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post #41 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
In the case of the 36.7's there is a dense structural grid around the keel, that is integral with a grid that extend the length of the boat, and which also includes glassed in place longitudinal stringers in the hull. That combination would similarly spread the loads quite effectively in much the same way as Bob's design.
Jeff
Looking at the photos of the boat in question, it appears that the structural grid (which is hollow, not dense) in no way attaches to the keel - it provides structural form strength for the hull, yes, but does not attach in any way to those small backing plates - it simply tabs into the hull. Furthermore it can clearly be seen that the fiberglass bottom easily tore away from the one section of grid that was above the keel. As evidenced from the photos, it quite obviously did not "spread the loads quite effectively" as the hull broke quite cleanly at the small backing plates.
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post #42 of 66 Old 08-29-2018
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Re: Beneteau Keel bolts

the structural grid u channels are attached to the hull via a flange which is glued to the hull. the flange is part of the structure that is under the keel bolt backing plates, you can see in the pics the layers of hull, glue and structural grid if you what you are looking at.

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post #43 of 66 Old 08-29-2018
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Re: Beneteau Keel bolts

This has been an interesting thread. Thanks Jeff for your lengthy and detailed posts. I think there is more to come out on this failure. I am an engineer (but NOT a structural one) and I really have never liked the small attachment area of these kinds of keels. Yes the grid may stiffen the hull in the area where the keel is attached, but it just seems to me that keel needs a much larger flange to spread the load where it attaches to the fiberglass hull.

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post #44 of 66 Old 08-29-2018
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Re: Beneteau Keel bolts

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Originally Posted by JimsCAL View Post
This has been an interesting thread. Thanks Jeff for your lengthy and detailed posts. I think there is more to come out on this failure. I am an engineer (but NOT a structural one) and I really have never liked the small attachment area of these kinds of keels. Yes the grid may stiffen the hull in the area where the keel is attached, but it just seems to me that keel needs a much larger flange to spread the load where it attaches to the fiberglass hull.
Jim,

Thank you for the kind comment. I agree with you that I am not a huge fan of these high aspect, small footprint keels (or their tendency to stall out at slow speed). One of things about this particular design is that there is a flair to the top that spreads out the root footprint compares to many of the designs that follow it, and the center of the weight of the bulb is not a cantilever fore and aft.

Obviously as designers press the limits on high aspect keels this will only get worse. World Sailing has commissioned a major study on keel structure with a heavy focus on reducing failures. But it really does need to be looked at.

One of the bright spots is using 'cassette' type connections with these high aspect keels. These are essentially very heavily reinforced and completely integrated dagger board trunks that the end of the keel slots into. They are being used on race boats, and hopefully as high aspect keels move into the more mainstream, some form of cassette or other form of robust attachment method will be used.

Jeff


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Re: Beneteau Keel bolts

I want to toss this into the mix.

Fin keel boats are not blue water boats.

When a full Keel boat runs aground what happens? "Full Keel boat runs a ground"

Same scene; fin keel, "boat ran a ground, lost keel"

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Re: Beneteau Keel bolts

"Fin keel boats are not blue water boats.
When a full Keel boat runs aground what happens?"

Okay, I think you're radically missing a point here. In "blue water" you are not going to run aground, unless your fin keel is many hundreds or thousands of feet deep.

You know, there are very few hard bits that just protrude unseen within six feet of the surface, unless you count Iceland and Hawaii and a few others where new rocks do sometimes climb up.

And yes, the bottom gets closer in some few areas of the Pacific and Carib, but then again, those are fairly well known shoals and reefs, and there's no reason a blue water boat should have a problem there. That's a pilot error problem, not the boat's fault.

If you want to take "doesn't mind groundings" as a criteria, then your blue water boat can't be a fin keel either. It needs to be bilge keels, plural, so it can park anywhere. (and good luck getting it back off that reef.)
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Re: Beneteau Keel bolts

I'm sure there are lots of beneteau sailboats on sale. And it is not a new news that they lose keels.

Nope, boats also are lose their keels in the open oceans. some of the things weread and hear about make the ocean seem more full of obstructions and some of our harbors!

But I do agree, just about everything can be blamed on the nut holding the wheel

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Re: Beneteau Keel bolts

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Originally Posted by deniseO30 View Post
Fin keel boats are not blue water boats.
There are plenty of well respected bluewater boats with fin keels. Consider the Bob Perry designed Passport 40, Passport 41 and Valiant 40. Are these race boats with deep bulb keels like the Bene 36.7 being discussed in this thread? No. But fin keels, not full keels, just the same.

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Re: Beneteau Keel bolts

I love how y'all get so worked up on this issue, although you're all glad it wasn't your boat.

I don't think I'd ever go "out there" without a full Keel under my feet but that's just my personal feeling which, I'm allowed to have.
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Re: Beneteau Keel bolts

Denise-
Even if you were sailing a brick, with an integral full keel and steel hull, I suspect that if you ran it into a hard rock reef at seven knots, the mast and rigging would snap from the impact.
There's just no reason to design any typical boat to survive crashing into rock at hull speed. That would be like the DOT ordering car makers to build cars that can crash into highway abutments at highway speed, and still get back on the road with no harm to the cars or their occupants.
It probably COULD be done, but I don't think you'd want to build, buy, or operate one. That boat was severely abused. I'm reminded of the Porsche service manager in "Risky Business", after the car is dragged out of the lake: i.e. "And who was the u-boat commander?!"
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