Repairing Cast Iron Keel

[Bob Ford]

Fab a new one out of 1/4 - 1/2 plate. Two sides with a hollow center and the top open. In the hollow center pour Epoxy with lead shot for weight. Plates and edge could be Mild or stainless.

Bob

[HWooldridge]

Oy...braze it back together and get back to sailing. Another good method is to lay steel straps across the break then braze or weld (with cast iron specific electrodes).

[derekm]

My cast iron keel from a sailboat has broken. It is about 18"x72"x1.5". The break is across the 18" dimension and revealed a void in the casting. I have looked at building up a new keel from steel plate but the materials alone will hit $1000 even if I try and use what I can haul from the scrap metal yard.

I have gas and stick welding equipment. What I have read about welding cast talks about heating and allowing for a slow cool of the material. I can't imagine trying that with such a big mass of metal. There are some lower temperature brazing materials that will work at temps below 600. Anyone have experience with these? I am considering trying some sort of mechanical joining followed by that.

The casting is of very low quality. Lots of small voids. I removed it for other repairs to the boat and was going to fill the voids and repaint it while it was off.

Any suggestions greatly appreciated.

ArkTinkerer

I 'm assuming the keel joins on to boat along a 72" by 1.5" surface
get a 72" of 1" by 1.5" steel bar profile to match top 1" of joining surface of cast iron
machine 1" off the joining surface of cast iron. drill & CSK 1/2" holes through bar to mating tapped holes in cast iron every 6"
on bottom of the keel cast iron machine recess for a 3/8 by 3/4 steel strap for a much of the length as practible drill ck & tap 3/8" every 6".

This should help in case are there any more voids

[mark61]

Braze it.

Build a fire under it then when it is good and hot braze it then throw a little more wood on the fire. Let fire go out-if you can cover the keel with something to slow the cooling fine it not just drop it right into the ashes and keep it from getting rained on until it cools down.

mark61

[Weston Bye]

Its a swing keel...

Knowing that, I would now be concerned with just welding or brazing, lest the weld fail in deep water and you loose part of your keel. You might want to add strapping in addition to the weld so that if the weld fails you don't loose the broken off piece. The strapping might have to be thin or recessed into the keel so that the keel isn't too wide to fold up into the keel trunk in the hull.

[derekm]

You could join it using the epoxy grout method used in concrete

Drill and tap coarse thread holes in the broken faces.

Then epoxy with coarse undersize allthread bar spanning between the holes

metal loaded epoxy might be best.

[ArkTinkerer]

Its a swing keel so its not jointed along the 72" dimension--it pivots from a hole at one end.

Like the idea of the epoxy with metal but with a mobile part like this I'm not sure how it will hold up.

Gonna try welding a couple 8"-12" braces to the front/back edges maybe a side strap or two (lots of short welds to keep temp down) and then low temp braze the center (one of the 500-600 degree alloys so I guess I should say solder not braze). We'll see how it goes. Success or failure I'll try and get some pics and post the results. If I fail, then its time to pry open the wallet and buy some materials. Thanks for all the input!

[HWooldridge]

Good luck!

[TeamFCAR]

ArkTinkerer,

Is your vessel by chance a Venture 24 or McGregor 25? My Dad had the Venture where the swing keel was a 2"x4" steel beam from the pivot lock through the pivot point and embedded into a large Lead casting. Everything was then faired with fiber glass and gel coat. Later versions of the same boat had the had the entire swing keel made from cast iron. I can easily imagine the cause of your crack may have created the twist we found in our keel. In our boat it was pretty easy to drop the keel out of the pocket in the bottom of the hull onto the trailer, set the boat in the water with the boat crane and then using the crane to move the keel to the bed of the pickup. Once in the truck it was taken to a local shop to weld the holes and make new ones that were square to the lead bulb.

If your boat is similar I would separate the keel from the boat and find a local shop capable of such a large repair. Otherwise I would look for a donor boat.

Good Luck,

TeamFCAR

[derekm]

Its a swing keel so its not jointed along the 72" dimension--it pivots from a hole at one end.

Like the idea of the epoxy with metal but with a mobile part like this I'm not sure how it will hold up.

Gonna try welding a couple 8"-12" braces to the front/back edges maybe a side strap or two (lots of short welds to keep temp down) and then low temp braze the center (one of the 500-600 degree alloys so I guess I should say solder not braze). We'll see how it goes. Success or failure I'll try and get some pics and post the results. If I fail, then its time to pry open the wallet and buy some materials. Thanks for all the input!

now I get it... there a a lot of twisting forces on this.... make those straps wide and long 12"+(300+) wide 1/4"(6) deep and most of the length of the keel. lots of csk screws to tapped holes 5/16" (8mm) in the opposite plate, with slow setting epoxy between plates and cast iron. lot of machining for the strap recess