Beneteau Keel bolts - Page 3 - SailNet Community
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post #21 of 66 Old 08-27-2018
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Re: Beneteau Keel bolts

The keel bolts are3 designed to carry 7 times the weight of the keel.
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post #22 of 66 Old 08-28-2018
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Re: Beneteau Keel bolts

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Originally Posted by Lazerbrains View Post
According to the salvager, it "hit a reef".
At 5-6 knots that 2m keel makes one hell of a lever arm whacking into a bommie.

Depth everywhere else coulda been fine.

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Re: Beneteau Keel bolts

They recovered the keel. Pics attached.

The bolts are still intact. Fiberglass ripped apart. Not much backing for the bolts.
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40258793_10156046561011443_1144083230710824960_o.jpg   40325471_10156046561521443_3908079961986039808_o.jpg  
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post #24 of 66 Old 08-29-2018
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Re: Beneteau Keel bolts

The backing plates look bent up on the port side, giving the appearance of failure due to leverage from the side. Are there any pics of the keel that show where it was impacted? I wonder if it drove up onto a ledge, with the boat falling off to one side. Jury is out on whether this is a manufacturing issue or just a freak failure scenario. It will be very interesting to find out.

p.s. those keel bolts look better than mine (which are being replaced this Fall.


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post #25 of 66 Old 08-29-2018
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Re: Beneteau Keel bolts

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Originally Posted by zedboy View Post
Those French guys are dang good engineers. Lots of math, finite element analysis, safety factors.

But that's not how you attach a high-aspect, bulbed keel. This is how you attach a keel.

(the keel bolts to the bottom. the sides bolt to the longitudinal stringers. posted earlier today, from Francis Lee)
Is this picture relevant to the boat that sunk at all??? I sure do like this amazing structure. In wooden boat construction you would see this type of construction, those "beams" in a wooden boat would are called floors not to be confused with a floor, as you some of you may know a floor in a boat is called a sole.

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post #26 of 66 Old 08-29-2018
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Re: Beneteau Keel bolts

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Originally Posted by Lazerbrains View Post
They recovered the keel. Pics attached.

The bolts are still intact. Fiberglass ripped apart. Not much backing for the bolts.
What?
Shouldn't there have been some stringers across?
It couldn't just have been bolted through the laminate with backplates?

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post #27 of 66 Old 08-29-2018
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Re: Beneteau Keel bolts

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Originally Posted by celenoglu View Post
The keel bolts are designed to carry 7 times the weight of the keel.
That is just plain silly. Where did you come up with that idea? It makes absolutely no sense at all and bears no resemblance to reality. When dropping off a wave while heeled the side force on a keel and the sudden deacceleration can result in a tensile load on the bolts that can approach a range that is 20-40 times the weight of the keel. Or to look at this from another approach, each of those bolts has roughly a 50,000- 55,000 lb tensile strength and the keel only weighs 3748 lbs that is something in the range of 14 times the weight of the keel for each bolt.

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Originally Posted by Morild View Post
What?
Shouldn't there have been some stringers across?
It couldn't just have been bolted through the laminate with backplates?

If you look at the first set of pictures you can see that there are transverse frames (what Denise rightly calls floors) that are sheered off where they turn down into the bilge. The photos of the top of the keel show gaps where these frames were located and there torn fibers which are probably from the biaxial cloth used as reinforcing in this area of the boat and which were withdrawn from the hull and frames . Having the bolts through thickened laminate between the frames is pretty typical construction for a glass boat with a bolt on keel, but the failure mode is not very typical at all.


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Originally Posted by Minnewaska View Post
The backing plates look bent up on the port side, giving the appearance of failure due to leverage from the side. Are there any pics of the keel that show where it was impacted? I wonder if it drove up onto a ledge, with the boat falling off to one side. Jury is out on whether this is a manufacturing issue or just a freak failure scenario. It will be very interesting to find out.

p.s. those keel bolts look better than mine (which are being replaced this Fall.
I noticed the bent plates as well. It looks like there was a blow from the port side that pushed the keel towards the starboard. The port side of the base plates appear to have sheered downward through the laminate and were bent in the process. I still don't understand what happened have created such a clean cut. After all, even if the plates sheered down through the laminate, you would have expected the adjacent laminate to be peeled apart. Similarly, if the keel sheered upward from through the laminate on the starboard side you would have expected the transverse frames to be crushed on that side which they don't appear to be.

This looks like a lead keel and the paired bolts on a lead keel of this model are actually one U-shaped rod that is threaded on both ends to take a nut. The single bolts are J-bolts and you can see how well they faired with the aft bolt literally being torn out of the keel. Compared to many of the newer race boats, that is actually a pretty big root area.

It will be interesting to hear what is learned as the story develops.

Does anyone know if everyone on board was okay?

Jeff
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Last edited by Jeff_H; 08-29-2018 at 11:53 AM.
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post #28 of 66 Old 08-29-2018 Thread Starter
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Re: Beneteau Keel bolts

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Originally Posted by Jeff_H View Post
I still don't understand what happened have created such a clean cut. After all, even if the plates sheered down through the laminate, you would have expected the adjacent laminate to be peeled apart. Similarly, if the keel sheered upward from through the laminate on the starboard side you would have expected the transverse frames to be crushed on that side which they don't appear to be.

It will be interesting to hear what is learned as the story develops.

Does anyone know if everyone on board was okay?

Jeff
The keel hit a reef while under motor power. I don't think it is hard to understand why it failed. Occams razor = inadequate construction to sustain hitting a reef at 5kts. The fiberglass ripped cleanly away as it was not strong enough to sustain such an impact. Backing plates are woefully undersized - not much better than washers.
Other boats can wash ashore after a hurricane and keep their keel without the benefit of floatation. This simply looks bad for Beneteau, no easy way around it.
No one was injured, fortunately.

Last edited by Lazerbrains; 08-29-2018 at 12:14 PM.
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Re: Beneteau Keel bolts

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Originally Posted by Lazerbrains View Post
This simply looks bad for Beneteau, no easy way around it.
D'accord
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post #30 of 66 Old 08-29-2018
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Re: Beneteau Keel bolts

It's amazing to me that we don't hear about keel loss even more, the way people zip around without charts or knowing how to use electronics. Or even a basic of understanding how to read a chart.

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