Beneteau Keel bolts - Page 4 - SailNet Community
 12Likes
Reply
 
LinkBack Thread Tools
post #31 of 66 Old 08-29-2018
Administrator
 
Jeff_H's Avatar
 
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 8,628
Thanks: 28
Thanked 415 Times in 346 Posts
Rep Power: 10
     
Re: Beneteau Keel bolts

Quote:
Originally Posted by Lazerbrains View Post
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.
Do we know it hit reef under power? Do we know if anyone was hurt?

To me, if your conclusion is correct, this is far more serious than a Beneteau problem. The thing is that the 36.7 and 40.7 were not normal production racer-cruisers. Farr's office engineered these boats to be beyond the standard of the day, and an independent structural analysis of the 40.7 concluded that the both the engineering and the actual construction of the laminate and framing were capable of withstanding loads that are nearly 8 times those required by the current European standards, and which are much higher than the older ABS and D. LLoyds standards, which had been the previous standard.

Beyond that, these boats were subjected to a higher level of inspection and quality control than almost any production boat that I ever heard of, and higher than many if not most high quality limited production boats ever receive. And independent lab supervised the construction of the boats. The resin was weighed. Laminates were precisely cut and had placement and alignment patterns marked on the reinforcing. The pan/framing adhesive material and placement method was tested extensively before being used, and was machine placed and checked to assure proper coverage. Once the hull was laid up, actual samples of the hull were measured for thickness, layup and were burn tested for resin to reinforcing ratios. That just is not done even on extremely expensive limited production or custom boats.

So if you are correct that, " The fiberglass ripped cleanly away as it was not strong enough to sustain such an impact. Backing plates are woefully undersized", then that has serious implications for the vast majority of boats out there which are only designed to meet the basic structural standards and which are not the result of this high level of engineering, and or produced under the high level of supervision during construction.

But the other part of this is that these boats had a very sophisticated and complete framing system as compared to the vast majority of boats that are out there. That kind of framing should have been able to handle the service loads without allowing much flexure. (In fact when I sailed on 40.7's I was amazed at how little these boats flexed under heavy load in a steep chop.) The result of that stiffness is that by minimizing flexure these boats should lose less strength over its service life due to fatigue as compared to the vast majority of boat that are out there and which flexes more than these do.

So if your conclusion is right, the implication of all of this is huge on the industry as a whole. To put a finer point on this, since these boats were structurally designed well in excess of the current standards, which in turn are well in excess of the older standards, and when you consider that few older boats had anywhere near the rigidity, engineering and quality control of these boats, you would have to wonder about the safety the vast majority of boats out there, especially the older boats where the laminate materials and layup schedules were no where near what was used on these boats and which have been further weakened by a lifetime of fatique.

Jeff


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay

Last edited by Jeff_H; 08-29-2018 at 01:20 PM.
Jeff_H is online now  
Sponsored Links
Advertisement
 
post #32 of 66 Old 08-29-2018
Doesn't sail enough
 
zedboy's Avatar
 
Join Date: Jul 2010
Location: Eastern Med
Posts: 623
Thanks: 10
Thanked 31 Times in 31 Posts
Rep Power: 9
 
Re: Beneteau Keel bolts

Quote:
Originally Posted by deniseO30 View Post
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.
Quite right: this picture is from Bob's wooden Francis Lee - it's what he posted as an example of the right way to attach a keel.

'78 Dolphin 31
zedboy is online now  
post #33 of 66 Old 08-29-2018 Thread Starter
Senior Member
 
Lazerbrains's Avatar
 
Join Date: Oct 2015
Location: On a Boat
Posts: 877
Thanks: 10
Thanked 39 Times in 39 Posts
Rep Power: 4
 
Re: Beneteau Keel bolts

I dunno what you mean, Jeff, by "designed in excess of standards." What I see (quite clearly) is a keel bolted to a fairly thin,flat area of fiberglass with no sump nor much reinforcement, and woefully small backing plates that do not look to be up to the task of distributing the load very well. In fact, it is no suprise to me that the fiberglass ripped away right at the edges of the backing plates. This simply looks like weak engineering and most boats I have inspected seem better engineered than this. The pictures tell the story.
Lazerbrains is offline  
 
post #34 of 66 Old 08-29-2018
Senior Member
 
paulk's Avatar
 
Join Date: Jun 2000
Location: CT/ Long Island Sound
Posts: 3,141
Thanks: 4
Thanked 69 Times in 68 Posts
Rep Power: 20
 
Re: Beneteau Keel bolts

Saw on another site (Cruiser's Forum) that this occurred in Wisconsin, Door County(?) in Green Bay (the bay, not the city) with the boat, under sail in a 15-20 knot breeze, being run into Hanover Shoal. A Reef Encounter - Cruisers & Sailing Forums

If it was blowing that hard it's possible they were doing better than 7 knots when, WHAM!


Have subsequently seen comments saying boat was under power, not sail, when it hit. Photo on Cruiser's Forum shows what looks like an unfurled jib floating in the water, but others do show jib tightly furled on the forestay.

Last edited by paulk; 08-29-2018 at 03:49 PM.
paulk is online now  
post #35 of 66 Old 08-29-2018
Senior Member
 
overbored's Avatar
 
Join Date: Oct 2010
Location: Dana Point, Ca
Posts: 2,573
Thanks: 2
Thanked 185 Times in 182 Posts
Rep Power: 9
 
Re: Beneteau Keel bolts

I am not sure that making a supper stiff structure is a good thing for a fiberglass boat. stiffer is not necessarily stronger. they my have made the surrounding structure so stiff that it limited any flexing to a very small area which caused the fiber glass to break down from flexing fatigue just under the keel bolts. they caused a stress riser around the keel mounting area and when the keel hit something it let go all at once. a hull that flexes a bit will spread the load over a bigger area and not just snap off along a straight line. any time you have a stiff structure you will find the weakest link sooner the later.
Lazerbrains likes this.

"FULL TILT II" 2011 BENETEAU FIRST 30
"GOLD RUSH" PRINDLE 16
overbored is online now  
post #36 of 66 Old 08-29-2018 Thread Starter
Senior Member
 
Lazerbrains's Avatar
 
Join Date: Oct 2015
Location: On a Boat
Posts: 877
Thanks: 10
Thanked 39 Times in 39 Posts
Rep Power: 4
 
Re: Beneteau Keel bolts

Quote:
Originally Posted by paulk View Post
Saw on another site (Cruiser's Forum) that this occurred in Wisconsin, Door County(?) in Green Bay (the bay, not the city) with the boat, under sail in a 15-20 knot breeze, being run into Hanover Shoal. A Reef Encounter - Cruisers & Sailing Forums

If it was blowing that hard it's possible they were doing better than 7 knots when, WHAM!
That report is incorrect. Boat was under motor power, as evidenced by the foresail being furled and the mainsail cover still on.
Lazerbrains is offline  
post #37 of 66 Old 08-29-2018
Senior Member
 
overbored's Avatar
 
Join Date: Oct 2010
Location: Dana Point, Ca
Posts: 2,573
Thanks: 2
Thanked 185 Times in 182 Posts
Rep Power: 9
 
Re: Beneteau Keel bolts

there is pic on the last page of this ad of the internal support structure of a 36.7
http://www.curtisstokes.net/pdf/sail...hern-cross.pdf

"FULL TILT II" 2011 BENETEAU FIRST 30
"GOLD RUSH" PRINDLE 16
overbored is online now  
post #38 of 66 Old 08-29-2018
Administrator
 
Jeff_H's Avatar
 
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 8,628
Thanks: 28
Thanked 415 Times in 346 Posts
Rep Power: 10
     
Re: Beneteau Keel bolts

Quote:
Originally Posted by zedboy View Post
Quite right: this picture is from Bob's wooden Francis Lee - it's what he posted as an example of the right way to attach a keel.
While I personally would never question Bob Perry on any aspect yacht design, and that is a very robust way to attach a keel and may be the exact right way to attach a keel on a 60 foot wooden boat with a slender keel, its not the only "right way" to attach a slender keel. Now that Bob is working with carbon fiber, I assume that he would have a composite method of attachment if the hull was composite. And beyond that, the framing system used on the 40.7 and 36.7 are essentially composite versions of the keel attachment used on Francis Lee

Jeff


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
Jeff_H is online now  
post #39 of 66 Old 08-29-2018 Thread Starter
Senior Member
 
Lazerbrains's Avatar
 
Join Date: Oct 2015
Location: On a Boat
Posts: 877
Thanks: 10
Thanked 39 Times in 39 Posts
Rep Power: 4
 
Re: Beneteau Keel bolts

What is nice about Bob's design is that it spreads the load out over a wide area - if this Bene had comparative area of backing to support the keel, it would not so likely have ripped away the fiberglass so easily as it did. Those backing plates aren't any wider than the keel.
Lazerbrains is offline  
post #40 of 66 Old 08-29-2018
Administrator
 
Jeff_H's Avatar
 
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 8,628
Thanks: 28
Thanked 415 Times in 346 Posts
Rep Power: 10
     
Re: Beneteau Keel bolts

Quote:
Originally Posted by Lazerbrains View Post
I dunno what you mean, Jeff, by "designed in excess of standards." What I see (quite clearly) is a keel bolted to a fairly thin,flat area of fiberglass with no sump nor much reinforcement, and woefully small backing plates that do not look to be up to the task of distributing the load very well. In fact, it is no suprise to me that the fiberglass ripped away right at the edges of the backing plates. This simply looks like weak engineering and most boats I have inspected seem better engineered than this. The pictures tell the story.
Its not what I mean, since its not my conclusion that this boat was designed in excess of the current standards. It was the conclusion of a post construction analysis by the Wolfson Unit. In post #9 I posted links to Annex C&D which was the analysis done by the Wolfson Unit on the structural system on the 40.7's. Annex C & D speak for themselves. But that is what I was quoting when I made that statement. (You might take a look at that since its very well written and discusses many of the points in more detail than I am summarizing here.)

The one area that the report said was deficient under current standards was the keel bolts on that particular 40.7 built. The aft most centerline keel bolt was omitted on the boat in the report. (That is the bolt which failed on the subject boat of this thread as seen in the pictures of the top of the keel). Without that bolt, the bolts only achieved 95% of the current standard but still met the prior standard. This boat obviously had that last bolt present. But this was clearly not a case of a keel bolt failure (except that arguably may have been a bolt failure in the case of the aft most centerline bolt)>

In any event, whatever you think you see, the report in that link analyzed both the original engineering and construction of a 40.7 as it was actually built and concluded that the internal structure of the keel was 7.96 stronger than required under the current standards. And while those backing plates may seem small to you, they are larger than required by the standard and certainly larger than those that I have observed in many popular production boats, as well as on some higher end limited production boats. (i.e. Swan or on a similar sized Hallberg-Rassey)

To be clear, I am not saying that the structure was adequate for the loads that this boat encountered. Assuming that this keel was not in some way compromised by some other set of circumstands, obviously it wasn't.

But what I am saying is that what makes this model a little unique is the level of care that this model had in its design, building, and post construction analysis. My key point is that based on the post construction analysis by arguably the most advanced yacht structural engineering lab in the world, that the 40.7 and 36.7 were designed to be well in excess of the current design standards. So to the core of my point, if this boat has failed as badly as it has, what does this say about the majority of boats out there that were designed to barely meet this same standard, or worse yet, designed to barely meet some earlier standards which were less stringent than the current standard.

Quote:
Originally Posted by Lazerbrains View Post
What is nice about Bob's design is that it spreads the load out over a wide area - if this Bene had comparative area of backing to support the keel, it would not so likely have ripped away the fiberglass so easily as it did. Those backing plates aren't any wider than the keel.
But if you look at the photos of the internal structure of the 36.7 in the photo linked in Post 37, you can see that there is a very similar structure to the one shown for Francis Lee, only rendered in composite instead of steel and wood as was the structure on Francis Lee. 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. My bigger concern is that this type of structure is absent in the majority of boats out there, so if this one failed so dramatically, what does it say about the boats produced to a lesser standard of care.

Jeff


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay

Last edited by Jeff_H; 08-29-2018 at 03:34 PM.
Jeff_H is online now  
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
problems with keel bolts on beneteau michael white Introduce Yourself 8 09-25-2015 04:58 PM
Beneteau 345 keel bolts brummytezza Gear & Maintenance 6 01-06-2012 09:05 AM
keel bolts & 1999 Beneteau 381 fsp421 Beneteau 5 06-07-2009 11:43 PM
beneteau keel bolts shmangasarian Gear & Maintenance 0 10-19-2005 06:46 AM
Beneteau 361 Keel Bolts Greentree Gear & Maintenance 4 09-15-2005 06:32 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome