engine bays and dirty bilges, I guess.

QUOTE]
My boat is in first class condition, clean dry bilges / engine bay and regularly maintained.

We are on a drying mud berth and suffer little fouling on the keel. I only antifoul every 2 years and wash off / scrub the hull a couple of times a year. Leave the boat in the water all year and sail her all year round.

I really do question why I should keep putting expensive poison on my keel to see it flake off a few months later.

In fact I am seriously considering not bothering with antifouling in the future - 30 mins with a pressure washer and garden hoe against the wall 3 times a year - seems as if that will do the trick.

Hence the keel question.
Click to expand...
 
zambant said:
My boat is in first class condition, clean dry bilges / engine bay and regularly maintained.

We are on a drying mud berth and suffer little fouling on the keel. I only antifoul every 2 years and wash off / scrub the hull a couple of times a year. Leave the boat in the water all year and sail her all year round.

I really do question why I should keep putting expensive poison on my keel to see it flake off a few months later.

In fact I am seriously considering not bothering with antifouling in the future - 30 mins with a pressure washer and garden hoe against the wall 3 times a year - seems as if that will do the trick.

Hence the keel question.
Click to expand...

My first boat had a fin keel but had been kept in a drying berth leaning against a pier. At 11 years old the hull had never been antifouled but was painted in coal tar epoxy, in the days when it was still good stuff. The PO used to brush it down about once a month, all that was needed. No rust thanks to the coating system.
 
I spent about 20 years struggling to remove the rust that appeared on iron keels year after year, when I eventually got fed up I started just slapping coats of Primocon over the rust stains about 5 coats on the rusty bits plus an all over coat before antifouling, after a couple of years rust failed to reappear. The solvent they used then allowed overcoating in about half an hour or so. But, back in those days Primocon had a lot of bitumen in it and used to leach through the first coat of TBT. White antifouling was blotchy brown when it dried.
I reckon that there is a simple paint formulation which would be effective over rust on iron surfaces, probably not expensive either but almost certainly much too risky to sell to you diy yachties.
 
vyv_cox said:
Rust is heavier than iron, so if you didn't take it off your ballast ratio would improve. :) :
Click to expand...

Yes, if the rust stays attached to your keel instead of flaking off. Rust distributed around the yard under your boat won't help once she's afloat me thinks. BWTFDIK
 
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