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Old 18-12-2015, 11:05   #706
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Re: Oyster Problems?

I have been involved in two claims against well known production builders. One case was clearly a production issue that was irreparable in that it would cost more than the value of this brand new boat to fix it. The other case was a powerboat that came close to sinking on several occasions and was clearly a case of bad design.

In both instances after working on the issues for months, both owners called me out of the blue and said the matter had been settled and I need go no further .......... I can only speculate as to what caused them to call me off and that speculation would be unflattering to those two builders.
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Old 18-12-2015, 11:39   #707
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Re: Oyster Problems?

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Originally Posted by Van Der Beek View Post
If this is true it's not only disturbing but we'll see more keels falling off in a not to distant future. Buying an older boat and doing a complete overhaul and refit would be the best option in terms of quality and engineering.

Ninja edit.
Most of us like to look at sailboats despite being happy with our current boats and I'm no different. I found this on YouTube when checking out a Danish boat builder. I don't know enough to speak to this but perhaps someone else could comment? It looks good from what I can tell.



4:20 marker
That X35 is one of the few using a steel or CF keel structure, I applaud that initiative, sad others don't follow something similar...
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Old 18-12-2015, 11:49   #708
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Re: Oyster Problems?

They are really well made, in fact... Watertight bulkheads , wow.....


http://www.google.es/url?sa=t&rct=j&...EsSMirRTpcAdWA
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Old 18-12-2015, 11:58   #709
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Re: Oyster Problems?

And Arcona yachts also use a steel keel grid system, SWEDEN Q.
http://www.google.es/url?sa=t&rct=j&...xk-6gLB0wvRkdA
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Old 18-12-2015, 11:58   #710
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Re: Oyster Problems?

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Originally Posted by leftbrainstuff View Post
+1.

Here's my engineering root cause analysis. (from my arm chair)

Matrix detachment describes a design choice typically made because of a manufacturing benefit. It introduces a latent defect.

The interface is fundamentally a joint. (Think gasket joint) Failure due to peel is the primary failure mode.

Why do we use a gasket joint? To allow us to seperate components. How do we seperate a bonded gasket joint? By applying a tensile force that is non linear. This is peeling.

What happens during grounding? We apply a peeling force to the keel / interface. Even worse we apply an impact force to a non flexible gasket.

Pretty stupid design choice. If a 2nd year engineering student proposed this design he, or she, would get an F. (Fail)

My real concern is why we let the standards agencies classify such a design as ocean rated. It's not only stupid (this is structural engineering 101) it smacks of incompetence.

In the aviation industry log books, maintenance and reporting of clearly defined events is mandatory. It's not perfect but it is a proven method of managing component life and latent defects. Of course rigorous non destructive and destructive testing is needed.

I sleep just fine on my Liberty 458 with a fully encapsulated keel.
In fact on the Oyster you have an encapsulated stub...and it was the stub that failed due to a probable weakness on the vertical part of the keel support structure.
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Old 18-12-2015, 12:00   #711
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Re: Oyster Problems?

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In fact on the Oyster you have an encapsulated stub...and it was the stub that failed due to a probable weakness on the vertical part of the keel support structure.
What's encapsulated ? looks like a plain old GRP stub to me.
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Old 18-12-2015, 12:03   #712
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Re: Oyster Problems?

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Originally Posted by neilpride View Post
And Arcona yachts also use a steel keel grid system, SWEDEN Q.
http://www.google.es/url?sa=t&rct=j&...xk-6gLB0wvRkdA
As I have told you already and you seem to be discovering now, several brands use a carbon, steel or reinforced composite structure as a grid to distribute the efforts of the keel and shrouds by the hull.
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Old 18-12-2015, 12:07   #713
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Re: Oyster Problems?

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Originally Posted by Polux View Post
As I have told you already and you seem to be discovering now, several brands use a carbon, steel or reinforced composite structure as a grid to distribute the efforts of the keel and shrouds by the hull.
You must keep dreaming dude, last year I got a X yacht in the rigging shop for a riggig tune. In my dock....
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Old 18-12-2015, 13:04   #714
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Re: Oyster Problems?

Let's look at what is comparable to Oysters. Some hear expressed the idea that recent Oysters are producing too light boats and that they should go back building heavier boats with old building techniques, like encapsulated keels and all that jazz. So lets compare it to Amel to see if they are really making light boats by modern standards.

The recent Oyster 625 as a LWL of 17.24m, a beam of 5.44m and a light weight of 33 500kg.

The Amel 66 as a LWL of 17.21m, a beam of 5.60m and a light weight of 34 100 kg.

Very similar ideed. Maybe Amel is also making too light boats, at least for some


Let's look at the keel structure that is a strange one, that certainly have been proved on older models, one where a wood grid and bulkheads play a major role. The keel is not properly encapsulated but surrounded by polyester and it is fixed to the hull by steel bolts.

The structure that it is what supports lateral efforts don't seem to be as strong as much would expect even if I am sure it is well designed and it is up to the job.


The structure in this case is not pre-built but assembled on the local.
The boat structure and bulkhead is made of Omega mousse polyurethane and plywood stratified to the hull.

Very difficult to find information regarding how Amels are built. Not a word on the shipyard site and this few elements are not enough to understand really how the keel is fixed and what it will look like the complete keel structure.

The objective of posting this is not showing that the Amel are built in a light way. They are certainly not, only to point that modern structures, without having the data or knowledge to understand them, may look flimsy to many when obviously are well up to the task.
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Old 18-12-2015, 13:12   #715
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Re: Oyster Problems?

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Originally Posted by Polux View Post
A final point: In what regards modern sailboats it does not make sense to put on the same level boats that cost 2 or 3 times more than others. It is obvious that it is expected a much better quality building from brands that make much more expensive boats and it is rightly assumed that the better quality does not regard only a better quality interior but also a better built quality.
I think where some may differ from you, Polux, centers around which components you have to pay extra for in a premium brand. If it's fancy interiors, components, etc., then that's fine. But I don't think those that can only afford the lower priced production boats should have to sacrifice build quality when it comes to critical structural components. You are certainly buying more luxury items with a Mercedes and it may in fact be an overall safer car, but that doesn't mean you should also expect your Kia not to come with seat belts or airbags, or that the wheels may fall off.

I would find your position on the very low incidence of failures more persuasive IF:

1. The vast majority of leisure boats of all stripes weren't rarely used, and the ones that were used weren't rarely stressed;

2. There wasn't what I believe is probably consistent underreporting of the type of serious failures we're discussing. Sure, if it affects an entire model line or causes a dramatic sinking and/or rescue. Otherwise, such failures are often dealt with at the nearest available yard and would otherwise not necessarily be publicized unless the owner or yard tech happens to be on the forums. I agree with your point that this doesn't also necessarily prove a higher incidence, but when we're talking structural problems it isn't unreasonable to surmise that similar boats may also be affected;

3. We also don't have any accurate way to estimate the corollary, namely how many of the Bene First boats you mentioned who are competing in the Sydney-Hobart this year (just to take one example) have taken the preemptive & cautionary measures Bene recommended after the CR incident, namely dropping keels, inspections, repairing as needed (if possible);

4. Purely anecdotal for sure, but I'm often reminded of the incident Dockhead recounts of hitting an uncharted rock hard and at speed, in a boat which enjoys a good reputation for structural strength among other things. I believe he said he subsequently had it properly surveyed and all was well. I'm not sure anyone is suggesting not having your boat inspected after such an incident, but rather that it be built strongly enough to get you home. The problem is, if you're out cruising, home or the nearest suitable facility may be a long ways off, and all of the boats we are generally discussing have the Cat A "All Oceans" rating; and,

5. I'm not sure the hard vs. soft grounding line of reasoning gets us anywhere. First off, how do you define? Second, unless you're the boat's original owner, how do you know? Third, there have been keel & rudder problems reported by Minaret & others that were purportedly due solely to soft groundings, and CR's MAIB report concluded that mere pounding in a seaway may have also played a role. Are you also required to survey your boat after incidents such as those, or should that be factored in as reasonably foreseeable events when you purchase a boat designed & marketed for cruising?
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Old 18-12-2015, 13:39   #716
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Re: Oyster Problems?

Amel use for their keel something really diferent in all the aspects, they are bolted to a stub , the stub its really thick compared to some others brands, and deep, most amels keels use lots of bolts, in a supermaramu the number is 22 keel bolts , wow.... the water tank is made on top of the keel bolts , its watertight and glassed to the hull, I mean its integral with the hull , kinda of a second stub on top of the keel.. I never see one with any kind of keel problem by the way , they are simple following what they do in the past, strong boats....
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Old 18-12-2015, 16:25   #717
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Re: Oyster Problems?

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Keels that must be inspected and professionally repaired after a grounding is my "deal breaker". I steadfastly hold to the view that the keel should never fall off. If there is a collision so severe that the entire boat breaks apart then I would expect the keel to sink holding tenaciously onto its attachment and a majority of the remaining hull. I never want to see photos like those of PS III or CR ever again...ever.
While no vessel's structure can realistically be guaranteed 100% unbreakable, I agree that it should be unacceptable that any yacht is so lightly constructed that an inspection must automatically follow any grounding, no matter how minimal.

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One way we can all help the yachting industry get its collective head screwed on straight is to clearly articulate the requirements that are "deal breakers" for cruising yachts.
Fair enough, in theory. However, most current production boats are purchased by charter companies or relative novices. As long as the number sold to knowledgeable sailors is pretty insignificant, the latter's preferences and requirements will continue to count for little.

If things are going to change, I suspect that market forces will not accomplish this and that legislation (e.g., changes to the RCD) will be necessary.
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Old 18-12-2015, 16:56   #718
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Re: Oyster Problems?

Most production boats are purchased by charter companies. That sounds wrong.
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Old 18-12-2015, 17:15   #719
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Re: Oyster Problems?

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I bet pretty much all boats build now days have been designed by a naval architect, including all the boats that people saying are build to minimum (which means that they are built to handle the designed stress).

What we never really hear about is input from actual builders that forums are always saying are cutting corners etc .

I bet if we really had a break down of the costs of boat construction we would find that the cost savings of some extra fiberglass isn't much in the big picture. And from that we would also learn is that builders don't under-build to save costs as much as they build to the design stress of the boat.

I bet we would also find that the cost of building a a same size hull is about the same for all builders once it adjusted for volume discounts.
I had always thought that the single biggest cost in mfg. a more traditionally-built boat were the hull & scantlings, and that the primary reason modern boats could be built & sold for so much less money was the technology that reduced the cost (mostly labor) of those same components. I'm not sure how this breaks down with the use of thinner laminates, i.e. less fiberglass. All I know is that one side calls it cheap construction, whereas the other calls it less expensive but equally fit for purpose and lighter/higher performance. For cruising boats anyway, the difference becomes more stark when docks are hit, hulls are grounded, etc.

It would be interesting to have a better sense of just how much cost is saved on a modern production boat by using a thinner laminate.
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Old 18-12-2015, 17:17   #720
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Re: Oyster Problems?

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Most production boats are purchased by charter companies. That sounds wrong.
Polux said awhile back that it was more like only 25%, i.e. less than what may be commonly thought. Not sure myself.
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