First 29 rust pattern at keel

[Ducharme]

Hello all.

I've a 1985 Beneteau First 29 and there is an odd rust pattern approx 6" x 4" on either side of the encapsulated cast iron keel about where it joins the hull. When shopping I saw the same pattern on several other Beneteaus (285s and 305s maybe?). Anybody know what this is about/if it's a problem/how to remedy?

Thanks!

 

[Jackdaw]

The First 29 does not have an encapsulated iron keel. It is a cast iron keel, normally sealed in epoxy paint, that has been bolted on externally. Where that pattern is should be solid iron and under no particular load. Kinda weird.

 

[Ducharme]

Thanks for the correction. So encapsulated keels (I just learned) are continuous fiberglass construction with the rest of the hull with the ballast in said "capsule" of space. What you describe is certainly more in keeping with what I see: there is a section where the epoxy has cracked away exposing the cast iron.

It is weird. Especially in that I've seen it in multiple boats. What I don't see is any kind of seam where the keel joins the hull. I'm presently debating what I more terrified of: trying to change the keel bolts (imagine original) or potentially dropping the keel whilst underway....

 

[Apex]

I assume that is the keel joint. Many have steps rather than a single plane on the keel. This would show that 90° pattern. I have witnessed the same pattern in Hunters.

...found this using image search:

 

[Jackdaw]

I'm presently debating what I more terrified of: trying to change the keel bolts (imagine original) or potentially dropping the keel whilst underway....

Not much chance of that. While cast iron will surface rust if exposed to water, it is very durable. The bolts might rust, but that is from water that enters that area from inside of the boat.

If you don't see that hull/keel joint that means that it was well faired at the factory and still in great shape.

 

[Ducharme]

That's the kind of image I was just looking for. Things are starting to make sense. Especially because the other side looks like this:

So there's a breach in the epoxy coating, water bleeds through at the joint and rust registers at the other side tracing the outline of this keel key of sorts.

Which all makes my stomach sink--do I need to drop and rebed this keel? The big project this off season is to put on a copper epoxy bottom so whatever it goes on top of should be sound....

So when folks are talking about changing keelbolts, really from these images, it seems to be the case that we're talking about changing keelbolt nuts, no? Are the threaded rods typically cast in place with the cast iron keel?

Thanks to all for the help.

 

[Jackdaw]

I assume that is the keel joint. Many have steps rather than a single plane on the keel. This would show that 90° pattern. I have witnessed the same pattern in Hunters.

...found this using image search:

Very interesting. I've never seen that, and never on a beneteau keel.

 

[Apex]

Can't speak to First 29, but that pattern looks like a good indicator to me. I did some more searches and found the Bene 235 scantlings: It shows a step albeit wider, so the builder is not a stranger to a more complex keel to hull joint shape.
I like the idea personally, it would seem more surface area for bonding and shearing protection for the bolts. My O'Day has an encapsulated keel, no keel bolts.

For Ducharme: Try to identify how water is reaching the iron; if it is loose keel bolts (torque nuts) allowing an external crack, or migration through the bilge. i.e is the rust on the outside the root of the issue or symptom of a deeper issue type thing. There are many articles in repairing at both extremes from the catalina smile (caused by flexure of the hull at the keel stub) to dropping and rebedding keel. I have successfully repaired a catalina 25 using G-flex. It is still holding after 5years. The epoxy hardens to a flexible matrix, which is what I attribute to success.

 

[Sandy Stone]

So when folks are talking about changing keelbolts, really from these images, it seems to be the case that we're talking about changing keelbolt nuts, no? Are the threaded rods typically cast in place with the cast iron keel?

On most Beneteaus from that era (I have one), the keel bolts are tapped into the keel from above, there are no nuts. You can replace them one at a time, if necessary, with the boat in the water.

 

[Jackdaw]

On most Beneteaus from that era (I have one), the keel bolts are tapped into the keel from above, there are no nuts. You can replace them one at a time, if necessary, with the boat in the water.

Iron keels will have iron bolts. Lead keels will have SS nuts. Its a galvanic thing.

 

[Jackdaw]

Can't speak to First 29, but that pattern looks like a good indicator to me. I did some more searches and found the Bene 235 scantlings: It shows a step albeit wider, so the builder is not a stranger to a more complex keel to hull joint shape.
I like the idea personally, it would seem more surface area for bonding and shearing protection for the bolts. My O'Day has an encapsulated keel, no keel bolts.

I can tell you that the bottom of the hull of the 235 (and the 367) are totally flat in that area and have no structure to 'receive' any step. The keels I've seen for both boats are smooth on top.

 

[njlarry]

Do not get too stressed as your keel is not likley to fall off because of one bad bolt in non storm conditions. Make sure all the other bolts are solid and properly torqued. However it does need to be examined and corrected. I think that you would be helped by three sources, a competent surveyor, an experienced yard, and Sail Magazine has a series of articles in its online archive on keel attachments and repairs.
Good luck, likely the repair will only require at most one keel bolt replacement or sistering. Both are a whole lot easier on an iron keel than a lead keel. In a worst case, dropping a keel is not the end of the world.

 

[CloudDiver]

@Ducharme , just by looking at the pic and not seeing the condition of the keel bolts from inside the bilge;
There is a pretty good chance you hull/keel joint is fine and the bolts are in good condition. With your plans to copper-epoxy your bottom it would be worth it to have the keel sand blasted. After that you can visually inspect the joint, and if no problems then proceed with the copper-epoxy. Pro-tip, a rinse down with acetone will displace any moisture, do this immediately after the sand blasting is complete. Pick a warm (ish) and dry day to do it, and try to get the first coat of epoxy on immediately. Just the moisture in the air makes exposed cast iron start to rust instantly.

 

[Mechone]

last year when I pulled the boat had rust on the keel,sanded with flap wheel and grinder ,used rust converter and 4 coats of 2000e interlux.Pulled the boat this year more rust but not as bad(no big areas). Doing some research on the net people with cast iron keels have used this method and have gone 8 years plus with no rust coming thru.
Sand or blast keel , use POR rust converter then 2 coats of POR15 , followed by 4 coats of 2000e epoxy ,when last coat tacks up apply micron or vc17.

 

[firstsailor5IM]

Hello all.

I've a 1985 Beneteau First 29 and there is an odd rust pattern approx 6" x 4" on either side of the encapsulated cast iron keel about where it joins the hull. When shopping I saw the same pattern on several other Beneteaus (285s and 305s maybe?). Anybody know what this is about/if it's a problem/how to remedy?

Thanks![/

Just take a look if there is a kind of deepening in the inside of the hull under the floorboards (where the keel is fastened), if it is (may be there is even an bilge pump in that deepening) there is also a cut out in the topside of the cast iron keel.
In that case it means that there is some space between the polyester bilgepit and the iron keel where rust can arise.
A bolted keel means some (minimal) movement which is water-resistant compensated by the used sealant.
As a boat grows older it causes entry of water particles because of the deterioration of the sealing-paste.
Normally Beneteau attaches the keel to the hull with a paste which seals the seam between keel and hull and also protects the keelbolts. This construction is common practice with a lot of boat builders.
Scrape the seam between keel and hull as deep as possible, remove rust from the iron and seal with a good type of sealant as Sikaflex 291i or 292i upon an ample coat of Sika MultiPrimer Marine.

 

[Mechone]

Did the seam last year win 5200.when I pulled the boat it had released in a few areas.
People on other forums have sealed the joint with G Flex witch is stronger but still flexes Going that route this year

 

[NYSail]

Keel is not going to fall off..... I would sand it down to the metal and see what it is. It would be wise to fix it while it’s out of the water. Sand prep and put a good paint on it... forgot the paint I used on my iron keep but the places I redid last season look fine with no rust

 

[firstsailor5IM]

Second reaction on "rusting keel First 29" problem.
Yesterday it was possible to examine a First 29, freshly out of the water, she also showed the rust pattern as described. By knocking on several places on the surface of the keel with a small steel surveyors hammer it revealed a different kind of noise within the outlines of the rust pattern compared to other places on the cast iron keel. Further examining confirmed that the upside down trapeziumlike shape is caused by the polyester bilge that extends from the hull.
The firm importing the Beneteau boats from France confirmed the way of repairing the very small gap between keel and hull by means of a seawater resistant type of sealant like Sikaflex (I don't know whether it is sold in the US, in Europe it is). When there is no indication of rust traces caused by eventually rusting keelbolts , just repair and sail on happily for the years to come.

 

[CapitalistSailor]

Ducharme,

From what I see in the three pictures you posted, it looks like the epoxy coating has been scraped or gouged by something from the outside, possibly from something floating in the water or an underwater obstruction. If so, the simplest fix would be to grind down the coating around the gouge, grind off the rust from the metal, passify the rust with a rust inhibitor made for this purpose, and renew/repair the epoxy coating in this area.

I agree with Jackdaw. Cast iron is very durable and any rust on the exterior will be cosmetic. Rust does expand, however, (compared to the iron), and so if water gets into the space between the coating and the iron it will cause the coating to bulge out.

I suppose a sacrificial anode (zinc, aluminum, magnesium) attached to the keel or electrically connected might reduce the rusting, as that is what Navy ships do, but I'm not sure of its practical benefit to iron sailboat keels.

 

[Ducharme]

Many thanks to all for all the information and advice.

My update: indeed, that trapezoidal indention at the top of the keel would appear to be the bilge trap for the bilge pump. I believe that some combination of leakage here and at our keelbolts (several have severely deteriorated washers) allowed water through from the bilge and into the seam.

Didn't sand or sandblast but chipped the old epoxy away with a beater woodworking chisel and deadblow mallet. Fairly quick work but did show good adhesion through the bulk of the keel surface. Feel like it's worth the work in advance of the new copper epoxy bottom and did show signs of moisture intrusion that were not previously visible from the exterior (as seen in photo).

Now here's the funny thing I found: fiberglass. There is a section of glass cloth bridging the area between hull and keel, masking over the joint. Funny, right? I'd always read that there was a seam, and said seam was bedded with one's extremely durable compound of choice and then I expected that the next thing would be your bottom paint whatever that would be. But glass cloth???