Cast iron keel problem! Advise needed

[timot]

Hello All,

I really need your advices or suggestions from experts...

Last year in May 2022, I bought a Dufour Gib Sea 33 from 2000 and during the survey, the surveyor just noticed that my boat needs to be sanded till gelcoat and do the antifouling from scratch. (Previous owner did the antifouling by himself and did it very badly...)

Yesterday I took the boat off to do antifouling, and while observing the keel, I saw a crack and with little force the part just came to my hand. (Please see the photos..)

I am now truly worried if this is a big problem or not. For now, the paint company did only one layer antifouling and covered the broken part with epoxy. Asking me to come in October after the summer and fix things properly. I am also attaching the photos of fix...

I am not sure what to do now, according to people in the yard the boat has an electrolysis problem and it resulted in this and advicing me to do a check when the boat is again in the water. And I dont know what to do, my biggest horror is that the keel goes off one day while sailing....

Could you please have a look at the photos and advice what to do! Thanks from now...

I also add photos from the bilge, there are 11 stainless steel screews holding it, the setup: 1-4-4-1-1

[neilpride]

If the entire upper part that join to the hull is in the same condition, I think you need a new keel.

[timot]

Originally Posted by neilpride

If the entire upper part that join to the hull is in the same condition, I think you need a new keel.

Do you know there is a way to check it? I will ask for a surveyor to look at it.

[Icarus]

Originally Posted by timot

Do you know there is a way to check it? I will ask for a surveyor to look at it.

It is only the small tail piece which broke off, the thread for the keel bolt is too far to the end of the fin...bad design.
Bolt on keels always 'work' that's why the last few inches are not rigid..
Anyway your keel won't fall off.
I have done a number of ballast keel repairs on Beneteaus..
In your case I would eventually lift the yacht off the keel and check for possible cracks in the cast iron keel.
No, u don't need a new keel.

[Ballsnall]

Originally Posted by Icarus

It is only the small tail piece which broke off, the thread for the keel bolt is too far to the end of the fin...bad design.
Bolt on keels always 'work' that's why the last few inches are not rigid..
Anyway your keel won't fall off.
I have done a number of ballast keel repairs on Beneteaus..
In your case I would eventually lift the yacht off the keel and check for possible cracks in the cast iron keel.
No, u don't need a new keel.

At last, someone who knows what they are talking about. Check the tension on your keel bolts, other that that it's just a cosmetic issue.

[timot]

Originally Posted by Icarus

It is only the small tail piece which broke off, the thread for the keel bolt is too far to the end of the fin...bad design.
Bolt on keels always 'work' that's why the last few inches are not rigid..
Anyway your keel won't fall off.
I have done a number of ballast keel repairs on Beneteaus..
In your case I would eventually lift the yacht off the keel and check for possible cracks in the cast iron keel.
No, u don't need a new keel.

I have asked many techs around and they say it is impossible to weld, even it is welded it can be cracked easily one day. Which method were you using to repair?

[Ballsnall]

Originally Posted by timot

I have asked many techs around and they say it is impossible to weld, even it is welded it can be cracked easily one day. Which method were you using to repair?

Cast iron can be easily welded with the correct technique's but in this situation they are correct, it would fail again due to the poor design. The only repair needed is to just cut off the jagged edge and add a fairing piece in the same shape as the broken piece. Use a sikaflex joint between the keel and the fairing piece to allow for some movement.

[neilpride]

Get a chisel, hit the joint, until you see healthy iron, another idea can be ultrasonic testing.

[RaymondR]

First thing to do is clean it off and dye check it to see if it has other cracks.

[bil56]

poor quality cast iron + probably corrosion + possibly shock (check the bottoms), it's worrying ...

[neilpride]

Jezz, pic number 3, is that a bolt sticking out?

You definitely have to lower the keel, sorry to be pessimistic, but if that is the bolt you see, you're screwed.

[neilpride]

If I were in your place, I would call Mars Keels, send them the photos and they will advise you or give you a quote.

[MicHughV]

Have to echo neilpride's view...that 3rd pic shows the keel bolt in plain sight.....and that's what you see....no telling what you can't see elsewhere...

Also note the rust under the keel bolt washers....another "sign" of potential problems elsewhere

I wouldn't sail this boat anywhere....seriously....

Don't second guess the situation....have the keel dropped for a closer look...it's a bummer.....but the keel issue needs to addressed.

[boatpoker]

I feel for you, i just went through a 4 month $60k horror story myself.
Take Neils suggestion and call the keel manufacturer tho' I don't think it's Mars as I've been through their plant and they don't do iron castings.

Also don't take advice from anyone who uses the word "electrolysis". Electrolysis is an induced process found in industry and laboratories in which the anode is positive and the cathode is negative whereas on your boat it’s the anode that is negative and the cathode which is positive … it simply cannot occur on a boat.

[double u]

Originally Posted by boatpoker

I feel for you, i just went through a 4 month $60k horror story myself.
...Also don't take advice from anyone who uses the word "electrolysis". … it simply cannot occur on a boat.

easy there!
While "electrolysis" of course is used falsly (the problem usually is "galvanic corrosion"), "electrolytic corrosion " (which is meant by "electrolysis) does exist:
https://www.belmontmetals.com/galvan...h-zinc-anodes/