Rust on Keel

HunterWanderer,

I tried 709 epoxy over Primocon and it was a disaster, it seemed the epoxy got chipped and trapped water against the keel - the boat is on a half tide mooring so usually dies a bit between tides, and trapped water against the keel seemed to finish it off !

Dulux Metalshield and primer are not particularly high zinc AFAIK, the new keel is galvanised though - as the old one was originally.


I have tried Galvafroid very high zinc treatment in the past, it's obviously good stuff, one feel by the weight of the tin !

But nowhere near as effective as Metalshield in my experience; ' effective ' = no rust and good as new when the boat comes ashore for the winter.

I'd just point out in defence of the boat there's a known ' area of accelerated steel corrosion ' at my mooring.
 
Vyv,

don't know if you are referring to me, but I'm well aware of the difference !

The A22 keel plate is tapered 3/4" mild steel, originally galvanised.

THe ballast bulb on the end ( which doesn't corrode significantly ) is cast iron.

I do fit a faired button anode on the part of the plate which remains below the boat when the keel is raised.
 
oldsaltoz said:
Cast Iron is not the best material, it's full of voids and contaminants when new, I have seen pockets of sand in keels.:)
Click to expand...
Echoing one of the RYA how to paint your boat books. The cast iron could be so full of contamination that nothing will work for long so not much point spending lots money or time on it. Or it might be quite clean so a good epoxy might last for years.
On a steel boat I've had good results with ameron sealer on hand prepared metal as a first tie coat, takes ages to go off and seeps into absolutely everything, but expensive.
http://www.marineandprotectivecoatings.co.uk/sheets/ameron/Amerlock Range.pdf

Unfortunately to know what works best you need to be about 300 years old, other wise you have no idea if your perfect "this is how you should do it everyone listen" works any better or worse than the multitude of other varieties of prep /paint on that particular piece of metal.
This probably isn't any use for a keel as it would take a month to do next side, but if it's only a few bits here and there then might be worth a look.
http://www.cirrus-systems.co.uk/perago-rotating-blaster-discs-2 again expensive.
The best way I've found to see you if your prep method is any good is to be somewhere in the tropics and spray some phosphoric acid like ospho on the steel. If it pops and fizzes then there's still iron oxide in there. Then wash and paint, it seems to last better to iron phosphate than to iron oxide.

Or just clean and slap some hammerite on there, go sailing and do the same next time :)
 
No one tried VC Tar - I had a 42 ft steel boat shotblasted with a holding coat put on, and then used VC Tar - didn't bother with antifoul and was remarkably clean when taken out after 2 years and then after 3 years and very minor rust stains creeping through.
 
In my case it was on a fin keel, a lifting one which will always give treatments a hard time.

When the boat came ashore for the winter there was slight rust uniformly coming through, so not just at scrape points in the casing; it's a while ago and I don't remember the primer, but I'm alway very careful about preparation and primer, as obviously otherwise it's all a waste of time.
 
How do you make that out then ?!

If you read what I've said you'll see that my mooring has a known problem, I've had the Marine Metallurgy Unit of Portsmouth Uni' come around as they're investigating this; I've always suspected the nearby main power feed to Hayling Island.

It affects any steel structures in the area and keeps us busy checking moorings but it extends to POrtsmouth Harbour.

As for the A22 keel, well they're over 30 years old now, and we have new keels available on the shelf, newly made by the original foundry, the ex-M.D. has funded a batch and has vowed we will always have at least one keel available on the shelf.

How many other even new boats can offer that ?

All lift keel boats require maintainence of the keel plate, either by storing the boat up high or by digging a pit; if I'd caught on sooner I might not have had problems but what the hell, my boat has a newish keel now.
 
Twister_Ken said:
Think i said this on a similar thread recently.

I've used Owatrol oil on rusty wrought iron gates (close to the sea, so salt laden environment, but obviously not immersed). Worked well, and the bits Ididn't get round to overpainting are still rust free about 30 months later.

http://www.owatrol.com/index.php?langue=en&page=produits-rustol-owatrol
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+1 . Used it on the keels and it was over two seasons before a few small rust patches appeared which got retreated and overcoated with anti fouling and fine since .You can buy Owlatrol much more cheaply from a decorating wholesaler than the chandelries
 
Why spend time grinding? Ensure there is no loose rust using a good wire brush and then use a suitable under water anticorrosive primer such as Blakes Keel Prime. Ensuring sufficient coats are applied. These products generally do what they say on the tin. I haven't had a problem with rusting keels as a result of using these products.
 
ripvan1 said:
No one tried VC Tar - I had a 42 ft steel boat shotblasted with a holding coat put on, and then used VC Tar - didn't bother with antifoul and was remarkably clean when taken out after 2 years and then after 3 years and very minor rust stains creeping through.
Click to expand...

Years ago I found VC Tar to be superb but the original, distilled coal version of the tar was banned due to concerns over the organic solvents it contained. The replacement is not as good in my experience. I don't know when the change came, 15 years?
 
vyv_cox said:
Years ago I found VC Tar to be superb but the original, distilled coal version of the tar was banned due to concerns over the organic solvents it contained. The replacement is not as good in my experience. I don't know when the change came, 15 years?
Click to expand...

That's the answer then, my use of it was in 2001/2 and I had bought up a few tins at a b/jumble IIRC.
 
Hi Seajet,
The A22 I'm doing up has the keel stuck in the up position.
Before I took it out of the water it had sat in the up position and not sailed for a couple of years by the previous owner. (He assures me it went up and down no problem before it was left).
Tried to get it down with gentle persuasion tapping it at the top of the plate. Seems to be alot of corrosion but as you know I can only get to the plate at the top foot or so - I can get a saw into the top and have gently tried to remove the rust but not very successful. Any thoughts? Maybe pouring down some type of rust breaker from above?
Also The boat is sitting on its trailer with the 4 pads and keel bulb taking the weight, I have tried jacking the hull up from one end but it's putting too much weight on the other 2 pads and the hull was indenting - so I stopped that. Any idea where the best lifting spots are on the A22 as I may have to get a crane in!
 
Hi Skippy 36,

it's possible for rust flakes to jam the keel up if left uncared for over a period of time; I know someone who made a blade about 4' long and attacked the sides of the keel casing from inside the boat; beware it's a close fit, don't damage the grp casing !

Afloat, if the keel begins to stick one can usually persuade it to drop by lifting as high as it will go ( bearing in mind the top of the casing, visible inside by looking aft at the keel leading edge ) then dropping it a few inches at a run so the wire goes slack; only a few inches at a time mind.

It's also possible to cause jamming if too much paint is applied to the keel plate.

The lift or trestle points are, under the forward bulkhead - note NOT the one visible through the windows, that's the main bulkhead; the fwd one can be seen if peering forwards through the forward window, can also be located surprisingly easily by tapping on the hull.

The aft trestle point is under the sub-bulkhead at the foot of the port quarter berth; on a standard boat this is 100" aft of the forward bulkhead.

This is for trestles; normal wide webbing crane lifting slings are not at all critical, but beware the forward one doesn't slip off up the rocker of the forward hull - if in any doubt tie the slings together, one side would do.

Sounds like you really need a look at your keel plate, all lift keelers suffer if kept on a trailer; I can supply diagrams to build simple but effective high winter trestles, which allow lowering the keel for inspection & maintainence, if your club or yard can lift her on & off them.

My chum who rased his boat on a trailer knew the trestle points, and his trailer happened to come with particularly large load spreading pads & acro style threaded legs; obviously one leaves the weight of the keel on the central trailer tray, with the winch slack; that might require someone inside co-ordinating in your case, if you can free the keel off a bit to start with...

Andy
 
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