My O'Day 23 (1973) had a lot of rust (scale) on the keel last Spring. I scraped it all off, wire brushed it down to clean (as clean as I could get it), primed it with two coats of marine metal primer and then put on two coats of bottom paint. When boat was hauled out last Fall the bottom paint was almost all gone and keel was all rusted again. Did I do something wrong or is there another method that would give better results? My boat is kept on a slip in salt water. Thanks, JT
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Keel Painting
Cast Iron keels are the worst decision ever made by boat manufacturers. They are cheap but they rust and don't absorb shock in a grounding instead they are brittle and fracture. I have read that barrier coating metal underwater works and am going to try it on my keel (lead) on my 35. It might work to keep the water away from the metal, as long as the metal is exposed to the water it will not keep good adhesion with the paint. there is enough oxygen in the water to allow the cast iron to oxydize (rust).
Cast Iron keels are the worst decision ever made by boat manufacturers. They are cheap but they rust and don't absorb shock in a grounding instead they are brittle and fracture. I have read that barrier coating metal underwater works and am going to try it on my keel (lead) on my 35. It might work to keep the water away from the metal, as long as the metal is exposed to the water it will not keep good adhesion with the paint. there is enough oxygen in the water to allow the cast iron to oxydize (rust).
JT ,
I know you will not like this but you may need to do it again. When you primed it, then put antifoul paint, the antifoul paint has copper and the keel is case iron. You have created a galvanic nightmare. David was right. Take back down to bare metal then start again with multipul barrier coats then antifoul. Better hurry, it is a nice day here. r.w.landau
I know you will not like this but you may need to do it again. When you primed it, then put antifoul paint, the antifoul paint has copper and the keel is case iron. You have created a galvanic nightmare. David was right. Take back down to bare metal then start again with multipul barrier coats then antifoul. Better hurry, it is a nice day here. r.w.landau
Keels
JT- Before you go cursing your boat for its iron keel try fixing it one more time. I redid my keel last spring and I hauled it this fall without rust except where I grounded it and scraped off the coats. Can't blame the iron for my failures to navigate competently.
While your are probably pretty dejected about the prospect of doing this again, you also probably don't have as much work to do. The rust is most likely pretty superficial, and there is probably not a lot of scaling. So, stripping it down again isn't going to be the nightmare it was last time. This time, after you strip it try this. You probably already know some of these steps, but I'll go through what I did top to bottom anyway. (On fixed keel boats) Remove the bottom paint for three or four inches on the keelson all the way around the keel to hull joint. Grind back to fresh gel coat. The goal is to create a strip of clean hull so that when you coat the keel in epoxy you can overlap on to the hull for a good joint. Grind and sand the keel until as much rust as possible is gone. Don't cheat and leave the areas where the paint didn't come off; it'll cost you in the end. Wear proper protection and take care with your residue. After you've removed as much rust as possible with the grinder, use naval jelly or the equivilant to remove the remainder. Wash with fresh water and coat with a metal-lock type primer immediately. If you wait overnight you will have to prep it again. Using Interlux Fiberglass wash or similar wash down the area of hull you washed earlier. Mix up a batch of epoxy, my preference is for West System. Paint the keel with the epoxy. Make small batches and paint small areas, and then another small batch and small area until the keel is coated. If you haven't worked with epoxy before, there is no magic to it, but you don't want to make big batches because the will get very hot as they cure in the cup. Paint the entire keel and overlap onto the area of hull you've stripped and prepped (on fixed keel boats). The hardest part of this is to figure out how to get either the bottom of the keel, on fixed keel boats, or to drop the board and get the top of the blade with swingers. You're on your own here. I found that I could get to all but a couple of inches on the bottom of my keel and had to content myself with that. This spring I will finish the job because the boat is blocked differently. Once the epoxy has started to cure (its sticky but not still wet) paint another layer on. It is important to do this while the previous layer is still curing because later you will have to reprep because of the waxes that are released at full-cure. Once the second layer is in gel phase, I would mix up a batch of epoxy with fairing compound and spread it on the keel. This is not necessary for rust prevention, but fair keels are faster and point better. Go with a thin layer of fairing mix and add another layer in its gel phase. When they've cured, sand the keel fair. Finally, bottom paint. At this point you have a solid layer of plastic around the keel. If you've prepped correctly, you won't have to do this again for a really long time. Also, if you've gotten good adhesion, even if part of the coat falls off, only that are will be affected and you can repair it the next year. Justin - O'day Onwers' Web I am assuming he
JT- Before you go cursing your boat for its iron keel try fixing it one more time. I redid my keel last spring and I hauled it this fall without rust except where I grounded it and scraped off the coats. Can't blame the iron for my failures to navigate competently.
While your are probably pretty dejected about the prospect of doing this again, you also probably don't have as much work to do. The rust is most likely pretty superficial, and there is probably not a lot of scaling. So, stripping it down again isn't going to be the nightmare it was last time. This time, after you strip it try this. You probably already know some of these steps, but I'll go through what I did top to bottom anyway. (On fixed keel boats) Remove the bottom paint for three or four inches on the keelson all the way around the keel to hull joint. Grind back to fresh gel coat. The goal is to create a strip of clean hull so that when you coat the keel in epoxy you can overlap on to the hull for a good joint. Grind and sand the keel until as much rust as possible is gone. Don't cheat and leave the areas where the paint didn't come off; it'll cost you in the end. Wear proper protection and take care with your residue. After you've removed as much rust as possible with the grinder, use naval jelly or the equivilant to remove the remainder. Wash with fresh water and coat with a metal-lock type primer immediately. If you wait overnight you will have to prep it again. Using Interlux Fiberglass wash or similar wash down the area of hull you washed earlier. Mix up a batch of epoxy, my preference is for West System. Paint the keel with the epoxy. Make small batches and paint small areas, and then another small batch and small area until the keel is coated. If you haven't worked with epoxy before, there is no magic to it, but you don't want to make big batches because the will get very hot as they cure in the cup. Paint the entire keel and overlap onto the area of hull you've stripped and prepped (on fixed keel boats). The hardest part of this is to figure out how to get either the bottom of the keel, on fixed keel boats, or to drop the board and get the top of the blade with swingers. You're on your own here. I found that I could get to all but a couple of inches on the bottom of my keel and had to content myself with that. This spring I will finish the job because the boat is blocked differently. Once the epoxy has started to cure (its sticky but not still wet) paint another layer on. It is important to do this while the previous layer is still curing because later you will have to reprep because of the waxes that are released at full-cure. Once the second layer is in gel phase, I would mix up a batch of epoxy with fairing compound and spread it on the keel. This is not necessary for rust prevention, but fair keels are faster and point better. Go with a thin layer of fairing mix and add another layer in its gel phase. When they've cured, sand the keel fair. Finally, bottom paint. At this point you have a solid layer of plastic around the keel. If you've prepped correctly, you won't have to do this again for a really long time. Also, if you've gotten good adhesion, even if part of the coat falls off, only that are will be affected and you can repair it the next year. Justin - O'day Onwers' Web I am assuming heSandblast?
The reason it probably rusted again so soon was because you didn't (couldn't) get all the rust off. Jason's method is great, but I might add that sand blasting might help to remove ALL the rust down into the 'pores' of the cast iron. Then finish the job as Jason stated. Russ
The reason it probably rusted again so soon was because you didn't (couldn't) get all the rust off. Jason's method is great, but I might add that sand blasting might help to remove ALL the rust down into the 'pores' of the cast iron. Then finish the job as Jason stated. Russ
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