Cast Iron Keel Repair

D

docschreiber

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Mar 29, 2015
6
Coronado 23 mkII Gulf Shores, Alabama
I have a '72 Coronado 23-2 that I recently purchased. My intention was to buy a "ready-to-sail" boat, but due to various circumstances that did not happen. I am a complete newbie to sailing and boat repair.

The keel (Iron, I think....) had multiple areas of rust showing, so I stripped it down to metal with an angle grinder and 80 grit sanding pad. On the starboard side I have found a large area (1 foot wide by 10 inches tall by ~5-7mm deep) area that someone had filled with Bondo and painted over. I have cleaned it out, and am searching for the best way to fix it right. Any help is greatly appreciated!

I've tried uploading pictures here, but keep getting upload errors on the photos. I've reviewed the guidelines and the pics should load, so if anyone can help here I'll get photos up. I put them on my facebook page and made them public, so anyone can view them there. Sorry for the extra step.
https://www.facebook.com/chris.schreiber.182
 
Sprega

Sprega

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Sep 12, 2012
115
O,day 27 Brownsville Marina
My last boat had a cast iron keel in similar condition. As I recall, I stripped it to bare metal, treated it with a product called "ospho" sealed it with epoxie, faired it with epoxie with thickener (don't remember what I thickened it with) put on a couple of more coats of epoxie and bottom paint. Still looked good when I sold the years later. Good luck and welcome to the wonderful world of sailing.
 
Phil Herring

Phil Herring

Alien
Mar 25, 1997
4,922
- - Bainbridge Island
Sorry about that, the photos were my fault. I was changing some server settings and caused the problem. Should be working now.
 
woodster

woodster

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Sep 15, 2009
6,243
S2 9.2a Fairhope Al
did those settings have anything to do with the gear adds.....when i click on something for sale i get a blank page and have been for 2 days now
 
SoSound

SoSound

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Nov 21, 2007
673
Beneteau Oceanis 34 Kingston, WA
Quite a project to start with!

Wow! Starting with a cast iron keel, you've tackled a big one right away, but you're on the right track! Hopefully, you'll get input from a couple of others who've done the same job.

One important item in the restoration process is to make sure that you seal it (the 'ospho' step?) right away when you get to bare metal. Don't let it set for a long time between reaching bare/clean metal and sealing it. Especially with the humidity in TN.

I let the folks in the boatyard tackle my cast iron keel (pretty much a necessity with our rules on collection and disposal of materials), and I was glad that I did!
They had to use a needle gun to remove the old paint and rust, then barrier coated with two coats of epoxy and then bottom paint.
 
agprice22

agprice22

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Aug 3, 2012
2,542
Performance Cruising Telstar 28 302 Watkins Glen
You can fill and fair that keel with West System 610 thickened epoxy; however, that is expensive. You can make your own with West System epoxy resin, slow hardener, and West 404 High Density Filler. The 404 is for underwater use. Mix the resin and filler, adding filler til you have a thick paste, a little thicker than you want. Then add the right amount of harder and mix that in. Then fill and fair the damage / voids in the keel.

Mix it in a wide Tupperware container to make it easier to mix and to keep it from kicking.

I would use a thinner mix on the rest of the keel to make it easier to spread and get an even coat.

Use the West System pumps to get an exact ratio.

After the epoxy residue hardens in the pan, just flex the pan a little to break it out.

Thanks,

Andrew
 
C

Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Cast iron can be welded as well. Maybe one of our welders will come on and explain the process as I am at least aware that it is a precise concept to get it right. Preheat the cast iron? Chief
 
woodster

woodster

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Sep 15, 2009
6,243
S2 9.2a Fairhope Al
actually chief it can be welded ......but it is a bear to do..... yes preheating is one thing that has to be done and after welding it ...it may have to be cooled down slow and controlled as in cooling it down in temp drops ...most of them are made of very low grade materials or have a lot of surface rust scale in some cases it may be better to have a new one made from a casting company...there are a lot variables in this process...but from his description i would not worry about welding it just fill it with a good grade epoxy filler and fair it out and go on
 
C

Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Woody: I figured you might address the welding prospect. Thanks for giving us more detail on that. Chief
 
Jackdaw

Jackdaw

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Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Agprice and Sprega called it,

Strip to bare metal
Treat surface
Barrier coat
Epoxy fill
Barrier coat
Paint

Welding would be a disaster even if you could figure out a way to do it. You want SMOOTH surface.

The Ospor step chemically changes any surface rust to an inert substance, ready to be barrier coated. So no rush.
 
woodster

woodster

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Sep 15, 2009
6,243
S2 9.2a Fairhope Al
Jackdaw said:
Agprice and Sprega called it,

Strip to bare metal
Treat surface
Barrier coat
Epoxy fill
Barrier coat
Paint

Welding would be a disaster even if you could figure out a way to do it. You want SMOOTH surface.

The Ospor step chemically changes any surface rust to an inert substance, ready to be barrier coated. So no rush.
Click to expand
exactly...a big bingo jack
 
C

Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
I wasn't suggesting welding. I was just curious as to viability and sailing safety and if welding would be better in this case. I got the answer from you two and that was my objective; for clarification for all of us. Thanks, Chief
 
Tsatzsue

Tsatzsue

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May 16, 2011
555
Macgregor V-25 Charlton, MA- Trailer
I pulled the keel and ground the rust off. I the wire wheeled it. The next step or actually three steps was the POR15 process. Degrease and then etch with the recommended products. Got everything from Eastwood. I then top coated the whole thing with Rustoleum industrial gray. Worked mint.

Second time BTW. First time was all the prep work and a rust converter before Rustoleum primer and paint. POR is bulletproof. Touch up where you hit rocks.

Yes the Ocean is shallow. Who knew!!

Happy Sailing!!
Ken B
CMDRE
North East Trailer Sailors
 
Sprega

Sprega

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Sep 12, 2012
115
O,day 27 Brownsville Marina
Jackdaw is right about the ospho. Also, I have had EXCELLENT results with epoxie from US Composites. Way cheaper than west.
 
rgranger

rgranger

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Jan 19, 2010
12,553
Hobie 16 & Rhodes 22 Skeeter Charleston
Sprega said:
Jackdaw is right about the ospho. Also, I have had EXCELLENT results with epoxie from US Composites. Way cheaper than west.
Click to expand
Yeah

I don't think you have lost enough ballast for it to make a difference. If you are worried about it, you can add let shot to your thickened epoxy but I really don't think it is worth the trouble.
 
D

docschreiber

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Mar 29, 2015
6
Coronado 23 mkII Gulf Shores, Alabama
Thanks to all for the quick replies. I'll be getting supplies lined up this weekend and giving it a go. This will be my first time working with the epoxy, so I'll probably try a small test batch or two before going for the big project.
Long story short, I didn't know enough when I bought the boat and was "misguided" by the person I bought it from in regards to the boat's condition. I also have a slightly OCD condition where I can't do a project halfway :). Goal is to get the bottom done in the next few weeks and be in the water by July. Ambitious but reachable I hope!
 
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