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Keel paint disappointment

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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Initially Posted - 12/29/2004 : 11:00:08

Keel paint disappointment ...
Many of you remember the extensive bottom job I had done last winter, I was very surprised to see the keel look like this after I hauled. The first picture I can sort of understand because of trunk wear, the others I don't get at all. I am especially confused because of the rust barrier coat I had put on under the keel. I am tempted to buy a can of rustoleum and just spray these spots. Do I really need to sand down to metal?

Edited by - on

Jeff McK
Captain

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USA
389 Posts

Response Posted - 12/29/2004 : 11:25:29

Frank,

The wear pattern in the last photo looks suspiciously like you've been plowing the lake bed.

Everything else looks like a combination of wear against the inside of the trunk or a failed primer coat.

I did not follow your bottom job efforts, so don't know what paint you used as the final layer. Since you are apparently in fresh water, I'd guess you are using a thin film paint like Interlux VC-17 or Petit SR 21 (feel free to correct my lack of knowledge). If so, did you put on more than one coat?

IMHO, you need to get the rust off first, then put on a new barrier coat. I don't know what you used, but maybe something else might be worth a try this time.

Best of luck, and wishes for a Happy New Year.

Edited by - Jeff McK on 12/29/2004 11:43:16

Charlie Vick
Captain

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USA
423 Posts

Response Posted - 12/29/2004 : 12:58:30

Off the subject but that sure is a sad looking signature pic Frank.
I hope you can get here back to the water soon!

Edited by - on

Steve Milby
Past Commodore

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USA
5932 Posts

Response Posted - 12/29/2004 : 13:17:08

Frank, I don't see any indication that there is a barrier coat on your keel. Believe it or not, most inland marinas around my neighborhood have never heard of barrier coat. If you tell them to apply a barrier coat before they put on the bottom paint, they would probably apply Rustoleum. I suggest you ask them what specific barrier coat they applied.

If all it has is Rustoleum or something similar, you can just sand the rough spots and paint over them. But, if I were you, and the marina didn't put a real barrier coat on the boat, I'd expect them to make a reasonable adjustment, such as prepping it properly and applying real barrier coat and only charging for the materials at the manufacturer's suggested retail price.

Edited by - on

Jeff McK
Captain

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USA
389 Posts

Response Posted - 12/29/2004 : 13:53:13

Steve,

I am not a paint pro, but wonder how well a thin film paint like Interlux VC-17 or Petit SR 21 will stick to Rustoleum since they typically have teflon in them. If the answer is "not too well" it sounds like there is a major clean-off & repaint in the offing.

Frank: You might want to look at Interlux 360R Underwater Metal Primer (found this in the WM catalog). $25/Qt, covers 50 Sq. Ft. Reportedly this works OK in fresh water, is anti-corrosive & is compatible with most bottom paints.

Edited by - Jeff McK on 12/29/2004 14:12:01

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 12/29/2004 : 16:59:03

Yowser... that's a freshwater boat? If the paint job didn't hold up in freshwater, you can imagine that in saltwater you would have cranked up a big slab of rust.

I'd disk sand a bit to get 'fair' and get rid of loose stuff.
Put some Ospho on followed by a few coats of Krylon galvanizing primer (the $5 a can stuff).
Follow that with a couple top coats of derusto followed by your bottom paint.
She should hold awhile in freshwater.

IMHO... the only thing that stands a chance of lasting awhile on an iron keel is full encapsulation in epoxy. (saltwater) Even that's not a forever thing.

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 12/29/2004 : 18:10:00

Recall that I had the bottom and keel soda blasted. I called the dealer today and he said that the soda blast was not good enough to prevent the rust and that he would not redo the keel for me. He said that on his racing 22 they removed the keel and had it sand blasted until it was shiny then faired and encapsulated it and that surely I did not want to do that. They suggested that I sail rusty.
At the time they thought the keel looked great and assured me that they would do a little sanding and filling to fair it a bit. They then remarked about how fast they needed to do all of this because the iron needed to be painted before it could begin to corrode. You can see the grey of the "rust-loc" barrier coat on the picture of the foot.

Edited by - Frank Hopper on 12/29/2004 18:12:35

Jeff McK
Captain

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USA
389 Posts

Response Posted - 12/29/2004 : 19:08:52

Frank,

Please understand I'm coming in late on this whole story, so absolutely no insult is intended to you or anyone in the forum who advised you through the original process.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">I called the dealer today and he said that the soda blast was not good enough to prevent the rust and that he would not redo the keel for me.<hr height="1" noshade id="quote"></blockquote id="quote"> Maybe I missed something in your message, and have no idea of the decision making process, but if he knew the soda blast wasn't going to be good enough, why did he do it?

It certainly is a shame the B@$+@&* won't stand behind his work.

Sail unpainted & rusty?? IMHO that is really terrible advice. Maybe an epoxy paint over a good anti-corrosion primer laid on sandblasted metal is the answer? It wouldn't be cheap, but...

I feel for ya, & hope you can get a good resolution.

Edited by - Jeff McK on 12/29/2004 19:17:36

Brooke Willson
Admiral

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USA
983 Posts

Response Posted - 12/29/2004 : 21:39:32

Frank, I'm following all this with great interest -- "Even Chance" is on the hard with a pitted and rusty keel. I've been reading several articles about fairing, painting, and otherwise coating swing keels. I don't have them at hand, but one I read said that encapsulation is highly questionable, because if that coating is violated, it causes far worse damage by hiding the rusting underneath. My keel is a work in process, and won't be attacked until March, but my yard seems to be leaning towards sanding, fairing with Marine-Tex or something similar, priming, and then painting. The bottom of your keel is proof why there's no permanent solution to having a cast iron keel in salt water.

I'm glad we have this forum to commiserate!

Brooke

Edited by - on

MattL
Admiral

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USA
990 Posts

Response Posted - 12/29/2004 : 22:43:44

When I took an autobody class a couple of years ago they were really stressing, I think it was an acid wash after grinding this puts a thin layer on to prevent rusting till the metal primer is applied. I did get a good grade in the class, but I was more intersted in working on the fiberglass of my corvett and didn't really commite the metal stuff to memory. Check with an auto paint store for the proper stuff to use.

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 12/30/2004 : 10:09:46

Having owned two cast iron swing keels kept in salt water for over five years each, I'm a strong believer in sandblasting followed by epoxy encapsulation. I can post a more detailed procedure if anybody's interested.

-- Leon Sisson

Edited by - on

aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 12/30/2004 : 11:44:30

Frank,

Just to add fuel to the fire, my wing keel started losing its fairing material four years ago. The metal beneith was rusting and probably caused the fairing degradation. To repair the damage I sanded and applied an anti-rusting compound to the metal. I don't remember the name but I found it at ACE Hardware. I then refaired, primed, and painted. I haven't had a recurrance since. In my opinion, the critical factors were doing something to prevent the metal from rusting and priming before painting.

Al
GALLIVANT #5801

Edited by - on

Steve Milby
Past Commodore

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USA
5932 Posts

Response Posted - 12/30/2004 : 12:38:41

You really only have two choices. You can do it the hard, expensive way, essentially as Leon suggests, or you can do it the easy way. If you do it correctly the hard way (applying a heavy epoxy barrier coat), you won't have to mess with it for awhile, so long as you don't hit something with it and break its seal. If you do it the easy way, you'll have a little sanding, filling and painting to do every year.

If you are in salt water, you should probably do it the hard way, although I'll defer to the judgment of the saltwater sailors on that question. I keep my boat in fresh water, and have prepped my boat both ways.

When I applied the barrier coat to my iron keel, I didn't have it sandblasted. I stripped off all the old bottom paint with chemical paint stripper, and washed the keel with acetone. Then I dug out any old, loose fairing material and used a wire brush in my drill to clean the pitted areas. (If you tap all over the keel with a hammer, you can hear a dead sound wherever the fairing material is loose.) Next, I sanded the keel smooth and immediately painted over any bare metal spots with a spray can of the primer paint that has acid in it and turns black after it dries. Then I filled the pits with epoxy filler specifically designed for use underwater, and sanded them smooth. Finally, I painted the keel with about five coats of barrier paint, and covered it all with teflon antifouling paint in accordance with the manufacturer's instructions. (The antifouling should be applied within a short time after the last barrier coat is applied.)

At the end of last season (the second season) it still looked very good.

By the way, I used to have to replace quite a bit of fairing material that blistered off my keel every year, and finally installed a zinc on my keel, and that seems to have cured that problem.

Sandblasting is good, but I think it can be done without sandblasting, if you are careful to prepare the surface properly.

Edited by - Steve Milby on 12/30/2004 12:46:07

thaind
Navigator

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Canada
145 Posts

Response Posted - 12/31/2004 : 09:00:08

I'd like to hear more about Leon's encapsulation method. I am in the same situation, wirh the Catalina smile on my fin keel. My situation is also different in that I am a Tech teacher, have the boat in my shop, and have ability to follow any chosen path with regard to equipment and time. My plan was to air chisel and sand blast keel until all bare areas are removed to clean metal, epoxy prime, fair with an epoxy filler compound, seal again with epoxy (Interlux 4000 series) and finaly bottom cote. I am not sure if it is desirable to seal before filling or not, but don't care how long it takes so long as it will be a lengthy fix. Boat is to be sailed in fresh water.

Open to any suggested changes/adittions to this approach.

#729

Derek Thain

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 12/31/2004 : 10:46:03

Derek,<blockquote id="quote">quote:<hr height="1" noshade id="quote">I'd like to hear more about Leon's encapsulation method.<hr height="1" noshade id="quote"></blockquote id="quote">Here's a rerun of a message I've posted before in response to a similar inquiry. I hope you find it helpful. Let us know if you have additional questions.

I've reconditioned two swing keels so far. The first was for a Venture 22, the most recent my 1979 Catalina 25. Here's what I did to them:

Forget grinding down the rust as a viable permanent solution. It's a waste of time and effort. There's no way to grind down into all the pits, and any remaining rust will spread like cancer. Sandblasting is what works. After removing the keel from boat, I had it sandblasted to "bright" metal. This is so not fun that I cheerfully paid someone else to do it even though I own a sandblaster and two compressors. At this point, the surface of the cast iron looked like silver grey moonscape or volcanic rock.

As soon as I got the keel back from blasting, I etched it with hydrochloric acid (a.k.a. industrial strength toilet bowl cleaner - be carefull!) to remove the rust remaining in tiny pores, and the rapidly occuring surface oxidation. I then rinsed it with lots of water, and treated it with two applications of phosphoric acid (a.k.a. "Ospho"). After that was thoroughly dry, I used a nylon scrub brush to remove any dusty residue. At this point, the surface of the cast iron looked like black or charcoal grey moonscape or volcanic rock with a bit of a shine to it in some areas.

Keep a garden hose handy when working with strong acids. Don't let acid spills remain on concrete that you care about. Don't wear clothes that you care about for any of this work. Wear appropriate personal protective equipment, don't run with scissors, etc.

Next, I applied two coats of WEST epoxy. At this point, the surface of the cast iron looked like honey glazed black moonscape.

Once the process of applying epoxy begins, try not to go more than 24 hours between coats so as to maintain a tight primary chemical bond between layers. If more time elapses, then wash with water, sand, and wash again with acetone before applying the next (delayed) coat.

Then I made up fairing putty from WEST with filler additives (WEST#407), and rough faired the keel. When I say "rough faired" here I mean the correct general shape, but with no special attention paid to tiny pits, scrapes, scratches or other minor imperfections in the surface finish. At this point, the surface of the keel looked sort of mottled, like camoflage paint applied by someone colorblind, or a rare skin disease.

After rough fairing, I wrapped the keel in two layers of 14oz. fiberglass cloth and WEST epoxy to protect it from misc. abrasion in the future. (If you skip this step, the barrier coat is much more easily breached by rough handling, crab traps where they don't belong, gentle groundings, or even brushing through enough shellfish clinging to weeds.) I also added a bronze shoe where the keel runs aground, and piled on several more layers of cloth and epoxy in that area, and along the leading edge. At this point, the surface of the keel had the texture of the woven fiberglass cloth.

After lightly sanding the fuzz, stubble, and frayed edges of the cloth, I did another round of final fairing on top of the fiberglass (WEST#410), followed by several last coats of epoxy resin as a barrier, and to protect the fairing compound from future bottom sanding. By this point, the keel surface was smooth, and almost perfectly fair except for a slight bulge where the bronze shoe was buried under glass.

I then applied copolymer bottom paint (which should minimize the need for future bottom sanding).

I also repaired the swing keel pivot hole at the same time by installing a bronze bushing, but that's probably not of much interest to you, as you have a fin keel.

Finally, I reinstalled the keel under the boat in my driveway.

If there can be a good side to all this work, it's that if you do it right, you don't have to do it again. This was done several years, and a few haulouts ago. I have carefully inspected the results each time the boat is out of the water (and each time I get around to diving under it). Most recently, I just finished routine bottom maintenance a couple of weeks ago. The same goes for the Venture 22 keel I did all this to. In both cases, the only visible damage to the encapulation occured where the keel had been run aground. The damage stops as soon as it reaches the bronze shoe.

Where the water tight integrity of the sheathing was breached, rust and the resulting delamination began to spread under the epoxy and fiberglass, but only very slowly (maybe an inch or less per year in saltwater). It is easy to sand back the paint, grind back the damaged fiberglass, clean up the light rust, and reapply the encapsulation, as described above. I can't over emphasize how much the bronze shoe reduces the need for this sort of touch up repair.

Good luck with whatever method you decide to use.

-- Leon Sisson

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 12/31/2004 : 11:21:38

Leon's got it described 100% right... and it's the only way an Iron keel will live in saltwater.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 12/31/2004 : 12:37:19

The acid-based primer that Steve Milby mentioned is sometimes called Rust Reformer. One version is made by Rustoleum--a milky liquid I bought in a plastic bottle. It's an alternative to getting every last speck of rust off, since that's pretty difficult to do. It actually dries clear on non-ferrous surfaces, but turns any ferrous material black (including your skin, which apparently has some iron in it) and leaves a clear coating on it.

In my saltwater environment, I've seen countless encapsulated iron keels where the encapsulation hasn't worked for long--one little whack and the game's over. And most of them were fixed keels. A keel that slides up into a trunk and then bangs around in it seems like a "lost cause" to me--it's going to get dinged. Face it--it's cast iron, and it will rust.

However, the worst that I've seen had probably lost less than .0001 of their mass over 20-30 years, so fairness would seem to be the only real issue. Some spot repairs (starting with rust reformer) can make it fair, and a zinc will reduce deep pitting. When the boat's in the water, nobody will see the little rust spots... When she's on the hard where your buddies can see the keel, just put a bag over it...

Edited by - on

Brooke Willson
Admiral

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USA
983 Posts

Response Posted - 12/31/2004 : 13:09:10

I'm with you, Dave. And maybe I should think about the wing conversion a few years down the road.

Brooke

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 12/31/2004 : 19:09:29

In my experience, allowing the top section of a swing keel to flake and 'expand' with rust will damage the keel trunk. On my V23 I had to repair deep scratches in the trunk area due to the rust volcanoes that had formed on the head of the keel.

After excapsulation and 8 years mostly in saltwater, the swing keel on my V23 was still looking pretty good when I sold her. That didn't mean she didn't need some maintenance along the way, but I didn't have to drop the keel out of the hull once it had been encapsulated.

Most of the dings and subesquent keel touch-up occured along the leading edge, which is pretty accessible. I've never had an issue with paint or other surface damage due to the keel banging around in the trunk.

I was disappointed in the performance of the rust reformer product by Rustoleum. (It's a water-based concoction of Oxalic acid). I went back to Ospho (phosphoric acid) and for small touch-ups I use a spray-can formulation by Permatex.

Just my 2 cts.

Edited by - on

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