Rust prevention on keels

[Impaler]

Has anyone found a good rust preventer for steel bilge keels? Most seem to last for a season and then it's out with the electric wire brush. How about some of these liquid galvanising paints such as Galvafroid?

 

[Pasarell]

Most keels are made from cast iron and so difficult to stop corrosion long term.
Best way is dry abrasive blasting followed immediately by a good quality penetrating anticorrosive. Cast iron usually has a lot of pits and holes in it and a viscous anticorrosive will bridge over the pits and not make good contact with the surface which will allow corrosion to set in again and blow the coating off.
After the penetrating coat follow up with a proper thickness (it varies by brand) of anticorrosive before antifouling. The anticorrosive coating will normally contain zinc, be difficult to stir properly, and be very heavy.
If you don't want to do all this you have to settle for cleaning as well as you can by hand and a conventional primer that will need frequent maintenance. Wire brushing is not a good way to clean the surface as it tends to polish the rust rather than remove it. You get a nice shiny surface but it will not remove the existing corrosion so when you paint you are just coating over active rust.
Grinding is more effective but on cast iron it is always a bit of a lottery
Good luck!

 

[bumblefish]

Try a needle gun to get the rust off, it will get you back to 'clean' metal and epoxy the metal as it is exposed. immediately!

 

[savageseadog]

Don't try Zinc rich coatings because they will electrolyse and bubble through the upper layers.
If you can do it, blast it. After whatever preparation you've done use a very high build primer, thin the first couple of coats well down and spray it if you can, you need to get the primer into the pores of the iron. Put as much thickness of primer as you can get on. Paint tends to thin on sharp edges so try to round them off and put double coats on them.

 

[Impaler]

Many thanks.

 

[William_H]

My experience watching other people is that even if you put a lot of effort in at haul out painting time you may still have the same rust appearing next year. Some poeple however seem to be lucky.

I think that if you would rather be sailing then a quick grind down, coat of rust treatment then primer and antifoul paint is a viable option.
ie don't spend too much effort on it cos you will be at it agin next year. it just seems to be the price for having a cast iron keel.

Bearing in mind that you will probably bounce the keel bottom on rocks occasionally through the season so exposing bare metal so you will have to retreat each haul out no matter what you do. olewill

 

[capt_courageous]

Hi Dave
Last winter I put some anodes on our boat's keels for the first time. A few people in our club have done it and it seems to help but I won't find out for sure until lift out in October. It works for other bits of metal on boats so hopefully it should be of some use on keels.

 

[Impaler]

William H, hush your mouth....bounce my bottom on rocks? I'll have you know, blah, blah, RYA navigation courses, ex RN..blah....blah...tidal curves...look out in the bows etc....!! Thanks, I think you are probably right and maybe its best not to lose too much sleep over it. I think I will try the anode idea though. Cheers. The only thing I like on the rocks is a stiff gin.

 

[2Tizwoz]

'...ex RN..blah....blah...'

Not on HMS Nottingham then?

Repatriating of the damaged destroyer HMS Nottingham from Australia to UK in December 2002

 

[William_H]

Re Bouncing on rocks. I have a theory that when racing you are really not trying hard enough oif you don't occasionally hit the bottom.
But then myy little boat is easy to unstick in just a few seconds. ie leanb the boat over and use a boat hook to turn it in the right direction and sail away. (usually) olewill

 

[Impaler]

I saw the light and went Para.
The only racing I do is to get to the pub before closing time.