Treating Rust in Cast Iron Keel
Dec 21, 2017 0:00:22 GMT
Post by eggsi on Dec 21, 2017 0:00:22 GMT
FIXING RUST IN CAST IRON KEEL
I have a Jeanneau 31 with a cast iron keel which developed multiple rust spots that were evident at annual haul-out anti-foul time and became progressively worse each year. I tried many quick fixes but none seemed to work.
After reviewing many systems at the Hobart WBF, I was impressed with the Ferronite/ Bote Cote system and carried out a trial on a cast iron plate which I left at the water’s edge. After 4 months of daily tidal washing cycles, it performed perfectly with no hint of rust appearing. This gave me confidence to go to the effort involved to apply the product to my keel.
1. Remove old antifoul. This step was delightfully easy by applying the “Lemon Peel” stripper product constructionepoxy.com.au/lemon-peel After applying a very thick layer, I covered it with plastic overnight and the old stuff just literally fell off with a paint scraper.
www.23hq.com/Jeanneau/photo/38992379/original
www.23hq.com/Jeanneau/photo/38992381/original
2. Prepare the surface. I then removed the majority of some old red-lead primer and grey epoxy filler with a combo of sharp scraper and rotary wire brush. There were many (around 100) pockets of rust which appeared as dark stains, some big (50c coin) and many small (pencil diameter), which I dug out with a sharp point and then ground out with rotary wire brush. The wire brushing left areas of bright metal which is not ideal for the feronite primer as it needs some surface rust to react and bind to, so I brushed on some hydrogen peroxide to promote surface rust blooming. The next morning I hosed the whole keel down with a pressure washer.
www.23hq.com/Jeanneau/photo/38992382/original
3. Apply Feronite primer. This turns dark brown/ black after it reacts with the rust.
4. 2 coats of the Bote Cote epoxy were then applied as per instructions.
5. The next day I brushed out the rust pockets with acetone (styrene would be better) and filled all the holes with epoxy paste that you mix as per instructions. After this cured hard overnight, I sanded the whole keel to remove any high spots and was left with a reasonably smooth surface. I then applied another 2 coats of Bote coat making 4 coats in total and fared this off again ready for the usual primer and anti-foul.
Previously there were rust spots starting to appear within a month but this time there is nothing at all after diving on it 2 months later. I will monitor next year and update this post with the performance.
I have a Jeanneau 31 with a cast iron keel which developed multiple rust spots that were evident at annual haul-out anti-foul time and became progressively worse each year. I tried many quick fixes but none seemed to work.
After reviewing many systems at the Hobart WBF, I was impressed with the Ferronite/ Bote Cote system and carried out a trial on a cast iron plate which I left at the water’s edge. After 4 months of daily tidal washing cycles, it performed perfectly with no hint of rust appearing. This gave me confidence to go to the effort involved to apply the product to my keel.
1. Remove old antifoul. This step was delightfully easy by applying the “Lemon Peel” stripper product constructionepoxy.com.au/lemon-peel After applying a very thick layer, I covered it with plastic overnight and the old stuff just literally fell off with a paint scraper.
www.23hq.com/Jeanneau/photo/38992379/originalwww.23hq.com/Jeanneau/photo/38992381/original2. Prepare the surface. I then removed the majority of some old red-lead primer and grey epoxy filler with a combo of sharp scraper and rotary wire brush. There were many (around 100) pockets of rust which appeared as dark stains, some big (50c coin) and many small (pencil diameter), which I dug out with a sharp point and then ground out with rotary wire brush. The wire brushing left areas of bright metal which is not ideal for the feronite primer as it needs some surface rust to react and bind to, so I brushed on some hydrogen peroxide to promote surface rust blooming. The next morning I hosed the whole keel down with a pressure washer.
www.23hq.com/Jeanneau/photo/38992382/original3. Apply Feronite primer. This turns dark brown/ black after it reacts with the rust.
4. 2 coats of the Bote Cote epoxy were then applied as per instructions.
5. The next day I brushed out the rust pockets with acetone (styrene would be better) and filled all the holes with epoxy paste that you mix as per instructions. After this cured hard overnight, I sanded the whole keel to remove any high spots and was left with a reasonably smooth surface. I then applied another 2 coats of Bote coat making 4 coats in total and fared this off again ready for the usual primer and anti-foul.
Previously there were rust spots starting to appear within a month but this time there is nothing at all after diving on it 2 months later. I will monitor next year and update this post with the performance.
