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Discussion Starter · #1 ·
As promised on another thread somewhere, here are some pictures of my keel grinding on our Beneteau 50.

Warning this is very picture heavy. Don't use the "Quote" button, use "Post Quick Reply".

Here is a long sequence of pictures. I'll let them do most of the talking. Note that there was a lot of grinding -- from start to finish that day, about 2 hours worth, with a 4.5 inch Makita grinder. (Hint - use older/worn grinding wheels that have a smaller diameter for grinding out hard to reach areas.) I begin the pictures after I've removed the paint and previous barrier coat, and after a night with exposed metal. (After several hours of grinding the day before, I had to leave quickly to get 2 stitches in my knuckle.)

Throughout the day, I used a wire brush on a reversible drill to clear everything away and show me where there was still rust spots. Then I went after the rust with the grinder. I repeated that many times. In one place the night before, I found a "fault" which was 1/8 or 1/4 inch below the surface. I felt I needed to grind to smooth. The fault would certainly make a path for future rust to follow.

Somehow, I felt like a dentist. Now there's a scary thought.

Since these pictures, (this past Sunday) I did a full day of grinding under the keel, aft of the wooden block. That's with about 6 inches of clearance. I was tucked right up with my (very protected) face next to the keel, so I could see what I was doing. Driving home that night I counted my blessings that I didn't get seriously hurt. I only got a nick through my new leather gloves, and something under both contact lenses. THAT GRINDER TRULY SCARES THE CRAP OUT OF ME. I'm really not looking forward to about 5 more days of grinding, most of them under the keel. That's what I think I have left.

By the way, there are 2 rusty spots where the keel meets the hull (fore and aft). I have no idea how to do those.

Anyway, enjoy the pictures. Any feedback welcome.




















































































This is very picture heavy. Don't use the "Quote" button, use "Post Quick Reply".
 

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Sure would be nice if manufacturers would give up on iron keels. What a pain. I have one on my Dehler 39 which has rust spots. Boat is on the hard right now, boat yard said they could fix spots but no guarantee that they or their cousins would not appear next year, proper prep and barrier coat would help but no guarantee.

So I chickened out for this year, scrape, sand a bit, paint and go sailing. Next year I will likely be the one cursing, grinding iron for days.

Marvelous pictures, you are an inspiration. Hope your body survives the ordeal.

michael
 

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Discussion Starter · #5 ·
Not 100% sure that I'm doing it right. It feels like I'm grinding way to much. (I have taken off more keel than rust has done.)

SERIOUSLY... AM I GRINDING TOO MUCH???

.

As for underneath, it's really hard to get at all of it. A small (250 watt) worklight works, because it fits right underneath (not the 500 watt in these pictures). Light is everything here. I may also invest in a mirror. I do use my digital camera underneath, in movie mode. I slowly move the camera while calling out the position of the camera (how many inches from the wood block). The I sit and look at it to see where the rust spots still are.

Underneath gets harder because the keel widens as you go aft. For instance, 2 feet wide, with 6 inches of clearance to work with. You have to really get under there to get the rust out. After 6 hours of that, holding that tiger of a grinder, my arms get really tired. I'm planning on doing it in shorter sessions. The grinder requires continuous attention and finger strength. It's not something you want to do when tired.
 

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Discussion Starter · #6 ·
Great work Bene. I can see that whack on your finger too. What's the white stuff?
Thanks smack.

Zinc Oxide, I had a big tube of it left over from my lifeguarding days. (grin)

It's Interlux 2000e in white.
 

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Yep, the fear of this project was the major factor that tipped the scales from Bene to Catalina for me. Given the vintage boats in my price range, I knew I'd be facing this sooner rather than later, so Catalina's got the nod. The two brands share a lot of basic construction methods in common and there are several features Benes offer that I really like, but this is one onerous task I know I won't have to deal with.
 

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Boy, what an ugly, nasty task.

The first thing I'd do is check if the marina would hang the boat in the travelift straps somewhere in the yard and let a sandblast contractor come in and blast the bottom of the keel clean. (You're going to have to pay for the travelift to move your blocking, anyway.)

(Edit: The second thing I'd do is check for a yard that would allow sandblasting the keel if my current yard said no.)

Failing that, I'd rent or buy a 7" grinder, then have the boat hung overnight in the travelift straps with the keel bottom about waist high. Then sit in a lawn chair in such a way that my elbow would be on the armrest while supporting the grinder. This would be awkward, but it would keep you from having to support most of that tool weight while working.

Keep the wheel guard between you and the wheel.

From the amount of material you're removing, it looks like the iron is pretty porous (cheap casting) and punky from rust. If you can seal up the bad stuff and keep water out it should be OK if left on. The question is how well you can seal it up, especially on the bottom where it's going to be abraded when grounding.

One idea would be to leave the deep pits, then when you do the repair, add some layers of fiberglass, or even kevlar, cloth to the epoxy to protect against abrasion better.

If that eventually fails, you'll need to go back in and grind everything out, but if it holds OK, you'll save a lot of awkward grinding now.

Good luck,

Tim
 

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I think you are taking too much metal off. Just have it sandblasted, grind out any pits and then fair it with an epoxy filler (putty made with chopped glass and silica). Don't follow the cracks with the grinder; it won't make much difference in the strength or life of the keel if the rust is in there (it's like surface cracks in a sidewalk).

It's possible that if you use a zinc fish attached to a keel bolt when moored it will help minimize the corrosion of the keel if it has been exposed by flaking paint or scraped on the bottom. That's if your keel is not bonded to a zinc on the hull already.
 

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personally i would use lots of phosphoric acid to eat the rust off. it also gives the iron a iron phosphate coating with helps protect from rust, and holds paint very well. i know acid works well on things not in the water, i dont know how it would work for an iron keel thou. why is there no zinc on your keel?
 

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Discussion Starter · #12 ·
I get the feeling that I'm doing it the hard way, trying to save a few bucks and not hire a sling, the marina, a sandblaster....

The advice is much appreciated!!
 

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Rust converter from an automotive paint supply store.
Wire brush all the paint and loose rust and just paint it on.

I think it is phosphoric acid.

Cost less than $20 a quart.

follow the direction on the bottle.
 

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Maybe I'm wrong, but wouldn't a zinc stop least noble metal from dissolving while not doing much to stop rust which is a result of water and oxygen being present?
Brian
 

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When iron converts to rust it gives up electrons LEO. This means that if you have some really generous metal, say zinc, it should theoretically keep the iron in good shape by donating lots of electrons GER!

LEO GER!
 

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Discussion Starter · #16 ·
Could it be this simple???

Rust converter from an automotive paint supply store.
Wire brush all the paint and loose rust and just paint it on.

I think it is phosphoric acid.

Cost less than $20 a quart.

follow the direction on the bottle.
Could it be this simple???

.
 

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Could it be this simple???

.
No, phosphoric acid is a organic compound meaning it is water soluble. It is simply liquid Naval Jelly. It turns rust to iron phosphate. Bottom paint is not water proof. Barrier coat is. But to get barrier coat to stick the best you need to apply to shinny metal.

If you would just paint over phosphoric acid, the problem is once you splash the boat and it gets wet you lose the protection.
 

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Discussion Starter · #18 ·
Thanks Bubb2. That helps a good deal.

Not sure I mentioned it above, but I'm planning to do this in small patches. It will mean more trips to the boat, but don't we all need that anyway?
 

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I just meant that it was easier to deal with the rust.

You still have all the steps to protect the metal that you normally would do.:rolleyes:

No, phosphoric acid is a organic compound meaning it is water soluble. It is simply liquid Naval Jelly. It turns rust to iron phosphate. Bottom paint is not water proof. Barrier coat is. But to get barrier coat to stick the best you need to apply to shinny metal.

If you would just paint over phosphoric acid, the problem is once you splash the boat and it gets wet you lose the protection.
 

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Discussion Starter · #20 ·
So I can use the phosphoric as a "wash" to get all the rust out, and then apply barrier coat etc.?

Quesiton -- does the water in the "wash" casue rust (or flash rust onthe surface), or will it be good to go once the liquid dries.

...seriously considering this approach!
 
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