Steel Keel Pitting- fill or paint over? (time sensitive question)

[bonkle]

I'm researching but need an answer asap as it's at the yard right now. There's 2 pics of the raw steel after first round of blasting and sanding and 1 pic after one primer coat to seal it up. Should I have them "skim it with West system" (quoted from text they sent) to fill the voids or just bottom paint as is? It seems like filling would just be cosmetic... maybe a negligible drag reduction.

 

[Don S/V ILLusion]

Depends on how often you want to repeat this. Skimming to fill existing voids won’t last long and certainly won’t protect the remainder of the keel.

 

[bonkle]

I'm guessing the boat has been neglected and water got under the bottom paint causing the pitting. Isn't it the paint that protects the keel?

 

[kloudie1]

Keel is cast iron. it needs protection and probably should be blasted and coated with something like an epoxy barrier coat or coal tar epoxy, then bottom paint. Regular bottom paint will not protect it. It won't get much worse in a year or two so ya may want to use a rust converter as a primer then get all stuff together for next out of water experience..

 

[bonkle]

Keel is cast iron. it needs protection and probably should be blasted and coated with something like an epoxy barrier coat or coal tar epoxy, then bottom paint. Regular bottom paint will not protect it. It won't get much worse in a year or two so ya may want to use a rust converter as a primer then get all stuff together for next out of water experience..

It's getting two more epoxy primer coats then bottom paint. Just wondering if any aditional "hole filling" is beneficial. I'm leaning toward no.

 

[dmax]

Your boat will definitely sail better with a faired keel - that's pretty rough, I'm pretty sure you would notice the difference if you could compare faired vs. not faired. I would do it now while you just have epoxy on there.

 

[bonkle]

I told them to do it... Now it won't be ready for yet another weekend

It looks like the two negative factors are losing a kt or more and being much harder to keep clean. The yard said it is mainly cosmetic, but I didn't want to make an uneducated decision. I figure it could never get properly cleaned with all those cavities and I figure that alone is reason enough to have it done.

 

[BigEasy]

Keel should be blasted to bright / shiny metal and coated immediately (same day) with multiple coats of Interlux barrier epoxy (2000).
Epoxy filler can be placed before final coat of barrier epoxy and faired to a smooth surface. After final coat of epoxy barrier, apply a couple coats of ant-fouling paint. Curious as to the "primer" that was applied after blasting.

 

[bonkle]

Keel should be blasted to bright / shiny metal and coated immediately (same day) with multiple coats of Interlux barrier epoxy (2000).
Epoxy filler can be placed before final coat of barrier epoxy and faired to a smooth surface. After final coat of epoxy barrier, apply a couple coats of ant-fouling paint. Curious as to the "primer" that was applied after blasting.

They use interlux 2000 epoxy primer and SeaHawk Cukote antifoul. The Interlux is what I mean by primer. They are doing 3 coats Interlux and 2 coats Cukote. There was another round of blasting and sanding after that first pic before they did the first coat.

 

[BigEasy]

They use interlux 2000 epoxy primer and SeaHawk Cukote antifoul. The Interlux is what I mean by primer. They are doing 3 coats Interlux and 2 coats Cukote. There was another round of blasting and sanding after that first pic before they did the first coat.

Good deal! I usually use apply some epoxy filler in areas where severe pitting has occurred (after initial coats of interlux 2000),
mainly for cosmetics in my case. Guess it is debatable if the filler is really necessary. Main thing is getting rid of the rust and sealing the keel to prevent further rusting.

 

[RitSim]

Blasting is best, but I had a cast iron keel on a Pearson 26. I used a needle scaler (Harbor Freight}. The needles get into the hoes and divots. I would never use a disk sander on your condition keel. It's been a few years, but I think I washed with Naval Jelly followed quickly by two part Primer ( Pettit E4700 ) gray first and 3rd coat and white for 2nd and 4th (i think four coats). Then faired and recoated one or two coats with the E4700. Bottom paint after that- no rust for years

 

[Daveinet]

On my cast iron keel, I sandblasted and then took a couple of rattle cans of zinc paint. I was going to paint over the zinc paint with a barrier layer, but never got around to it. 5 years later, it still looks pretty good. But this is a trailer sailer, so it didn't stay in the water.

 

[fstbttms]

I'm guessing the boat has been neglected and water got under the bottom paint causing the pitting. Isn't it the paint that protects the keel?

Anti fouling paint isn't waterproof nor is it intended to be. In fact, it works because water can penetrate it, thereby releasing its biocide.

 

[anelso29]

Hi OP,

I also have a Cast Iron Keel on my 84 Huntre 31, and I have some of the same issues. Here is what I did.

1.) To fix the pitting (only if you want to do this, it does not affect your sailing experience)
Use any type of Bondo Metal Reinforced Filler to fill in the holes and smooth the keel down.

2.) Prime your Keel for Paint
Cover your Keel with a primer that contains zinc chromate

3.)Protect your Keel against Further Rust
Cover your keel in a minimum of two layers of Interlux 2000

4.) Paint with your favorite bottom paint!

This may be more than what you are asking, but I wanted to share some of the knowledge that I have gained from this fantastic forum. I hope this helps!

 

[bonkle]

This expands a bit outside the thread topic, but I visited today and have questions. I may not be savvy with bottom paint, but I know some stuff about regular paint and I’m worried. There’s bubbles, leaking bubbles, unpainted portions (including bottom of keel sitting on blocks) and leaking rust. Thoughts?

 

[dmax]

Those look like blisters, water between the gel coat and the fiberglass layup. Reasonably easy to fix: https://www.westsystem.com/wp-content/uploads/Gelcoat-Blisters-Diagnosis-Repair-and-Prevention.pdf

The rust looks like water is getting in your hull-to-keel joint. You want to take a good look at your keel bolts (re-torque them too) and make sure they are sound. At a minimum, you want to scrape out as much of the joint as you can and re-fill with 3M 5200 or something like that.

Lots of info on both these subjects available.

 

[Davidasailor26]

The unpainted spots under the blocks are no big deal. It’s common to leave those and sometimes just touch them up quickly after the boat is lifted. Dry time before launching won’t be manufacturer’s specs but it’s still done.

The bubbles are a little more concerning. I agree with dmax that they look like blisters, but it would’ve been better to know about them before the fresh paint than now. The right way to fix them is to remove the paint and delaminated gelcoat down to solid laminate. They don’t look that small so it might be necessary to add some fiberglass back depending on how deep they are. Then fair, barrier coat, and paint.

I’m not sure about the rust spots on the keel. Since the keel was just recoated I’d hope that’s not already coming through from the keel itself. Assuming that’s the case then dmax is probably right about the keel hull joint needing to be checked and resealed too.

 

[bonkle]

Another forum mentioned osmotic blisters. I’ll inquire of all this, focusing on the keel bolts and seal. I the inspected and retorqued so I’m not worried about losing it. Maybe I can get a credit of sorts for the next visit. With this bill I better. The money hole in the water jokes are no exaggeration!

 

[jssailem]

Those protruding bubbles on the hull, you are pressing and they ooze a vinegar smelling liquid are osmotic blisters.
Those will not go away. They will get worse. Think wet feet, wet socks, bad fitting boots and 5 miles still to go on your hike home worse.
Here are a couple of data sources on this topic.

https://stevedmarineconsulting.com/wp-content/uploads/2014/03/Blistology-Pt-1-PMM-Jul_Aug-06.pdf

https://stevedmarineconsulting.com/wp-content/uploads/2022/03/Blistology-Pt-2-PMM-Jul_Aug-06-pages-deleted.pdf

Hull Blisters: Know the Enemy - Practical Sailor

Since 1974, Practical Sailor’s independent testing has taken the guesswork out of boat and gear buying.

www.practical-sailor.com

Owners of older boat’s who keep them in the water face the problem. Some will spend lots of money trying to repair the damage, skimming the hull surface, drying the boat in the yard for years, resurfacing the hull with laminating glass, adding barrier coating and bottom paint. Some (count me in) with a thick hull will spend a little money popping, filling, barrier coating the more offensive of the pox.
My 50 year old hull has been on the hard for 58 days and counting. In that time the workers have sanded the bottom. Exposed numerous gelcoat blisters. Ground out and filled them, then covered them with a thickened epoxy, painted them with 2 coats of barrier coat. Now will add the bottom paint.


The weeping rust drips makes me suspicious, you have water in the deck joint. If water is seeping out it can seep in when you drop the boat into the water. I would want that resolved before splashing my boat

 

[JamesG161]

The preparation for full bottom paint.



Keel joint leaking is important.

Water leaks when out the water equals Water in when afloat.
Water in will eventually attack your keel bolts.

Jim...