Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-12-2015, 00:20   #676
Registered User
 
Muckle Flugga's Avatar

Join Date: Apr 2008
Location: Aboard the Ocean wave
Boat: 55' sloop.
Posts: 1,426
Re: Oyster Problems?

Quote:
Originally Posted by neilpride View Post
But but , I don't think its a real thread drift, if you see the root of the point, a big boat loosing part of the hull , some way you reach the other point, the actual weakness in some brands...
I don't really see it as thread drift either. The Polina Star III evidence suggests that one of the few remaining true great boatbuilders of quality, is trending towards the "just enough" philosophy, rather than the "bombproof, seaworthy, and robust, with strength to spare" philosophy. This is, it would seem, industry wide.
__________________

__________________
‘Structural engineering is the art of modeling materials we do not wholly understand into shapes we cannot precisely analyse as to withstand forces we cannot properly assess in such a way that the public at large has no reason to suspect the extent of our ignorance.’
Muckle Flugga is offline   Reply With Quote
Old 18-12-2015, 03:30   #677
Moderator
 
JPA Cate's Avatar

Join Date: Nov 2011
Location: aboard, cruising in Australia
Boat: Sayer 46' Solent rig sloop
Posts: 10,670
Re: Oyster Problems?

., ...and that, perhaps, is why the mysterious Polux who wishes to disclose nothing about his work, but who seems keen on selling modern boats, publishes lengthy treatises which seem short to meat, when regarding inadequate boats. Sorry, Polux, don't really want to malign you, but truly, IMO, any production boat not intended for racing, should be able to be lifted out in the slings, and then set on the timbers underneath the keel, for a normal bottom job, without the hull deflecting, and to me, arguring otherwise is a grievous fault.

Ann
__________________

__________________
Ann, with Jim, aboard US s/v Insatiable II, in Oz, very long term cruisers
JPA Cate is offline   Reply With Quote
Old 18-12-2015, 03:57   #678
Registered User
 
leftbrainstuff's Avatar

Join Date: May 2011
Location: San Francisco and Australia
Boat: Liberty 458
Posts: 1,978
Re: Oyster Problems?

Quote:
Originally Posted by Cap Erict3 View Post
The potential fragility seems inherent in the design of many fin keels. Certainly hull strength at the keels attachment point should a priority but what about beyond that?






I sleep better on the hook
+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.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app
__________________
leftbrainstuff is offline   Reply With Quote
Old 18-12-2015, 04:10   #679
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: Oyster Problems?

No idea how Lloyds put the ok in this one, i mean even my old 1978 CSY , by the way rated by Lloyds in those years, cutting samples from hull, deck and even the cabin roof are tested to the extreme , something is really wrong with those turkeys computer controlled resin infusion devices , i mean could be a wrong mix ratio or who know, a toasted chip during infusion. LoL
__________________
neilpride is offline   Reply With Quote
Old 18-12-2015, 04:19   #680
Registered User
 
leftbrainstuff's Avatar

Join Date: May 2011
Location: San Francisco and Australia
Boat: Liberty 458
Posts: 1,978
Re: Oyster Problems?

Quote:
Originally Posted by Exile View Post
I'm not sure I'm following your logic. Like the one Oyster, only one Bene 55 had a problem that has been reported. The fact that Oyster called in other boats of the same model for reinforcing and Bene did not for other 55's doesn't necessarily mean that the Bene had an issue isolated to one boat. I'm not familiar with bow thruster construction, but if the rumors are true about water ingress from that area then wouldn't that be some sort of breach of the hull surrounding the thruster itself? Sure, it could have been a mfg. defect that only affected one boat, but there could also be some weakness in that area that has yet to manifest on other 55's, or more likely just hasn't been reported. The one boat theory also makes less sense to me from the largest mass producer in the world, even if the 55 is obviously made in smaller numbers.

I also don't follow your distinction between a "defect in building" vs. a "design problem connected with a defective production method." I understand the distinction in the abstract, just not why it's relevant to the several boats being discussed here. None of them are one-off custom builds, after all, so whether the fault lies with the design dept. or is derived from the factory floor hardly seems relevant, at least to this discussion.

Finally, since when are accidents "registered" on new boats? The little we've heard about the 55 was due to the publicity of it being on its way to a boat show, and from the CG rescue. Nothing from Beneteau itself as far as I'm aware. How would we necessarily know if other problems have developed on 55's in more benign, less dramatic circumstances, like when the boat is just sitting at its slip?
A design defect and manufacturing defect are fundamentally different in terms of detectability.

Quality assurance (QA) relates to design. Quality control (QC) relates to production.

But both can introduce a latent defect. Detectability of many build defects is poor when QC is absent or not trustworthy. If QA is lacking then detectabilty of a design defect can also be poor.

A design defect relates to the type. A build defect relates to 1 or more units of a type.

Bolted keels are clearly a design defect. They fail even a simple engineering analysis in terms of durability and survivability.

In the boats we're talking about the choice was made, not to benefit the end user, but to benefit the manufacturer.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app
__________________
leftbrainstuff is offline   Reply With Quote
Old 18-12-2015, 04:25   #681
Registered User

Join Date: Mar 2011
Location: Caribbean
Boat: Oyster 66
Posts: 973
Re: Oyster Problems?

Quote:
Originally Posted by Ann T. Cate View Post
., ...and that, perhaps, is why the mysterious Polux who wishes to disclose nothing about his work, but who seems keen on selling modern boats, publishes lengthy treatises which seem short to meat, when regarding inadequate boats. Sorry, Polux, don't really want to malign you, but truly, IMO, any production boat not intended for racing, should be able to be lifted out in the slings, and then set on the timbers underneath the keel, for a normal bottom job, without the hull deflecting, and to me, arguring otherwise is a grievous fault.

Ann
Polux has said elsewhere a number of times that he works as an architect. That seems to perfectly qualify him to have considered views on design issues especially. I also don't find any reason to think his motives are not sincere as was suggested by others. Not that I agree with all his views, just the opposite on questions of the adequacy of construction of boats.
__________________
poiu is offline   Reply With Quote
Old 18-12-2015, 04:32   #682
Registered User
 
Polux's Avatar

Join Date: Nov 2011
Location: Portugal/Med
Boat: Comet 41s
Posts: 5,761
Re: Oyster Problems?

Quote:
Originally Posted by Ann T. Cate View Post
., ...and that, perhaps, is why the mysterious Polux who wishes to disclose nothing about his work, but who seems keen on selling modern boats, publishes lengthy treatises which seem short to meat, when regarding inadequate boats. Sorry, Polux, don't really want to malign you, but truly, IMO, any production boat not intended for racing, should be able to be lifted out in the slings, and then set on the timbers underneath the keel, for a normal bottom job, without the hull deflecting, and to me, arguring otherwise is a grievous fault.

Ann
What are you talking about? What has my work to do with that except that in what regards to be an Architect with experience in structures and with a long interest in recent sailboat allows probably a better understanding than most regarding how they work on a structural point of view.

Did I said the flexing on a hull is normal or adequate? It depends and I don't know of what they are talking about regarding boats being permanently on slings. I have been on many shipyards and i never saw production boats or other boats resting permanently on slings. While a normal bottom job is done I never saw boats in slings except if the boat is to be put on the water shortly after that and for convenience reasons.

Probably some of the biggest shipyards for having boats on the hard are on Greece, go to Preveza, to Ionian marina or Cleopatra marina, or Mesalonghi marina (been on both last year). Go there and you will see many hundreds of recent production boats on the hard for all winter and not a single one on slings.

If you think that in what regards modern boats, an in what regards the knowledge of how they are built, the opinion of someone that think and says that a modern Beneteau is built the same way as a Bavaria, is a more valid one than mine, you are entitled to.

But if you care to know something about it, some research of your part will show otherwise, it will show that Beneteau hulls and structure is built very differently than the ones of Bavaria.

Beneteau, in what regards the hull uses an exclusive method (used by Jeanneau too), it uses a solid laminate on all hull and an interior "contre moule" that is bonded to the hull. You will see that Bavaria uses a solid laminate on the immersed part of the hull and cored hulls over the water line.

Regarding boat structure you will see that Beneteau uses an integral matrix (that covers integrally almost all bottom of the boat - you cannot see the hull), a sort of reinforced "contre moule", bonded to the hull while Bavaria uses a structural grid that is laminated (glassed) to the hull.

While on Beneteau is difficult to know if the boat structure (or the contre moule) remains bonded or not, on the Bavaria it is a grid and you see the hull and the points of contact of the grid with the hull as well as the tabbing being easy to see if everything continues properly glassed.

Yes very similar build, very knowledgeable

As i said already this thread is about Oyster s with problems and I don't see why you are contributing to continue to put it out of track. The amount of noise on this thread that as nothing to do with the subject is already much more than the valuable information about Oysters with problems.

I would suggest, that, for the thread to be valuable as information regarding the subject, that the ones that want to discuss other matters, like the differences in built between Bavarias and Beneteaus or the evolution in what regards Bavaria's, or mass production boats, do so on existing on threads about the subjects or open new threads about it.

I don't understand how moderation allows a thread with valuable information about an important issue goes widely out of track submerging the valuable information on the subject with all kind of out of subject noise.

As I have already said, i will not contribute for the thread drift.
Polux is online now   Reply With Quote
Old 18-12-2015, 04:37   #683
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: Oyster Problems?

What have in common a Architect and a Naval engineer?Definitely when someone defend no sense like a bad weak keel joint design then is kinda chopped matt logic.
__________________
neilpride is offline   Reply With Quote
Old 18-12-2015, 04:46   #684
Registered User
 
Polux's Avatar

Join Date: Nov 2011
Location: Portugal/Med
Boat: Comet 41s
Posts: 5,761
Re: Oyster Problems?

Quote:
Originally Posted by neilpride View Post
But but , I don't think its a real thread drift, if you see the root of the point, a big boat loosing part of the hull , some way you reach the other point, the actual weakness in some brands...
So after all it seems that the quality of built of Oyster is the same as Bavaria and other production boats?

I don't think the matters are related. Oyster is a very expensive brand and it is normal to associate that difference in price, that is more than double, to a much better build quality.

The catastrophic failure on a brand were that failure was not expected to be possible is what is in discussion on this thread as well as the implications that can have (or not) on all recent boats built by Oyster.

Those implications depend on the assessment of why that happened on this particular case and I would say that what we have observed till know it is not reassuring regarding this to be an isolated case, I mean the hull thickness at the bottom and the hull thickness on the grid.
Polux is online now   Reply With Quote
Old 18-12-2015, 04:49   #685
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: Oyster Problems?

Well if you ask me, i can feel safer in a Bavaria than in a Oyster 825, after see that Pixie Dixie construction.
__________________
neilpride is offline   Reply With Quote
Old 18-12-2015, 04:54   #686
Marine Service Provider
 
boatpoker's Avatar

Join Date: Nov 2008
Location: Toronto, Ontario or Bahamas
Boat: Benford 38 Fantail Cruiser
Posts: 2,593
Re: Oyster Problems?

The first time I looked at Polux' profile it said "retired art teacher" more recently it says "architect/retired art teacher".
__________________
That hysterical laughter you hear as you sail a way in your "new" boat ..... is the seller.
boatpoker is offline   Reply With Quote
Old 18-12-2015, 05:00   #687
Registered User

Join Date: Apr 2006
Posts: 4,413
Re: Oyster Problems?

Quote:
Originally Posted by Polux View Post

....

Did I said the flexing on a hull is normal or adequate? It depends and I don't know of what they are talking about regarding boats being permanently on slings. I have been on many shipyards and i never saw production boats or other boats resting permanently on slings. While a normal bottom job is done I never saw boats in slings except if the boat is to be put on the water shortly after that and for convenience reasons.

Probably some of the biggest shipyards for having boats on the hard are on Greece, go to Preveza, to Ionian marina or Cleopatra marina, or Mesalonghi marina (been on both last year). Go there and you will see many hundreds of recent production boats on the hard for all winter and not a single one on slings.

If you think that in what regards modern boats, an in what regards the knowledge of how they are built, the opinion of someone that think and says that a modern Beneteau is built the same way as a Bavaria, is a more valid one than mine, you are entitled to.
....

As I have already said, i will not contribute for the thread drift.
This last post sounds like "thread drift" to me.

Building architects (at least in the USA - I am a NYC licensed on for 35yrs ) and structural engineers perform very different services. Obviously they need to understand what the other does.

Naval architects... as far as I know are more like structural engineers... structure being their primary function. I don't think the typical land architect is competent to or versed in the ins and outs of structural work for boats.

Sailing yachts are approached more like unique one off designs... something not seen in the aviation industry (I believe). It seems economically and time wise not possible to do thorough testing.. destructive and so forth because of the sales volume. My sense is that the design and construction "processes" evolve, building on tried and true...

In come the bean counters looking for ways to make the product more profitable and that usually means less material with the attending improved performance related to less displacement. How cool! We can make a better performing boat and make more money by using less material.... and more advanced stronger ones.

What doesn't change are the natural forces... And what also doesn't change is that boats are COMPOSITES of several structural elements which have to be joined together and work as a composite. Now you have the issue of joints and integrity of composite structures. If the composite's elements cannot be made composite without compromising the composite ... fine. But this seems to get into the whole issue of joints and structural bonding and so forth... with a composite only being as strong as its weakest link.

My sense is that the is more complex and expensive than what the manufactures and the designers are capable or prepared to deal with. What is out the window is testing and certification and the whole process seems too unregulated and ad hoc.... relying on reputation... rather than testing and proving.

Hubris and Greed... a deadly combination.
__________________
Sandero is offline   Reply With Quote
Old 18-12-2015, 05:05   #688
Registered User
 
transmitterdan's Avatar

Join Date: Oct 2011
Boat: Valiant 42
Posts: 4,019
Re: Oyster Problems?

Pollux,

Why these issues of different builders are related is the yacht industry across higher volume lower cost right to low volume high cost builders seem to be taking advantage of the cost savings afforded by modern design methods. Modern design allows detailed analysis of small features to compute stresses and strains. By the "lean method" the unneeded parts are trimmed away or moved in the design phase until the structure is just enough to satisfy the forces. This results in a lighter, faster and less expensive boat.

The problem is that across the spectrum of builders from lower to higher cost some builders seem to be misapplying the "lean method". They are forgetting (intentionally or otherwise) that the material they use and the environment of use have significant variables. It seems clear that there is a lack of appreciation for the uncertainty that surely exists with yacht design. But modern design methods (which are in fact more than 200 years old) have provisions for dealing with uncertainty and these designers and builders are either not using them or not applying them correctly.

Further, there is among the posters of this thread a disturbing division. There are those who say that margins of safety should be employed in cruising yacht design such that the keel never ever will fall off. Then there is a group who say its ok right now because only a very few fall off. And we should accept it because of the net benefits (lower cost, faster, lighter, etc.). To me that's a bright line difference of opinion. Which opinion is right matters greatly. If future readers of this thread are incapable of figuring that out then I have just cleared it up for them.

You're welcome...
__________________
transmitterdan is offline   Reply With Quote
Old 18-12-2015, 05:07   #689
Registered User
 
Polux's Avatar

Join Date: Nov 2011
Location: Portugal/Med
Boat: Comet 41s
Posts: 5,761
Re: Oyster Problems?

Quote:
Originally Posted by leftbrainstuff View Post
A design defect and manufacturing defect are fundamentally different in terms of detectability.

Quality assurance (QA) relates to design. Quality control (QC) relates to production.

But both can introduce a latent defect. Detectability of many build defects is poor when QC is absent or not trustworthy. If QA is lacking then detectabilty of a design defect can also be poor.

A design defect relates to the type. A build defect relates to 1 or more units of a type.

Bolted keels are clearly a design defect. They fail even a simple engineering analysis in terms of durability and survivability.

In the boats we're talking about the choice was made, not to benefit the end user, but to benefit the manufacturer....
Besides in what regards to that Beneteau 55, if we take into account what has transpired about it, it was not a structural design defect or hull build defect but a problem related with a full forward tank of water becoming lose in bad weather causing the damage.

That can have to do with a defect in building (not having fixed the tank properly accordingly to specifications) or a defect in design (the fixation of the tank not being properly designed).

Given the vast experience of Beneteau in what regards building boats I would say the first is the more probable and that would explain why no boats have been called to have the problem fixed.

Or maybe they have, maybe it does not regards all the boats, but just some. A correction, even if it regards an improper design of the tank fixation, would be a simple one to execute, it could have been done by dealers without we having had any knowledge about it.

Unless there are any owner of a Beneteau Oceanis 55 around we would never know more about that, but it is surely highly improbable that the Oceanis 55 has a problem that can lead to other boats to be sunk without Beneteau doing nothing about it.

It would be very damaging for their reputation and it would reflect very negatively on their sales, but one thing is to do something about it (if it was a design defect on the tank fixation and not a build defect), other is to make it publicly.
Polux is online now   Reply With Quote
Old 18-12-2015, 05:25   #690
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: Oyster Problems?

Who in the right mind choose to install a water tank on top of a bow thruster, sounds to me another lame idea....
__________________

__________________
neilpride is offline   Reply With Quote
Reply

Tags
oyster

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not 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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Oyster 53 vs Oyster 56 thoreed Monohull Sailboats 7 08-03-2015 22:09
Oyster Lightwave 48 - Thoughts? NTD Monohull Sailboats 15 24-02-2010 15:47
Oyster Sloop Christeen (1883) Soundbounder Off Topic Forum 0 16-04-2009 07:54
Oyster 41 Talbot Monohull Sailboats 10 06-10-2008 18:50



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 06:34.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.