Delaminating Keel

[Ken GAMBILL]

I have not seen this issue come up on the forum.

My hull number is 99 and I have only had the boat in the fresh water of Lake Michigan.  Launched in 2014 so three summers.

Last year when I hauled out I noticed some blisters starting to appear on the lower portion of the keel.  They are primarily on the horizontal portion of the wing portion of the keel.  There are some small ones on the vertical portion.  The main ones are on the starboard side but there are some smaller ones on the port side.

Wondering if anyone else is experiencing this and have they tried to repair them?  Does anyone have any specifics on how they should be repaired?  I will be in Florida in a couple of weeks so I intend on stopping in at Catalina and also asking them.  

Again wondering if anyone else is experiencing the blistering.

Ken Gambill

LYFSA Gambill

Hull 99

2 attachments

[Delbert Patterson]

Hi Ken

About a week after Symphony was hauled out for the winter, I noticed a couple of small "blisters" in the fillet where the horizontal wing joins the vertical fin.  They were small, less that 1/4 inch in diameter.   I was able t squeeze a small trickle of water out of both of them with fingernail pressure.  The fore/aft location is just about the same as you show in your photos, but I don't have any of the open divots that you show.  Since we share the same marina, our fresh water environment is the same.  I suspect that water is infiltrating underneath some sort of fairing compound and lifting it off?

It'll be interesting to hear what you learn from the factory.

Del Patterson

Symphony

Hull 100

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[Ken GAMBILL]

Del---

I did visit the factory and asked about the voids or blisters that appeared on the keel. They said that without seeing the issues they really didn't have a good idea of what is happening. However, they would suspect that some portion of the barrier coat did not adhear and is coming off. They suggested getting a fiberglass guy in the area to look at it to see f he could determine what is happening.

Doug Ward from the site said he experienced the same issue on his 355. Doug filled in the areas with a two part epoxy filler -- Interluxs Watertite. I will most likely open up the blisters this winter and let them dry out. Then clean them again in the spring and fill them in with this Watertite filler. You are welcome to do the same and use some of my filler as I am sure I will not come close to using it all. Or you can wait until I pull out next year and see how the patch works and then determine what you want to do. The blisters have not grown significantly over a season and with where they are I do not see them causing any structure issue.

Take care and I am sure we will see you around the yard!

Ken Gambill
Lyfsa Gambill

[dworfel]

Ken, how large are the defects you've found in your keel? Have you opened them up? If you opened them up what did you find?

I have hull number 94. Last season, in the spring, I found a large, what looked like a blister, on the starboard wing of the keel. There was also a smaller defect just forward of the larger one. When I opened up the larger defect I found red sand. I cleaned out the large defect with a wire brush and coarse sand paper...same with smaller defect. I patched the defects with epoxy and high density filler and faired same. This spring I had 3 defects appear on the port wing. When I opened those I found red deposits. Repairs were the same as the previous year.

I raised the problem with the dealer, Sail Place, they contacted Mars Keels about the problem. Mars responded saying the red I found was Iron mixed in with the lead. I'm not buying it. A machinist friend who we told about the problem said I'd found foundry sand left from a mold that wasn't properly cleaned. I'm still pushing the issue with Sail Place.

[Ken Gambikl]

Howdy ---

The defects I had were various sizes. The smallest about 2 inches in diameter and the largest was about 6 inches by 4 inches. When I sanded, I found a covering material ( white epoxy) then the brownish clay.

The defects appeared to be voids in the casting. At first I thought they might be iron but the clay material got wet over night and clumped up like you expect clay to do. As I sanded the voids the clay revealed very irregular defects like you would expect in a poured mold like that.

I filled the voids in with West System epoxy filler and then covered it with a barrier coat and then VC17. This will be my first summer with the fix so when I take it out this fall I can report back on it.

I have done some work around castings. When I started sanding this down it looked exactly like the casting sand had been left in the void. They then just epoxied over the clay/sand mixture instead of cleaning it out first. My blisters never broke open but I just did not like them nor did I know at that time what was going on. In a couple of other areas just the opposite happened. They were defects in the sand cast so I have a slight hump on the keel. When I sanded on these, it remained shinny underneath. Again, none of this appeared to be iron inclusions in the castings so I think just clean then up, epoxy them, barrier coat them and go sailing.

I too got my boat from Sail Place. I did not contact them but I think you got a better response than I did from Catalina when I showed them the pictures.

Ken Gambill
#99
LYFSA Gambill

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[Mike Maksimchuk]

Resurrecting the Keel Blister Discussion – Hull #94 (Amadeus)

Dear Catalina 355 Owners,

I know it’s been quite a while since this topic has seen any activity (nearly eight years, in fact) but as I was preparing to launch this spring, I came across some familiar (and frustrating) signs on my keel that made me want to rejoin and reengage this thread.

As a bit of background: I’m now the owner of Amadeus, hull #94, which I inherited/purchased from my father-in-law, Dave Worfel. My wife and I have been sailing her for the past 4–5 years, and while we’re no strangers to boat ownership (we previously owned a Catalina 34), keel blistering is a new and highly unwelcome experience for me.

While painting the bottom this spring (with the boat already in the slings), I discovered several blisters on the keel. Several were the size of a quarter, one was the size of a baseball or so. Needless to say, repairs are going to have to wait until fall (it's already floating...), but it prompted a lot of questions—some technical, some philosophical:

• If I grind out the blistered areas and discover voids, am I better off refilling those with lead (e.g., melted and poured using a casting pot) to maintain weight distribution?
• Would lead poured into these voids bond or cause issues with expansion, adhesion, or some new form of corrosion?
• Or is it safer and more advisable to use epoxy filler (as others have previously done with Interlux Watertite, West System, etc.) despite the slight change in weight/density? With the epoxy over the metal, do we still need to barrier coat this?  (I am not sure, since Dave isn't around to ask any longer...)
• Has anyone tracked whether these voids and defects have had any long-term effects on sailing characteristics, ballast integrity, or resale conversations?

I’m still disappointed that these manufacturing voids appear to be common (enough) among our boats, and that there hasn’t yet been a clear resolution or acknowledgment from the people involved (Catalina Yachts, Sail Place, or Mars Keels). If anyone has recent insight, repair updates, or further context on how these issues are being handled, I’d love to hear from you.

Thanks for keeping this community alive. I look forward to learning from your experiences, and sharing my own as I go.

Fair winds,
Mike Maksimchuk
Hull #94 – Amadeus
Lake Michigan

(231) 225-5060

[Mike Maksimchuk]

Just throwing this back out there to see if there’s any suggestions or ideas besides what’s already in the forum archive. 

On May 18, 2025, at 14:52, Mike Maksimchuk <mtma...@mtu.edu> wrote:

Resurrecting the Keel Blister Discussion – Hull #94 (Amadeus)

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[bill pittore]

Hi Mike, 

Have you tried contacting Warren Pandy at Catalina? Possible he might have some insight to this problem. war...@catalinayachts.com

Bill

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