Rust on Keel I need Help.

[skipperclaud]

Hello guys, I need help with a situation on my keel, I took my Hunter 36 2008 to a bottom paint and some hull fixings on December 2022. While in the yard, I saw rust coming out of the wing part of the keel where it connects and fastens to the vertical. I contract the boatyard crew to analyze and treat the issue. They sand it to the core metal, and a rep from a paint brand came on-site and recommended Two coats of TUFF STUF epoxy-based. Yesterday I lift the boat for a couple of hours and me and the boat yard manager got mesmerized, check out the pictures, please!
Do any Hunter owners has experience with this issue that could help me out. I confess that I am lost.
Thank you so much!!!

 

[shemandr]

Most of the keel looks good. It's mainly the junction between the wings and the keel or close to that. I'd look closely to see if that the wings were attached after market. As an aside factory boats don't have that carefully sculpted wing shape for the most part. And that's not really what a Hunter wing looks like. At least not mine.

 

[Sailfanatic]

I have prepped two iron keels in the past and found the only way to control rust is to coat with five or so layers of straight epoxy. Products such as Interprotect 2000 are not hard enough to protect iron, and I'd say two coats of anything is not thick enough even if hard.

 

[dLj]

There are fundamentally two ways to protect underwater steel structures:
1) Cathodic protection (think sacrificial anodes/impressed currents)
2) Completely seal so corrodents are not in contact with the steel (coatings).
These two are also often used together.
No matter how you do it, it requires periodic maintenance.

I agree with both @shemandr and @Sailfanatic - those wings sure don't look "factory" and two layers of amy coating seems insufficient...

But that sure is a beautiful keel! I'd guess you'd rather not build sacrificial zincs onto that structure (and impressed current is way too complicated). So you are left with encapsulation.

I would clean to bare metal and treat the bare metal surface with Ospho. Be sure to follow all post-application cleaning instructions for the Ospho treatment. Then I'd apply your epoxy coatings. Be sure to check if the epoxy coating states compatibility with the Ospho surface treatment, some claim you shouldn't use their product over Ospho. Ospho is a phosphoric acid based product that converts iron oxide to iron phosphate. Iron phosphate is a hard inert coating that will not support continued oxidation. If you clean to bare metal and don't coat with the epoxy right away, you can get small oxidation spots that can degrade under your coating and cause rusting to take place under your epoxy. Also, the cleaning process is hard to be sure you get things really "clean".

dj

 

[skipperclaud]

Most of the keel looks good. It's mainly the junction between the wings and the keel or close to that. I'd look closely to see if that the wings were attached after market. As an aside factory boats don't have that carefully sculpted wing shape for the most part. And that's not really what a Hunter wing looks like. At least not mine.

Hey Brother Thank you for the reply. That is the original Hunter wing for sure, it changed after the 356 model. I gues you are right when saying that must to be a attachment issue.

 

[skipperclaud]

I have prepped two iron keels in the past and found the only way to control rust is to coat with five or so layers of straight epoxy. Products such as Interprotect 2000 are not hard enough to protect iron, and I'd say two coats of anything is not thick enough even if hard.

Agree 100%. Now I must decide if I remove that keel or not.

 

[skipperclaud]

There are fundamentally two ways to protect underwater steel structures:
1) Cathodic protection (think sacrificial anodes/impressed currents)
2) Completely seal so corrodents are not in contact with the steel (coatings).
These two are also often used together.
No matter how you do it, it requires periodic maintenance.

I agree with both @shemandr and @Sailfanatic - those wings sure don't look "factory" and two layers of amy coating seems insufficient...

But that sure is a beautiful keel! I'd guess you'd rather not build sacrificial zincs onto that structure (and impressed current is way too complicated). So you are left with encapsulation.

I would clean to bare metal and treat the bare metal surface with Ospho. Be sure to follow all post-application cleaning instructions for the Ospho treatment. Then I'd apply your epoxy coatings. Be sure to check if the epoxy coating states compatibility with the Ospho surface treatment, some claim you shouldn't use their product over Ospho. Ospho is a phosphoric acid based product that converts iron oxide to iron phosphate. Iron phosphate is a hard inert coating that will not support continued oxidation. If you clean to bare metal and don't coat with the epoxy right away, you can get small oxidation spots that can degrade under your coating and cause rusting to take place under your epoxy. Also, the cleaning process is hard to be sure you get things really "clean".

dj

thank you!! Yes it is a OEM keel! we cleaned it to the bare metal in december. I wonder if is a attachment problem and the rust attacked inside.

 

[Ralph Johnstone]

Just got to give my head a scratch here. I didn't think Hunter, Marlow, whatever, had every used steel in any part of their keels. Lead all the way.

That is the original Hunter wing for sure, it changed after the 356 model.

Can you quote your source for this ? Seems a little fuzzy around the edges. There is also a hot line to a coven of retired Hunter employees. Perhaps @Dave Groshong can chime in here and supply a phone number.

The most important question of all, have you run a magnet over the keel to detect exactly what metal is in there ?

 

[jssailem]

Perhaps it had an iron cable lying against the keel at some point.

 

[Ralph Johnstone]

@skipperclaud , can you supply a few closeup pictures of the joint. It may give us a better picture of what's going on.

 

[dLj]

Agree 100%. Now I must decide if I remove that keel or not.

Why would you remove your keel? You have a minor oxidation issue down near the transition between the vertical and wing portion of the keel. Did I miss images at the hull to keel joint? If the only problem you have is down near that transition, I certainly can't see any reason to remove that keel...

thank you!! Yes it is a OEM keel! we cleaned it to the bare metal in december. I wonder if is a attachment problem and the rust attacked inside.

The images you have at the beginning of this thread do not show enough detail to give any kind of useful advice beyond what has already been said. Is there a seam between the wings and the vertical portion of your keel?
dj

p.s. I'm apparently reading rather linearly...

 

[BigEasy]

Just got to give my head a scratch here. I didn't think Hunter, Marlow, whatever, had every used steel in any part of their keels. Lead all the way.

My 1988 Hunter 33.5 keel was entirely cast iron. No lead at all. At approximately 12 years , I had it blasted down to bare metal and encapsulated with epoxy. I see no reason to remove the keel. Blast the area that has rusted only, & reapply several coats of epoxy.

 

[Ralph Johnstone]

My 1988 Hunter 33.5 keel was entirely cast iron.

Best keep quiet and be happy with my all lead keel. I said "NUTHINNNNGGGGG"

I do agree with keeping the keel regardless of its composition. Just spend some time and money on ensuring it's well encapsulated. Same performance, just different material.

 

[Barnacle Bill]

Pettit has a product called Rust Lok Steel Primer. It is epoxy and silver and adheres to rusting surfaces very well, but you really need to clean the cast iron as best as you can and make sure there isn't any loose rust on it. They also marketed it as Trailerkote, for rusty trailers, but it is the same product. It is silver in color and if you get it on your bare hands, it will take about a hundred years to get off, so wear gloves and long sleeved shirts or work suits. You can then put Interprotect over it and paint with your fav antifouling paint.

 

[skipperclaud]

@skipperclaud , can you supply a few closeup pictures of the joint. It may give us a better picture of what's going on.

Sure, I will provide it. I got information about how Hunter treats the keel, and I will plan to do it ASAP. I will keep you all informed. But for sure what the boatyard did with only 3 coats of tuff stuff was not enough!

 

[skipperclaud]

My 1988 Hunter 33.5 keel was entirely cast iron. No lead at all. At approximately 12 years , I had it blasted down to bare metal and encapsulated with epoxy. I see no reason to remove the keel. Blast the area that has rusted only, & reapply several coats of epoxy.

I will do that thanks!!!