Hull Cracked / Deck Damaged - Beneteau 311

[wetass]

Doing just a quick google search, I found a survey listed online for a 311 where the surveyor noted the lack of knees and strengthening at the chain-plates - although as Watercaymen points out, I doubt with the headliner he could have really seen if there was additional fiberglass in that area: http://www.boatsurveyor.net/im_imag...urvey_Beneteau_Oceanis_311_sailing_vessel.pdf

Since it lasted until now, my guess is that it may have been a few things that all aligned at once (Speculation, but I can't help it):
- Maybe a little less laminate when built then called for, but who knows
- Maybe someone just before or after the sale "tuned" the rig and tightened the hell out of it
- Maybe he was sailing in conditions that the previous owner hadn't, even though it wasn't exactly heavy conditions.

 

[Beneteau 321]

I would like to add an other opinion.Is it possible the rig was not over tensioned rather it was loose.
If the rig was loose in a 3 ft sea way when the boat was tacked there woultd be shock loading on the shrouds caused by loose shrouds and the rough conditions .This shock would increase as the deck began to fail.
Further the pictures do not show if there were safety pins in the turnbuckles.If not even if the rig were tight to begin the trip the constant motion would gradually back off the shrouds in the turnbuckle.
A local boat(sailing in high winds waves) lost his mast this past season because safety pins were not installed and a upper shroud backed out of a turnbuckle completely

 

[anchorclanker]

regardless of loose shrouds, the boat should have much more substantial backing to the chain plates that extended into the hull. We still have no pictures of other boats of this model, but as most boats, even ones smaller than my old 222 have bulkheads in that area to tie the chain plates into, it would seem this boat was either built without additional support or it was removed.

One would also suspect the surveyor would have noted any loose shrouds. But once the deck started to let go, the stays got loose allowing slack, which would have exaggerated the issue.

Did Beneteau have a brain fart?

 

[wetass]

regardless of loose shrouds, the boat should have much more substantial backing to the chain plates that extended into the hull. We still have no pictures of other boats of this model, but as most boats, even ones smaller than my old 222 have bulkheads in that area to toe the chain plates into, it would seem this boat was either built without additional support or it was removed.

One would also suspect the surveyor would have noted any loose shrouds.

From what Watercayman said earlier about his own 311 and the survey of another 311 I posted above where the surveyor noted this design, I think this is the way they are built - without knees, direct bulkhead attachment, or some other system to transfer the loads to the hull (save the toe-rail to spread the load along the rail and maybe a bit more glass in that area). Don't recall ever seeing a boat designed this way and this is probably why :cry:. I have seen boats without traditional chainplates that used U bolts or pad eyes to terminate the shrouds, but they went through a steel backing plate or angle iron mounted under the deck that was then tied in some way to the topsides - Cape Dory's used this design (rebar rods welded to the steel backing plate that were then glassed to the topsides) .

But, having said that, given what Watercayman noted about the # of these boats out there and in Charter, this does not seem to be a big problem. It sounds like for how they are generally used, it must work OK. Personally, I would shy away from a boat with this design, but if I owned one already I wouldn't run out and sell it right away thinking it was about to fall apart. I would consider reinforcing it though.

Hopefully insurance will help the OP out - I can only imagine the horror of finding something like that on a brand new to you boat after shelling out good money. In the end, hopefully they are able to repair it and my guess is that if they are able to (anything on a boat can be fixed with enough $) it will be stronger then designed.

 

[sailandrelax]

Looks like my 2012 Beneteau 31 is the same, which means B has been making them this way for at least 16 years (MY 1998 - MY 2013) without any issues till this one. Probably the same failing rate as any other system out there.

We chartered a 311 last fall in BVI and trust me, we did not go lightly on that boat. 25-30 knots of wind on two days with more than a few hard jibes.

I am not at all worried about the design. I am wondering about the conditions that could cause this on any boat though, and plan to check my rigging, even though my boat is relatively new.

 

[Jackdaw]

I've had some more thoughts about this...

It occurred to me that the failure point was not the A) chain plate pulling up thru the deck, or B) the deck/hull joint separating. The actual HULL broke, which should have been the strongest of those three potental failure points.

This leads me to believe that this PARTICULAR boat had some errors made in its hull layup schedule... Like on my 260 I suspect that the glass in this area of the hull below the chainplates should have been much thicker, and much more resistant to failing under load. I guess that they may have missed that or went light. That's where I would look first.

We also have to remember that this boat was designed by Finot-Conq, one of the most prestigious design houses in the world. They know what they are doing, know how to calculate stress loads. Unlike boats from the 70s or 80s that are overbuilt because the loads were unknown, they computer simulate all potential loads on the rig and hull. To suggest that this was just 'missed' in the design or 'cheap' is ridiculous. Something was wrong with this boat.

This only thing I can't sus is 'why now'. It seems more than just a coincidence that it failed on a new owners shakedown cruise.

 

[DougM]

I have a B323 and it is definitely built the same way. I have seen no evidence of any unusual stress in the area where the shrouds anchor to the deck. There are not even any spider cracks in the fiberglass in that area which would imdicate at least some stress. As I recall, the backstays are anchored in the same manner. Any sudden shock loading such as a hard jibe would seem to affect that area as well.

This is conjecture, but is it possible that there was some hull damage in the shroud anchorage area caused by colliding with another boat or an unusually hard docking? Was the boat lifted by a crane or a travel lift with the slings in the wrong place (not too likely because of the location ofthe keel)?

I agree with the observation that anchoring the attachment points through the toerail does a good job of spreading the load horizontally along the deck.It would seem that it would take a considerable amount of rig overtensioning to cause that amount of deformation. I would be curious to see what the attachment points to the mast looked like. Being careful with tensioning is important. The use of a Loos gauge and just going by the recommended numbers for the shroud diameter not only helps to get the rig balanced, but would certainly would prevent over tensioning.

I would be interested in what Beneteau would have to say about this particular boat. It would seem that this is an unusual case based on the number of boats out there with similar design, especially with the number in charter fleets which probably encounter much more abuse from presumably less experienced sailors and possible lack of maintenance.

The next question would be how to develop a preventive engineering retrofit to insure that this could not happen. For example, an under deck bracket through which the anchorages could be bolted, with tension rods anchored to the hull substructure? Just a passing thought....

 

[sandpiper10471]

Seems to be consensus that the photos show the original engineering. I suspect the area was compromised by too much squeezing by a travel lift and was manifested sailing. Over tensioning the rig should jeopardize the mast, not the chainplate area.

 

[anchorclanker]

I can say matter of factly that I am not an engineer, no degrees or anything. But I can also say that I have done a lot of study into various designs to understand why things are built particular ways, the understanding of the "parts" as it were.

Gussets and knees are used to give strength to parts that join at opposing angles. We see them in trusses, engine frames, race car cages. Some refer to it as triangulation. Trusses are used to give strength to large flat surfaces. Bulkheads are used to make a tube stronger in cross section, in effect a continuous gusset around the inside of the tube (sailboat in this instance) that also acts as a truss.

What appears the engineers did here, was use the "C" channel shape of the toe rail to act as a truss. This was then beefed up by a heavy metal toe rail to carry the load into the hull/gunwale. In other boats the chainplate is backed underneath by heavy plate to act as a truss, to extend the load outward in all directions into the surrounding area. But in addition, the boats often have a bulkhead in the same area, and tie the chainplate to that as well.

In still others, they do as Maine Sail showed. They build heavy knees into the hull at the gunwale, and tie the deck and chain plates to those knees. I would assume Beneteau had engineering showing their design was strong enough, but only if built with enough glass and resin, rivets to the hull/deck interface, etc... If there were any quality control problems, the designed for strength would be compromised. As most buyers are ICW cruisers, perhaps they built these weaker? Cheaper? Wanted a different look of spaciousness and thought they could get away with it?

The question is, has this happened to any other boats of this model? Not everyone is on forums, and not everyone is so quick to divulge information. Regardless, the boat should have knees installed to the gunwales with carry throughs to the chain plates such as Maine Sail pictured earlier. Then I would buy a different boat. That last one is one reason people might not divulge information. Hard to sell a boat with a bad reputation.

 

[Jackdaw]

Clanker,

I'm pretty sure that the toe rail doe not add nearly as much strength to the design as you might think. The structure looks like the picture below. The load from the rig tension comes down the stay and into the fitting/chainplate, where the load is spread outward. I'm sure they looked at this pretty hard in FE modeling. The load ends up going DOWN the hull, which makes the joint by the fitting key. This has to be designed to take the load. My GUESS is that in the design this was supposed to be built-up with extra glass near the fitting, but perhaps in this boat (by a mistake in the layup) was not.

Why does Maine's CS have those huge knees? Simple, his plates are in the middle of his side deck. (green spot on diagram) Loads from the stay would massively deform the deck before the load was transferred to the hull.

 

[Ron20324]

I don't know why people belly-ache about ONE boat that crumbled to to no specific cause. Sure, blame the naval architect that designed the boat, or the crummy (?) factory that screwed up the laminate. The thing broke on the first sail, so it may be that the problem had already happened, but was masked by caulk or paint. My B323 is built to a Lloyds rating of, IIRC, a class "C", but I do remember it is built to 13-foot seas capability. Maybe you'll recall the race boat that just cracked in half like an egg shell. Crummy engineering? But don't dump on Beneteaus as being poorly designed just because it's not made the way YOU would do it. Otherwise, if you don't like it, don't buy it. If it passed Lloyd's it says something.

 

[anchorclanker]

That construction detail looks much weaker than I would have imagined from a boat of that caliber.

 

[Jackdaw]

That construction detail looks much weaker than I would have imagined from a boat of that caliber.

Well you said it, you're not an engineer! ;^)

I know people the flat out refuse to sail on boats without back-stays, even thought this style of rig geometry is sound and well founded in design principals.

The simple truth is that Finot designed this style of shroud attachment 15 years ago and Beneteau has been using it ever since, in several models. And both companies are still in business, unlike 95% of the boats discussed here on the forum. If there was a problem, they would have changed the design. As Ron points out, one known failure (under mysterious circumstances) out of over 1000 hulls. The original poster need to sort our what happened to HIS boat and WHY.

Another thing, lightness is its own reward in sailboats. Overbuilding something to withstand forces it will never see is a waste of time, money, and boat speed.

 

[anchorclanker]

People with no engineering degrees at all have built boats that sailed all over the world without any issue. Others with astounding numbers of fancy degrees from the best schools have built things that couldnt cross a small pond. The Vasa comes to mind as an engineering disaster, as does the Tacoma Narrows Bridge, The Kansas City Hyatt walkway collapse, the DC-10, and other marvels.

There is a reason most boats have bulkheads and/or knees in that area, and it doesn't take a genius with a piece of paper on the wall to understand why.

 

[Jackdaw]

People with no engineering degrees at all have built boats that sailed all over the world without any issue. Others with astounding numbers of fancy degrees from the best schools have built things that couldnt cross a small pond. The Vasa comes to mind as an engineering disaster, as does the Tacoma Narrows Bridge, The Kansas City Hyatt walkway collapse, the DC-10, and other marvels.

I don't disagree with anything you say here. But I don't see your point.

With respect, you should look at some NEW boat designs. Like from this century. You will find a lot of them with shrouds that run to the hull, without bulkhead or knees. Really.

I sailed for 7 days on one of these last week. Pogo 12.50, designed in 2011. Shrouds under 2.2 TONS of static load. Brought to the hull. Pretty sure it was not luck or magic that held the rig up. Just good sound engineering.

 

[Maine Sail]

Quite a huge contrast in the German Frers or even Farr designed First series chain plates and the one on that 311..

 

[Jackdaw]

Quite a huge contrast in the German Frers or even Farr designed First series chain plates and the one on that 311..

OK, I'll bite! ;^)

Are you say different = under-engineered? Let's some back to that.

Let looks at a Friers First, a 1981 First 42. Great boat for its time. It weights 18000 lbs, and as 8000 is ballast, the hull and rig weigh 10000 pounds. Thats a lot. Its simply overbuilt. And it requires a crew of 8 to handle downwind, and its a cranky wobbly beast. Been on one, I know.

That Pogo 12.50 from last week? Flat out better engineered. Its THIRTY years newer! Built to modern engineering standards that simply understand loads and modern materials. I simply do not agree that things must be heavy to be good. And thankfully neither do modern boat designer. If that where true we would all be driving Trans Ams. The Pogo (at 41 feet) displaces 12000 pounds. subtracts off the keel, and the hull and rig weigh 5040 pounds. HALF AS MUCH. Now you have a 40 footer that can plane with the breeze in the teens. And I tell you, I would much rather go across the Atlantic in the Pogo. And two people can sail it downwind.

People ask why no one is buying new boats. Maybe its because they think that all perform like boats designed in the 70s and 80s.

That was over 30 years ago. The world has changed.

Go look at the European BOTY winners and runners up over the last several years. Pogo. Seascape27. J/70. B-One. Light boats that are fast and easy to sail. Someones on to something.

 

[wetass]

I might be wrong, but I think the Pogo 40 has a traditional chainplate where it ties into the hull topsides. Your right that it doesn't have knees, but thats because the chainplates tie into the outside of the topsides and not into the deck.

 

[Jackdaw]

I might be wrong, but I think the Pogo 40 has a traditional chainplate where it ties into the hull topsides. Your right that it doesn't have knees, but thats because the chainplates tie into the outside of the topsides and not into the deck.

Re the Pogo 40s (there are at least three flavors), it depends. The Pogo 12.50 does not have traditional chain-plates. It does have a structure (part of the hull) to tie the gunwale loads to the grid. And to your second point, that was MY point. Its similar to the 311, shrouds to the hull; just smaller loads.

 

[Lee Hadjiosif]

Why doesn't the original poster, Raul, post an update of what he found and what he's doing about it since there's so much interest in the subject? ...unless he's under his lawyer's advice to keep quiet.
S/V Adagio