Keelbolt Arrangement

[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.

[slug]

It looks like a mess

I can’t figure out what going on

If that is indeed how the keel is mounted contact a naval architect immediately for advice or reject the boat

[tkeithlu]

I suppose the important question is "Why add four inches to the height of the keel?" The new bolts replicate the lower bolts, just offset so they don't collide. Did the manufacturer perhaps also build a slightly smaller boat, and use the same keel for both?

Beyond the unusual (I've never seen one, either) add-on, they did not skimp on the bolts or the add-on frame. Probably as strong as any keel of the type - not what you want to hit a rock with.

[Muaddib1116]

I am trying to contact the original builders to get some information on why they did it that way. It certainly looks robust, but I have concerns about corrosion. Is there anyone specific that anyone recommends to get an opinion on it?

[wingssail]

This looks very similar to the Ker 40 keel structure that failed this January in which the top plate remained attached to the hull but the weldment failed and the keel dropped off at sea.

Jason Ker was quick to report that the actual structure used was not to his design.

This points out the need, in the case of the OP's boat, to remove that keel and very closely inspect the weldment.

[slug]

It looks like they changed their mind after the keel was built

Keel is deeper and moved aft

The whole contraption is a mess

Common keel bolt pattern

[Muaddib1116]

I have not closed on the boat yet. I don't think the owner will agree to drop the keel, even if I offer to pay for it. How much would that even cost?

[wingssail]

Originally Posted by Muaddib1116

I have not closed on the boat yet. I don't think the owner will agree to drop the keel, even if I offer to pay for it. How much would that even cost?

The boat is 22 years old. There is in my opinion a possibility that saltwater intrusion has occurred in that keel structure, and consequently the possibility of corrosion in the welds, in an area which is not easy to inspect.

The cost estimate must come from the boat yard which will have to put stands on the keel, then, while hanging the boat in the slings, unbolt the keel and raise the boat off. Assuming no difficulties getting access to the interior keel bolts and that they loosen easily, I think this is a one half to one day job for 2-4 workers, plus the cost of operating the travel lift.

After inspection, and again assuming the best that no problem is found, the operation must be reversed.

So, maybe in the order of $2000 to $3000, NOT including hiring some specialist to inspect and dye test the keel structure.

I think this is essential since the safety of the boat depends on a welded structure which cannot be easily observed and monitored.

[robert sailor]

Don't get into cost...if something had to be done it's a real sizable number. That said why don't you send pictures of the bilge area of the boat so we can see what actually got built. May not be like the picture you have from the builder.

[wingssail]

Originally Posted by robert sailor

Don't get into cost...if something had to be done it's a real sizable number. That said why don't you send pictures of the bilge area of the boat so we can see what actually got built. May not be like the picture you have from the builder.

Whether or not the keel was built as pictured can be determined in an instant: If you see keel bolts with nuts then it is a normal keel bolt attachment. If you see the heads of hex head bolts then it is as pictured.

[Muaddib1116]

Originally Posted by wingssail

Whether or not the keel was built as pictured can be determined in an instant: If you see keel bolts with nuts then it is a normal keel bolt attachment. If you see the heads of hex head bolts then it is as pictured.

I'm not sure that is true. The hex head bolts in the above pictures would come through the keel stub looking just like keelbolts. Here are pictures of the inside of the keel stub/bilge. I am not sure if these pictures were also taken in 1997 or if they were taken more recently.

[CassidyNZ]

Originally Posted by wingssail

Whether or not the keel was built as pictured can be determined in an instant: If you see keel bolts with nuts then it is a normal keel bolt attachment. If you see the heads of hex head bolts then it is as pictured.

Clearly this method of attachment would present studs/nuts inside the boat as would any “normal” keel bolt arrangement. The studs are evident in the pictures.

Looking at the picture of the underside of the hull, the ladder section picture must be embedded into slot on the underside of the boat. This has no effect on the length of the keel so the purpose of such a device is lost on me.

Having said that, if the ladder section had been embedded into keel instead, it would have presented the same structural uncertainties but would not be visible and would resemble any other bolted keel I’ve ever seen.

I would personally have reservations as the ability of thus structure to resist lateral flexing over an extended period.

[Muaddib1116]

I've gotten a brief response from the original builders in Finland. He says that the reason they did this was to increase the draft and secondarily to move the keel back a little bit to balance the boat because of heavy equipment in the bow. The way he said it makes me think the secondary reason was more of a rationalized additional "benefit" after they decided to do this to increase the draft. I have asked whether this was done sometime during the original build process or sometime afterwards as a modification, but I haven't heard back yet.

I'm not overly concerned with the structural strength of the steel frame as designed, but I am very concerned about a drastic increase of crevice corrosion that is not able to be inspected on a regular basis. Primarily, the fact that there are a lot of welds, and my basic understanding of crevice corrosion makes those welds prime targets.

[slug]

Originally Posted by Muaddib1116

I've gotten a brief response from the original builders in Finland. He says that the reason they did this was to increase the draft and secondarily to move the keel back a little bit to balance the boat because of heavy equipment in the bow. The way he said it makes me think the secondary reason was more of a rationalized additional "benefit" after they decided to do this to increase the draft. I have asked whether this was done sometime during the original build process or sometime afterwards as a modification, but I haven't heard back yet.

I'm not overly concerned with the structural strength of the steel frame as designed, but I am very concerned about a drastic increase of crevice corrosion that is not able to be inspected on a regular basis. Primarily, the fact that there are a lot of welds, and my basic understanding of crevice corrosion makes those welds prime targets.

Keel wings cause the boat to “ trip “ on the wing

To overcome this tripping you need more ballast in the keel or a deeper keel

Wing keels are bad news

They were fashionable 20 years ago , not now

[Muaddib1116]

Originally Posted by slug

Keel wings cause the boat to “ trip “ on the wing

To overcome this tripping you need more ballast in the keel or a deeper keel

Wing keels are bad news

They were fashionable 20 years ago , not now

I'm not sure what that has to do with this thread, but I've never heard that before. Can you explain what you mean by "trip"?