Keelbolt Arrangement

[Sailmonkey]

Originally Posted by CassidyNZ

Which would imply that the steel structure is visible from the outside? Sure doesn’t look that way from the pictures.

That the keel is attached to the boat via a stainless structure is patently obvious. My point is that the keel appears to be fitted to the boat without any sign of it coming loose or separating from the hull and has been that way seemingly for decades. Yes, I understand that such an unusual structure could invoke mild paranoia but it appears to be working.

The same mild paranoia could exist with standard keel bolt arrangements, not knowing how they’re attached to the keel, what condition they may be in where they can’t be see and so on. But generally a buyer would make a judgement call on what can be seen.

My point (again) is that the OP is making judgement calls based on pictures taken decades ago and not on what is visibly evident today.

No, but the welded structure is apparent in the build photos. And being that the welded structure is external to the hull there is higher probability that it’s degraded over the years.

Keel bolts follow a fairly well understood path, a welded,embedded, submerged structure is not quite the same animal.

[Knotical]

If the seller is confident of the structure and does not see it as a defect then he should allow you to have it inspected. The seller not agreeing to dropping the keel (even at your expense) would certainly raise red flags.

Question: did the manufacturer make all boats like these or this one is an outlier?

[Muaddib1116]

I am not a boat building expert, or a metalurgist, or a corrosion expert. I do have a degree in mechanical engineering and I have experience in manufacturing for aerospace and medical devices where the only way to prove that the product worked was to test it destructively. These types of products are sold on their paperwork which proves that they were built according to statistically tested capable and qualified processes. And even then, there are in-process inspections that you rely on as indicators for process accordance.

To me, bolt on keels are similar. The long use and low failure rate of bolt on keels among hundreds/thousands of cruising boat designs, each with many builds, over many many years, is a data population that gives me confidence that the established bolt-on methods deserve a certain amount of trust. Even then, there are risks that you try to mitigate by inspecting the visible portion of the keelbolts.

I have done as much research as I can, and I have found no other examples of similar keel attachments like I've discovered with this boat. There are not thousands of examples of similar designs that have proven themselves that give me confidence that this will continue to be fine.

Even though it has clearly been fine for the last 23 years, I am not buying the last 23 years of this boat, I am buying the future of the boat, and my understanding of crevice corrosion is that it is not necessarily a gradual failure. How many stories of encapsulated chainplates suddenly failing have we all heard about? Except, if this thing fails, and the keel falls off, I probably have a bigger problem than a loose shroud or even a broken backstay.

[robert sailor]

Originally Posted by navdi

If the seller is confident of the structure and does not see it as a defect then he should allow you to have it inspected. The seller not agreeing to dropping the keel (even at your expense) would certainly raise red flags.

Question: did the manufacturer make all boats like these or this one is an outlier?

I have to say if I was selling a boat and someone who was wanting to buy it made it conditional on dropping the keel I'd show him the door.

[Muaddib1116]

Originally Posted by navdi

If the seller is confident of the structure and does not see it as a defect then he should allow you to have it inspected. The seller not agreeing to dropping the keel (even at your expense) would certainly raise red flags.

Question: did the manufacturer make all boats like these or this one is an outlier?

As logical as that may sound, I have a hard time imagining that he would allow that while he is still the owner. Would you be ok with a buyer, even one that has paid a deposit, asking to do something like this. I'd like to think I would be that reasonable, but somehow I doubt it's a foregone conclusion. I'm trying to get as much information and advice as I can, before I bring this up with the owner and put the deal at risk. I will, if I can't find anything to settle my doubts, but I'm not ready to yet.

I am waiting on the builder to get back to me with some more information about it.

[robert sailor]

Originally Posted by Muaddib1116

I am not a boat building expert, or a metalurgist, or a corrosion expert. I do have a degree in mechanical engineering and I have experience in manufacturing for aerospace and medical devices where the only way to prove that the product worked was to test it destructively. These types of products are sold on their paperwork which proves that they were built according to statistically tested capable and qualified processes. And even then, there are in-process inspections that you rely on as indicators for process accordance.

To me, bolt on keels are similar. The long use and low failure rate of bolt on keels among hundreds/thousands of cruising boat designs, each with many builds, over many many years, is a data population that gives me confidence that the established bolt-on methods deserve a certain amount of trust. Even then, there are risks that you try to mitigate by inspecting the visible portion of the keelbolts.

I have done as much research as I can, and I have found no other examples of similar keel attachments like I've discovered with this boat. There are not thousands of examples of similar designs that have proven themselves that give me confidence that this will continue to be fine.

Even though it has clearly been fine for the last 23 years, I am not buying the last 23 years of this boat, I am buying the future of the boat, and my understanding of crevice corrosion is that it is not necessarily a gradual failure. How many stories of encapsulated chainplates suddenly failing have we all heard about? Except, if this thing fails, and the keel falls off, I probably have a bigger problem than a loose shroud or even a broken backstay.

I certainly understand your concern about crevice corrosion. I'm not even a believer of using stainless studs in a keel for that reason. You might want to look into X Yachts who build a nice boat. They use a metal structure in a grid to pick up the keel as well as side stays. If my memory serves me correctly, I think they started using galvanized steel and recently switched over to stainless steel but I don't know the grade of steel. It might be easier to catch someone to talk to there now that everyone is at home.

[Jim Cate]

I don't think that any of us are competent to predict the future of that keel assembly without inspection. However, I can predict that should you buy her without inspection, YOUR future will be full of anxiety, peaking during harsh weather when you should be concentrating on other matters. Is that an acceptable future for you?

In all the places I've been around boat sales, contracts had wordage allowing the buyer out if the boat failed to satisfy in survey or sea trial, and the decision was the buyer's, not the sellers to determine satisfaction. I suppose Sweden could be different, but somehow I doubt it. In your place, I'd be considering finding out the details of your situation with a Swedish attorney.

Jim

[Muaddib1116]

Yeah. I am currently looking for 3rd party professional assessments on it, as well as a few possible options to inspect it or remove it in the future. Basically, if I can't find a way to get comfortable with it, I will have to walk away.

[robert sailor]

Originally Posted by Jim Cate

I don't think that any of us are competent to predict the future of that keel assembly without inspection. However, I can predict that should you buy her without inspection, YOUR future will be full of anxiety, peaking during harsh weather when you should be concentrating on other matters. Is that an acceptable future for you?

In all the places I've been around boat sales, contracts had wordage allowing the buyer out if the boat failed to satisfy in survey or sea trial, and the decision was the buyer's, not the sellers to determine satisfaction. I suppose Sweden could be different, but somehow I doubt it. In your place, I'd be considering finding out the details of your situation with a Swedish attorney.

Jim

Your right about the anxiety Jim. Not that recently I got it in my head that after close to 30 years I should really be thinking about changing out the mild steel keel bolts but I stored them on the boat and put it off for a year. Everytime we ran into crap weather after that the first thought was those damn keel bolts. Finally I changed them this year. The factory original studs were in near perfect shape and would likely have gone another 20 years but I no longer think about it.

[Fore and Aft]

Maud was there any paperwork presented to you when you asked about the keel? At the very least I would expect there to be engineer drawings and then a qualified engineer has signed of on the quality of the welds? But realistically after 20 years I would want all those welds inspected before I was happy.
What I find interesting is the lateral thinking that has gone into this keel extension. I have never seen this done before and I wonder why they did not just pour a new keel with an extra 100mm of ballast and bolts at the top? Surely the keel mould would have still been around back then? Or even drilled out the bolts (Hole saw with a pipe welded to it, yep its hard work to drill) put in pockets and nuts then filled the top with either another 100mm lead sandwich or fiberglass sandwich?
Cheers

[donradcliffe]

Speaking to engineer to engineer, the fact that there is NO telltale signs of corrosion discoloration in the stub keel, and the fact that it is MUCH more likely that any leakage of salt water into the fabrication below the stub keel would have come from water sitting inside the stub than through the fiberglass sheathing of the stub, I would say that the welds are likely to last your lifetime.

If you want further assurance, than a test by boring into any one of the cavities below the stub should either eliminate corrosion concerns or dictate that you test all the cavities.

[erie]

Originally Posted by Muaddib1116

Hi guys, I am under contract to purchase a 52' sailboat, and in the course of the initial on-land survey I got these pictures of the keel/keelbolt arrangement that I think were taken during the initial construction in 1997. I've never seen a setup like this, and am hoping to get some opinions of the pros and cons of it. Given where the internal access to the keelbolts is, it seems like they are about a foot down the keel in a keel stub.

Walk away there are other boats out there..

[Coltrek]

I have been in the marine SS welding business all my life, and I am old. Well, kind of. What you are going through reminds me of the second guessing I went through with my last two marriages. And, yes, I should have walked away at the get-go, which Is what I am suggesting you do. The boat I have became available after someone before me backed out, and all he lost was the cost to launch the boat for a trial, and his survey. I was told, even when selling my last boat, that the prospective buyer could walk at any time and take his deposit. Maybe things are different in Sweden, but I would let the deposit go, there are just too many really good boats out there, and really cheap. And with all this crazy **** going on now, getting cheaper.

[svandante]

Not an easy task but can’t the stainless structure be X-Ray’ed (or Gamma Ray’ed)? Navy and commercial yards do it regularly. I know the angles would present a problem but can’t hurt to consult with an expert in the field. Ultrasonic testing could also be an option for non destructive testing.

[MerMike]

Go with your instinct on this one. The deposit may or may not be a fight, you don't know that yet. You DO know you don't like the keel arrangement.

Originally Posted by Muaddib1116

In response to some question that came from the survey, I was sent these pictures. I am not really concerned with the structure of the bolts. What I am concerned with is corrosion. My understanding is that corrosion can result in unexpected and sudden failure, even when things have been "fine" for a long time. Basically, there is a certain amount of corrosion risk with a normal keelbolt attachment method. This unusual setup adds a whole bunch of different risk avenues, and it seems impossible to inspect without dismantling. That is why I'm not fully comfortable with it.