Cleaning up a cast iron keel

[Justin_NSA]

Here's my keel just before I sanded it to 'degloss' it for bottom paint. I used POR15. Followed all of their instructions. I got as much as I could with grinders. I'll have to do the bottom in the Fall when I block it up. I can report out when we haul her for the winter. Meantime, it's getting closer to sailing!!

 

[pateco]

You could try one of these

Eastwood Liquid Media Blaster

 

[isaksp00]

Justin - let us know over time how the POR15 worked, I used it, and also their prep liquids. It said to use hot water for one, and that is tough to really do in a boat yard, but I did my best. It went on very glossy like yours. I only did one coat, I think. After about 2 yrs, there were rust blisters, some maybe an inch or so across. One of these seasons I will grind out these spots and maybe reapply, except I am not sure if the newer POR15 will stick to the older stuff - did the company advise you on that?

 

[Justin_NSA]

I got hot water for the cleaner degreaser from a close by restroom. Used their Prep on the bare metal keel. I don't know if it sticks to anything else. Time will tell how it works.

 

[Jackdaw]

The pros at Marine Fiberglass in Minneapolis are doing this to BlueJ as we speak:

Soda Blast to bare iron and gelcoat
Ospho on the Iron keel
InterProtect 2000E on the keel ASAP to seal (picture taken here)
Thickened epoxy to fair the keel
InterProtect 2000E on bottom
VC17 race paint

I would have loved to do this myself, but the lifting keel and the size of the boat made it a job for pros. Plus I trust these guys, they're the best.

 

[Gunni]

That is by the book, and all the proven materials! Not sure if VC requires a hot coat. I will never sand off bottom paint again. Blast only.

 

[Justin_NSA]

I am not sure if the newer POR15 will stick to the older stuff - did the company advise you on that?

I misread your question The people at POR said you can recoat the POR15, you just have to rough it up for adhesion.

In all the readings I've found on how to seal a cast iron keel, for every person that says one way is the only way, another person will say a different way is better. The only thing I know for certain is, if you have to get all the rust off, blasting it (no agreement on soda or sand) is the only way to get into every nook, crack, hole etc. Hence the phosphoric chemicals go on first. Even Ospho says you don't have to remove all rust...

"OSPHO is a rust-inhibiting coating - NOT A PAINT You do not have to remove tight rust. Merely remove loose paint and rust scale, dirt, oil, grease and other accumulations with a wire brush - apply a coat of OSPHO as it comes in the container - let dry overnight, then apply whatever paint system you desire"

 

[Sefuller]

I did my cast iron keel in 2006. I used an angle grinder with 36 or 40 grit to remove all the old material, then a wire brush in a drill. I washed with fiberglass solvent wash 202 and coated with thinned Interprotect immediately. I did one side at a time, so from final wire brush to solvent to epoxy was probably under 20 minutes. I did a total of 5 or 6 coats of Interprotect on the keel, and I have not had any recurring rust on my keel with the exception of a couple areas the last two year where it appears water may be getting into the keel/stub joint, which I never faired. (The keel probably has 5200 between the stub and keel - as far as I know the keel has never been off). I have been debating whether I should cut out as much sealant as I can from the perimeter with an oscillating saw and re-sealing or if I am better of just leaving it alone. I am a little nervous that if there is rust on top of the keel, the new sealant won't adhere well - not sure if that's something I should be concerned about or not.

 

[Gunni]

I have been debating whether I should cut out as much sealant as I can from the perimeter with an oscillating saw and re-sealing or if I am better of just leaving it alone. I am a little nervous that if there is rust on top of the keel, the new sealant won't adhere well - not sure if that's something I should be concerned about or not.

The fix is to hollow out the hull-keel joint, clean the rusty keel and apply your underwater epoxy primer to the hollow then apply your flexible sealant to the joint hollow. I wouldn't use an oscillating saw. I got pretty good, long lasting results with a screw driver, wire brush and some spare MAS epoxy. Scrub the wet epoxy into the joint with the wire brush.

 

[Justin_NSA]

Bottom paint is on. Craning her into the water tomorrow! Woohoo!

 

[jeff356]

I just had the iron keel on my Hunter 34 soda blasted. It must be done correctly, so I let the marina do it. After blasting it, they immediately applied two coats of Petit Rust Lock epoxy. Then they dug out the void between the keel and the hull and filled/faired it. It's a big job; cost me close to a thousand.
Barn-dog

Also in the Middle River area and contemplating taking my hull all the way down next year. Which marina are you at and was it marina staff of an external company that come in? BTW am at Bowleys right at the mouth.
Thanks,
Jeff

 

[StephenD]

Regarding Pettit "Rustlock" treating before epoxy coats, I found what seemed like contradictory information in their data sheets and tech bulletins, in that the general instruction for underwater steel says that a minimum of 3 coats is advised but the keel restoration instruction advises only one coat prior to epoxy overcoating. Since I have a gallon on hand and a smallish keel I called and asked the Pettit tech rep if additional coats are permissible and he said yes, do several coats it is potentially beneficial and would not hinder the attachment of the subsequent epoxy layers.
Of course he cautioned me to adhere strictly to the proscribed time limits.
As an aside sanding the failed epoxy off the (Hunter 31/2008) keel is one of the most tedious boat tasks I've ever done. I would have contracted a sandblaster but I'm in a time crunch.

 

[RitSim]

I did a badly rusted keel on a 26' boat. Grinding is only good for surfaces that are flat with few rust penetrations. However for rust penetrations, I used a needle scaler. Prep and sealing as described above is key. After sealing, I faired any rust divots and then finish coated as needed. Blasting is the premier method.