Rusty Keel

[emnick]

Last year I rubbed the keel on our Sadler 32 back to bare metal, I painted it with 5 coats of keel paint, only to find when it came out of the water this year it had started to rust again,anybody had si9milar experience, and how did you manage to get round it.
Thanks in advance

 

[philip_stevens]

My Konsort Duo keels were slurry blasted, and I applied Neutrarust 661 as soon as there was a sufficient rust covering on them. The Konsort I sold last year is still in this area, and the keels are as good as when I put the neutrarust on them 7 years ago.


I put a second coat of neutrarust 661 on my keels. It is a water based rust converter, and the same thing can be obtained from Screwfix Direct as "Rust Converter".

I applied the 661 on my last boat 8 years ago, and looking at her recently (under new ownership) the keels have no rust showing through.

It is the same colour and consistency as double cream, but changes colour to blue/violet/black as it dries and converts the rust.

At it is water based, it can be applied under almost any weather condition - piddling with rain excepted.


I had the bottom slurry blasted with a find mica "sand", and at the same time had them to blast clean the rust and scale from the keels. I left the keels to rust for about 6 weeks to get some rust back on them, and did them for the second time - just to built up the surface a bit and fill in some small rust voids.

As I had "clean" finish keels, I didn't need to wire brush them down again, but if the rust is thick and maybe flaky, you will have to remove some of the build up.

When I did my last boat, I put AF straight on top without primer, and looking at her in the yard, none has flaked off the converter - 7 or 8 years after I did it.

Other treatments require you to take the keels back to shiny metal, and in this country (especially here in the south-west) moisture soon gets back on the metal - before you can apply the treatment.

This reply is a copy of three different posts. Hope it helps you.

 

[Inselaffe]

Hi emnick,

I am going to take out my lifting keel next week to lubricate it and want to clean it up whilst its out, so I am interested in this too, hope you don`t mind me asking a few Q`s too, I don`t want to tread on any toes!

I have done some searches and sifted through quite a few to get the following threads;

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

http://www.ybw.com/forums/showflat.php?C...&PHPSESSID=

leigh

 

[Inselaffe]

Hi philip,

is this the stuff on neutra-rust.com? seems the international section of the company is in the Uk and you can order it direct online?

Also, presumably you leave the surface to rust for a few weeks to get a coating of rust so that when you convert it to the impervious version of iron oxide there is a good layer? ie the converted rust acts like a paint barrier?

Thing is I have to get the boat in the water within about a week at most after treating the keel, which means probably there wont be much rust to convert, what do you think?

Leigh

 

[silverseal]

Neutrarust is I think phosphoric acid based and coverts to iron phospahte which is not water soluble and hence forms a barrier, which is why further oxidation does not take place.

 

[philip_stevens]

If your keels are like mine, cast iron, they will rust within minutes of being slurry blasted clean. As soon as the water dried, rust showed up!! So give it a few days, and there should be some rust showing. I think that in a week, there was sufficient rust on the keels to allow the application of Neutrarust, though I left it for about 3 weeks as I had other thing to do.

The Neutrarust has been on the keels for about two months or so now, and every spring tide, the keels are in sea water. With no other covering, there is no rust showing through the black finish.

If you cannot get Neutrarust, Screwfix Direct do a similar product "Rust Converter".

You may have read on the Neutrarust website that they name some other companies who have nicked their product/formula!! One is in the UK, and may be the one that supplies Screwfix.

 

[riboid]

lack of surface preparation sound the likely cause. with blasting the keel you will create a good profile which is essential for the coatings to adhere. if you cant get a localised blasting machine you can abrade yourself. make sure you remove all traces of corrosion then abrade very rough. this will ensure proper coating adhesion. first use two part primer. (leighs C425 high build zinc phosphate primer) abrade slightly between coats to ensure inter coat adhesion and over coat next day to ensure overcoating times are adhered too. do as many coats as you want but your looking for around 500 microns minimum. this isnt a light fast coating and will fade so you will need to top with top coat for a finish. try maybe leighs c750 comes in white.

 

[riboid]

forgot to say if your looking for an anti fouling coat too you will have to apply a tie coat between your C425 primer (high build phosphate) and then your anti fouling.

spec as follows:

C425 high build primer (2-3 coats abrade between coats and solvent wash)

M535 tie coat - 1 coat

TF500 top coat for finish