Recommend A Bottom Paint for my partially repaired swing keel? (current keel paint unknown)

[Carl Wonderful]

Hello,

I cant seem to get a good answer for my issue as its a little complicated. Need a good final (bottom coat?) paint to finish the keel. 1971 Cataina 22 swing keel. Old owner passed years ago so I have not idea what kind paint he used on the keel... but also don't want to re-do the entire keel as 80% of it is fine... 20% of the top is rusted.

Will be on a a freshwater lake in PA for 7 months out of the year. I don't race and this is the hard part of the keel to get to, so I'd like to not have to take my keel the whole way off every year to repaint it.

Also does this process sound like a good plan.. I will be doing as soon as I know what bottom paint to get. I already have all the products which I mention so this is what I'll be using for everything, except the final bottom coat which I dont know what to get for that.


The process....

1. Hammer, scrape and grind all rust parts down to shiny metal. then immediatly....
2. Clean with total boat dewaxer and surfice prep.
3. Apply total boat rust primer...
3a. clean and/or sand before next step?
4. Apply 1 coat totalboat Totalprotect Epoxy Primer
4a. clean and/or sand again before next step???
5. Apply Totalboat Total fair to fill holes and make all smooth.
5a. clean and/or sand again???
6. 3 more coats of totalboat Total protect expoy primer
6a. clean and/or sand again???
7. Then a final coat. Whats a good solid final coat option and how do I prep for it?



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[pertaining to the 80% that is already painted with some layers of unknown paint, but is in good shape...

Do I just do this whole process to the rusted parts maintly, but sand a few inches into the old paint and just feather everything I do into these couple inches to make the transition...
OR do I just like, clean the old 80% of the keel real good and sand it with 80 grit and start at #4 by goign into/over the old (unknown) paint with the totalprotect epoxy primer and keep covering the whole keel like that from then on? ]
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-So is my plan and products good?
-How often do I need to clean, sand, or both in between steps?
-Whats a good simple and solid final bottom paint for the keel of a freshwater boat docked 7 months of year?
-And how do I transition into the old, good, painted areas.... or do I just cover over entire keel starting at the totalprotect epoxy primer step?

Thanks guys (and gals)

 

[thinwater]

With that much pitting I would really suggest sand blasting. It is impossible to get into the pits with any practical sanding and grinding process, and a rust converter is a poor substitute.

If you can find someone to take it to it might not be very expensive. Or wait until someone is blasting at your marina.

---

If that is impossible, get a small needle scaler and really work the pits over. They are cheap at places like Amazon and Harbor Freight.You will need a good sized air compressor as well; check the CFM requirement. Not huge, but not a tire inflator.

 

[Carl Wonderful]

Can anyone help me out with recommendations on a final (bottom) coat?
Also if my process is good enough to start working on it?.... Or if not what you would do differently as far as the steps and the order?

 

[Tally Ho]

I would also recommend blasting all of the old stuff off (grinding/sanding may be ok) to get the keel as clean as you can.

Fair it (but be careful with adding much thickness in the area that appears to be scraping in the trunk).

I have used various epoxy barrier coats and I think for this job, most any 2-part epoxy barrier coat will work, including Total Boat.

For a final coat ( I assume you mean an anti-fouling paint), always good to find out what others in your waters use. Iam on Lake Michigan, and VC17 is a common bottom paint for our fresh water sailing. Goes on very thin, can last maybe a few years, but it does need to be refreshed every other year or so generally (many people reapply annually).

The good news is there isn’t a lot of prep needed. Wipe it down and apply a new coat. It doesn’t build much volume, so your keel won’t “put on weight“ and start getting too fat for the trunk.

Greg

 

[Carl Wonderful]

I would also recommend blasting all of the old stuff off (grinding/sanding may be ok) to get the keel as clean as you can.

Fair it (but be careful with adding much thickness in the area that appears to be scraping in the trunk).

I have used various epoxy barrier coats and I think for this job, most any 2-part epoxy barrier coat will work, including Total Boat.

For a final coat ( I assume you mean an anti-fouling paint), always good to find out what others in your waters use. Iam on Lake Michigan, and VC17 is a common bottom paint for our fresh water sailing. Goes on very thin, can last maybe a few years, but it does need to be refreshed every other year or so generally (many people reapply annually).

The good news is there isn’t a lot of prep needed. Wipe it down and apply a new coat. It doesn’t build much volume, so your keel won’t “put on weight“ and start getting too fat for the trunk.

Greg

Thanks for the recommendations. I Have heard of a lot of VC17 users. And yes I actaully just grinded al lthe rust away...Lots of shiny metal now.

So do people really raise their boat off their trailer and take the entire swing keel off every year or 2 years? That seems a bit much to me. I can see doing the whole thing and taking the keel off every 3 or 4 years to re coat and to maybe replace the 4 bolts that hold it to the hangers just to be safe and keep them from breaking inside there (they're cheap).

Also I worry about what kind of paint the original owner used and how my new application will transition into the old unknown paint..? (what if its not compatible..)

 

[Tally Ho]

So do people really raise their boat off their trailer and take the entire swing keel off every year or 2 years? That seems a bit much to me. I can see doing the whole thing and taking the keel off every 3 or 4 years to re coat and to maybe replace the 4 bolts that hold it to the hangers just to be safe and keep them from breaking inside there (they're cheap).

I don’t know about swing keels. Most of the boats I see are fixed keels. But yes, figuring out a way to lower the keel while on the trailer would be helpful…even if you can’t get the whole keel painted.

Also I worry about what kind of paint the original owner used and how my new application will transition into the old unknown paint..? (what if its not compatible..)

That is why we recommend blasting it or grinding/sanding off ALL of the old paint.

Greg

 

[Captain Larry-DH]

Thanks for the recommendations. I Have heard of a lot of VC17 users. And yes I actaully just grinded al lthe rust away...Lots of shiny metal now.

So do people really raise their boat off their trailer and take the entire swing keel off every year or 2 years? That seems a bit much to me. I can see doing the whole thing and taking the keel off every 3 or 4 years to re coat and to maybe replace the 4 bolts that hold it to the hangers just to be safe and keep them from breaking inside there (they're cheap).

Also I worry about what kind of paint the original owner used and how my new application will transition into the old unknown paint..? (what if its not compatible..)

Now that it’s stripped you should have no concerns with compatibility. You can use whatever you want.
No - few people dismount a swing keel for bottom paint touch ups. It’s a one-and-done job for most people and once the board and inside of the trunk are painted they don’t concern themselves with maintaining it unless it’s binding up too much from marine growth or rust. Even then, most people will use tools or a steel scrap flat bar to keep things moving and only use bottom paint on areas accessible without dismantling it.
Practically speaking, the bottom paint will scrape off in the contact areas the first few times you use it. After that, using it is the best maintenance, as using it will crush most marine growth that could otherwise interfere with the raising and lowering. It’s only going to develop problems if you let it sit still too long (multiple weeks, or more, depending on your area).
Most people’s annual maintenance will be power washing at end of season to remove growth, scraping any hard growth, and getting the boat as high as possible in Spring to expose as much centerboard as possible to add another coat of bottom paint. If you’re not racing seriously there’s no need to fret too much about rough surfaces inside the centerboard trunk.

 

[Timm R Oday25]

As long as you have it out and ready to prep . I would coat it with something like POR . For myself ,protection from rust is more important than bottom paint.Por-15 applied immediately after removing all rust will keep the 650 pounds swing keel in great shape for years to come . We kept our Catalina 22 on Lake Michigan like this .

 

[Carl Wonderful]

Now that it’s stripped you should have no concerns with compatibility. You can use whatever you want.
No - few people dismount a swing keel for bottom paint touch ups. It’s a one-and-done job for most people and once the board and inside of the trunk are painted they don’t concern themselves with maintaining it unless it’s binding up too much from marine growth or rust. Even then, most people will use tools or a steel scrap flat bar to keep things moving and only use bottom paint on areas accessible without dismantling it.
Practically speaking, the bottom paint will scrape off in the contact areas the first few times you use it. After that, using it is the best maintenance, as using it will crush most marine growth that could otherwise interfere with the raising and lowering. It’s only going to develop problems if you let it sit still too long (multiple weeks, or more, depending on your area).
Most people’s annual maintenance will be power washing at end of season to remove growth, scraping any hard growth, and getting the boat as high as possible in Spring to expose as much centerboard as possible to add another coat of bottom paint. If you’re not racing seriously there’s no need to fret too much about rough surfaces inside the centerboard trunk.

The compatibility concerns I have are because I'm only repairing the 15% of the keel that was rusty...the other 85% if fine and has whatever combination of primer/fairing/epoxy/bottom paint??? that the old owner used. So I'm worried about how I transition into the old, good, already painted areas?

I do have the keel completely off but I am not redoing the entire keel cause most of its in good shape.

 

[Captain Larry-DH]

snip
I do have the keel completely off but I am not redoing the entire keel cause most of its in good shape.

I looked again at your pictures and you should do at least a scuff sanding to recoat the entire keel. Considering you aren't racing I recommend Pettit Hydrocoat. It's a multi-season ablative that doesn't lose potency if you haul out and store the boat on a trailer, is compatible with almost every other bottom paint (other than teflon based paint) and it's water based, easy to apply (low VOC) and clean-up is with water.
Whatever you use will wear off in the first few uses where it rubs the centerboard trunk, so don't worry too much about durability - they're ll going to fail from abrasion.

 

[capta]

The compatibility concerns I have are because I'm only repairing the 15% of the keel that was rusty...the other 85% if fine and has whatever combination of primer/fairing/epoxy/bottom paint??? that the old owner used. So I'm worried about how I transition into the old, good, already painted areas?

I do have the keel completely off but I am not redoing the entire keel cause most of its in good shape.

I would take the whole keel down to bare metal, then refinish the whole thing together, unless you only intend to keep the boat a year or two. You have no idea what might be going on under the paint still on there.
Understand that once bare steel is exposed to the air, the steel dust begins to oxidize in the pores of the metal immediately. To do the job correctly, I would work on small sections, not do the whole job at once.
I don't know if it is still available, but after the zinc chromate, or whatever anti rust product you choose to use, there was a tar-epoxy product than many steel boats used as an isolation coat. This might help with the wear from raising & lowering the keel.

 

[Captain Larry-DH]

I would take the whole keel down to bare metal, then refinish the whole thing together, unless you only intend to keep the boat a year or two. You have no idea what might be going on under the paint still on there.
Understand that once bare steel is exposed to the air, the steel dust begins to oxidize in the pores of the metal immediately. To do the job correctly, I would work on small sections, not do the whole job at once.
I don't know if it is still available, but after the zinc chromate, or whatever anti rust product you choose to use, there was a tar-epoxy product than many steel boats used as an isolation coat. This might help with the wear from raising & lowering the keel.

Hell no to tar-epoxy!
I recommend standard epoxy barrier coats Such as Interlux Interprotect 2000 or others by other paint brands, Totalboat Totalprotecct or Pettit Protect.
Many years ago I owned a boat with a cast iron keel (Shark 24). People in the Shark association recommended COAL TAR EPOXY. That stuff is evil. I couldn't get it smooth because when trying to apply it - it would start to sag and run before it "kicked". Then I'd have a mess of uneven coating. It dries to a tar and you can't sand it smooth without running into other problems. It fills any type of sandpaper or abrasive disk immediately, and grabs wire brushes or scrapers.
It would form crevices in winter and any keel corrosion (such as at the keel-hull joint) would expand beneath the tar. I owned that boat 8 years never did get it smooth and the ultimate solution would have been to hire someone to sandblast and start over with another more conventional epoxy barrier coat product. I was around 30 years old and didn't have the budget for that so I lived with "the best I could do" which wasn't good. I fought with that keel every Spring.

 

[Carl Wonderful]

I looked again at your pictures and you should do at least a scuff sanding to recoat the entire keel. Considering you aren't racing I recommend Pettit Hydrocoat. It's a multi-season ablative that doesn't lose potency if you haul out and store the boat on a trailer, is compatible with almost every other bottom paint (other than teflon based paint) and it's water based, easy to apply (low VOC) and clean-up is with water.
Whatever you use will wear off in the first few uses where it rubs the centerboard trunk, so don't worry too much about durability - they're ll going to fail from abrasion.

I was considering cleaning the 80% of the keel that was still "good" and then scuff sanding and re-coating the whole thing like you mentioned just wasn't sure cause I don't know what the old paint is... But if that Hydrocoat is compatible with most stuff maybe I'll give it a try. I did get a quart of VC17m that I was going to use to cover the keel cause a lot of people recommend that...but still worried if that will stick to he unknown old paint.

If I scuff sand the old unknown keel paint... hows that go... Would I just clean real good with totalboat dewaxer and surface prep, then sand with 80 grit with my power sander, then clean again with dewaxer and surface prep and then paint on the Hydrocoat? Sorry, I just need step by step instructions to really understand the process.

Also what makes the Hydrocaot multi-season...cause it says its ablative anti fouling paint that needs re coated each year?

Thank so much! Really appreciate everyone's help!!!! I've been going a little crazy trying to research and make sense of all this stuff!

 

[ShawnL]

I have my '74 on a mooring in a small bay in Lake Superior. The bay doesn't get much water movement. I've been using Total Boat Ablative bottom paint for the last 4 years or so and it seems to work well. I get some slime in August, but if it bothers me too much I just hit it with my boat brush. In the fall I pressure wash the bottom in the backyard and then again in the spring. Hit it with another coat and launch. At some point I'll have too many layers on there and need to sand.

For the keel, I slide underneath and get what I can with a cheap harbor freight brush. Same around the bunks, etc. Then roll the rest with a roller on a painter's pole.

 

[Captain Larry-DH]

I was considering cleaning the 80% of the keel that was still "good" and then scuff sanding and re-coating the whole thing like you mentioned just wasn't sure cause I don't know what the old paint is... But if that Hydrocoat is compatible with most stuff maybe I'll give it a try. I did get a quart of VC17m that I was going to use to cover the keel cause a lot of people recommend that...but still worried if that will stick to he unknown old paint.

If I scuff sand the old unknown keel paint... hows that go... Would I just clean real good with totalboat dewaxer and surface prep, then sand with 80 grit with my power sander, then clean again with dewaxer and surface prep and then paint on the Hydrocoat? Sorry, I just need step by step instructions to really understand the process.

Also what makes the Hydrocaot multi-season...cause it says its ablative anti fouling paint that needs re coated each year?

Thank so much! Really appreciate everyone's help!!!! I've been going a little crazy trying to research and make sense of all this stuff!

No, Hydrocoat does not need to be reapplied every year. Pettit | Hydrocoat. I’ve been using it more than 10 years and it is effective at least 2 years between coats, with power washing in between seasons. Sometimes I just power wash then let it dry and roll on another coat, sometimes I use a chip brush to touch up a thinning or scraped area between seasons. No need to dewax, I just brush or roll it on.
Pettit might be more careful about specifying better surface prep, but what I’ve doing works for me on my boats. Hydrocoat is excellent on a fiberglass RIB also. It doesn’t hurt the Hypalon fabric and adheres even though it flexes - of course it’s good on the fiberglass too.
As for VC 17 - that’s got non-stick additives. Interlux words it as follows: “Thin film with a fluoro-microadditive creates a smooth, low-friction surface, ideal for racing and cruising boats”.
I would check with any manufacturer before applying another paint over VC17. If I knew my boat has VC 17 on it I would either use VC17 again, or completely strip it before using a different paint.

 

[Tally Ho]

I would check with any manufacturer before applying another paint over VC17. If I knew my boat has VC 17 on it I would either use VC17 again, or completely strip it before using a different paint.

You can’t put another paint over VC17.

But I believe it will stick to a previous paint, as long as it is clean and scuffed up a bit.

Greg