I'm fiddin' to haul my H34 for a bottom job. (I'm doing it) and I want to grind the keel down to bare metal and fill in all the pits and smooth it out and paint it, etc. So, I guess I need a primer to put on the bare metal, a filler to smooth over and fill in the pits and then the bottom paint. Is that it? What else? What are the best products, procedures for this? I know this has been discussed before. Thanks for your help.
Iron Keel prepping and fairing and painting
- Thread starter markwbird
- Start date
Depends on the keel metal. “Grinding” would not be my method, you paid good money for that metal! 
If it is iron you have a big job ahead of you and any shortcut you take will most certainly mean you will be doing it again. Pettit and Interlux both have lots of guidance on their websites and you would be best served by educating yourself. Don’t forget to search in the professional application support guidance.
If it is iron you have a big job ahead of you and any shortcut you take will most certainly mean you will be doing it again. Pettit and Interlux both have lots of guidance on their websites and you would be best served by educating yourself. Don’t forget to search in the professional application support guidance.
Grinding really doesn't work well. You need it blasted. Then you will have to begin the sealing process immediately after, before it starts to oxidize.
Grinding won't work. Surface is too irregular. Wire brush or some type of blasting will be needed. Zinc Chromate makes a good primer.
For my 23 keel I did some grinding with an angle grinder to get off the cruddy paint, lightly to not go deep. Then I used a coarse wire brush in the angle grinder. Sand blasting would have been better, as the wire brush can't scrape off 100% of the rust, but I didn't have access to a service.
Unfortunately sand blasting is not an option. It is not allow at the yard I am using. So I guess a good wire brush is in order. What about a very course sand paper?
I don't think anything short of an angle grinder will do much. I first tried wire brushes on an electric drill as I did not have an angle grinder. It would have been extremely slow. I can't see sandpaper even in an electric sander doing much, let alone by hand. If you use an angle grinder you can buy a sanding pad for disc sandpaper that may work in some places, but I think you will need at least a wire brush and maybe grinding/cutting disc too.
I had mine done 5 years ago, I contracted a guy who did it with that needle scalier device . It worked well but took quite a bit of time- it was only an inch or so dia. Not an expensive device.
I coated with a rust proofing liquid immediately then Interlux 2000 one coat, then filled with fairing compound, then 5 more coats of Interlux 2000. It has lasted well, I get one or two very little rust blips that come to the surface over the winter ( on the hard) This year there is one little dip about 1.5 inches that I will fair. The little ones I grind a small dimple with a Dremel the fairing compound the cover with VC17
I coated with a rust proofing liquid immediately then Interlux 2000 one coat, then filled with fairing compound, then 5 more coats of Interlux 2000. It has lasted well, I get one or two very little rust blips that come to the surface over the winter ( on the hard) This year there is one little dip about 1.5 inches that I will fair. The little ones I grind a small dimple with a Dremel the fairing compound the cover with VC17
ospho rust converter or por metal prep , then por15 ,then 4 coats of interlux 2000e ,I kept going just 2000e and kept having rust spots come thru. Read of someone going this method going 8 years no rust, I've gone 1 year now no rust, also add 2 anodes to keel.
Mark,
We did exactly as Richard Bryer did after exposing the bare metal. The rustproofing is important as it pickles the surface with a phosphate coating. It's called Ospho by Skyco. If you are going to BMC, they have it there. We only did some local patch repairs. The original coating was delaminated from the iron so it would peel off pretty easily. Maybe because water had gotten behind it already. In fact it was hard to get back far enough where it was well adhered to the iron again. At first we thought we were going to end up stripping the entire thing. This was especially true when I used a wire cup on my angle grinder to feather back the old bottom paint. As it heated up the original coating it would delaminate.
In our case, after chemical treatment, we rolled on a coat of West System epoxy and applied two layers of glass cloth tying back over the bare original coating. This was especially good to do at the classic Hunter Smile spot. After that cured enough to still be tacky we followed with three coats Interlux 2000 as Richard did but didn't follow up with any additional fairing. In our case it was more to prevent the crack at the hull to keel junction for about 6-7 years before having to repeat with the glass layup. At least on the repeat treatments we didn't go down to the bare metal as much, just at the crack and lay on some new glass/epoxy/Interlux.
We did exactly as Richard Bryer did after exposing the bare metal. The rustproofing is important as it pickles the surface with a phosphate coating. It's called Ospho by Skyco. If you are going to BMC, they have it there. We only did some local patch repairs. The original coating was delaminated from the iron so it would peel off pretty easily. Maybe because water had gotten behind it already. In fact it was hard to get back far enough where it was well adhered to the iron again. At first we thought we were going to end up stripping the entire thing. This was especially true when I used a wire cup on my angle grinder to feather back the old bottom paint. As it heated up the original coating it would delaminate.
In our case, after chemical treatment, we rolled on a coat of West System epoxy and applied two layers of glass cloth tying back over the bare original coating. This was especially good to do at the classic Hunter Smile spot. After that cured enough to still be tacky we followed with three coats Interlux 2000 as Richard did but didn't follow up with any additional fairing. In our case it was more to prevent the crack at the hull to keel junction for about 6-7 years before having to repeat with the glass layup. At least on the repeat treatments we didn't go down to the bare metal as much, just at the crack and lay on some new glass/epoxy/Interlux.
If you remove the barrier coat from the keel to bare metal plan on 5 coats of epoxy barrier coating followed by antifouling paint. That is what the boatyard advised me when the haul out during the survey showed the keel lost its barrier coat. Keel had to be sanded, followed by 5 coats of epoxy barrier coating then 2 coats of antifouling paint.
I have an iron keel on my Yamaha
Unless you have serious rust incursion, don’t grind/sand/ blast.
Treat the keel chemically (converter), fair, then epoxy.
You do not need to slather the epoxy on in a thick sheet, as the WFT is in mils.
You do not need a billion coats of every crazy gypsy concoction on the market; you just need to convert the rust, and then make a barrier to prevent further rusting.
Finish as you would normally.
The process needs redoing from time to time.
I haven’t had a problem yet.
Unless you have serious rust incursion, don’t grind/sand/ blast.
Treat the keel chemically (converter), fair, then epoxy.
You do not need to slather the epoxy on in a thick sheet, as the WFT is in mils.
You do not need a billion coats of every crazy gypsy concoction on the market; you just need to convert the rust, and then make a barrier to prevent further rusting.
Finish as you would normally.
The process needs redoing from time to time.
I haven’t had a problem yet.
I have used Interlux Primocon as a primer on the iron keel of my H.28.5. Worked very nicely prior to applying an ablative bottom paint.
Advise if keel is either cast iron or lead. If in doubt ask others but provide year of boat and if you want to call Mars Metals who cast the keel, they are in Canada
If cast iron, immediately coat with a metal primer that has zinc chromate in it. Fill in with two part epoxy and I use to use WaterTite but was one of the better ones. then barrier coats and bottom paint. Check with the local yard what is best suited in your area for bottom paint.
If cast iron, immediately coat with a metal primer that has zinc chromate in it. Fill in with two part epoxy and I use to use WaterTite but was one of the better ones. then barrier coats and bottom paint. Check with the local yard what is best suited in your area for bottom paint.
The original owners of my boat did the West System epoxy over the entire iron keel and faired in 2009. It has held up really well. I've repaired a couple of small spots in the past couple years. I used an angle grinder on the repairs.
JerryA
JerryA
I have an '84 Hunter 31 with an external iron keel. I cleaned the entire keel in several hours with a wire wheel in a die grinder, then primed with barrier coat, faired, three more coats of barrier coat and three coats of bottom paint. Six years later, still looks great. I don't remember what products I used, but they're sold by WM.
on both my boats, both having cast iron keels, the best thing I've found, after getting the keel clean , is coal tar epoxy. That's used on offshore rigs, buoys, etc. Stinks but sure holds up. After that cures, I use Interlux Interprotect 2000E, several coats. have had no problems with rust on the keels in years
The only thing I suggest over what has been written above is to apply faring compound after to paint the water barrier coat on. Then sand smooth and add more epoxy and then antifouling. Faring right over the metal itself usually ends up with failure.