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Old 04-01-2016, 05:19   #871
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Re: Oyster Problems?

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Originally Posted by barnakiel View Post
Ha ha ha !!!

Another wooden boat with wooden chainplates???

Yep. I have seen this take before: like some designers believe the forces from the rig do not need to be transferred all the way to the hull/grid/frame.

Actually the problem is maybe not so much the mistake the designer or builder made but the fact that it took a while to come up: if it failed early on, the design would have been corrected. Same old thing always: build it well, see where it breaks, then build it better. Boat building the old(-er) way!

b.
From the photos it seem to me that the chainplate was on the main bulkhead. It was the main bulkhead that broke and as consequence the deck come apart.
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Old 04-01-2016, 05:28   #872
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Re: Oyster Problems?

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Interesting story and interesting 23 old design, quite light for an 11m boat (5020kg) specially considering that almost half of it is ballast.

The wave impact was so big that the shroud pull on chainplate broke the deck and the main bulkhead:

"Our tête-à-tête was interrupted by the loud roar of a mammoth breaking wave on the port side, further forward than any previous waves. I remember us staring at each other with “WTF?!” looks and then both turning toward the sound. There followed an even louder bang, accompanied by the sickening sound of tearing wood as we were hit by the wave. The lights went out and the boat felt as it if had been thrown sideways to starboard. "

Amazingly the boat was not capsized, or maybe not, with that huge B/D ratio instead of a rolling movement the big wave just induced a sideways big slide certainly with the boat almost lying flat on the water.

Regarding the accident, the skipper on the lesson's learned, does not blame the boat obviously thinking that all small boats can encounter situations that are over the breaking point of the boat and that rough "mammoth" wave was one of them.
I agree, an interesting incident.

This does support your view, made previously that there are skippers out there, who are happy with lightly made boats.

Just so this opinion is counterbalanced, let me say I think the skipper of this boat is wrong. The boat shouldn't have fallen apart like that, racer/cruiser or not. I would put it down as a lesson learned - to get a stronger boat next time.
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Old 04-01-2016, 06:12   #873
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Re: Oyster Problems?

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Originally Posted by med View Post
Carbocraft racing shells (rowing boats) were made with core of aluminium honey comb with some kind of carbon fibre/glass fibre inner and outer layers. They were top class shells in their time (1980s).
That technique was used on some Ocean racers too, one of the last the Stamm Open 60 that broke in a storm and that core was the responsible: the boat had already some years, suffered some big accidents and water ingress on the core (probably due to the previous accidents) caused the deterioration of the aluminum and the weakening of the hull at that point. The deterioration was a complex process that had to due with galvanic electric currents.

Honeycomb cores are used widely on the core of top boats, mostly made by a derived of kevlar (another aramid) Nomex, and now kevlar too.
http://www.plascore.com/download/dat...ore_Marine.pdf
Aramid Fiber (Nomex®/Kevlar®) Honeycomb Cores - Plascore
Kevlar Honeycomb: Core Composites

The idea that core materials, namely good ones like top closed foams, don't adhere closely to the fiberglass skin is a false one, If the building process is well made.

Also it seems not well understood the increase of strength and stiffness a cored hull has over a non cored one. Depending on the foam thickness a cored hull is to a same weight single skin hull 6 times stronger and 12 to 48 times stiffer. The only problem resides on abrasion resistance and that's why kevlar (or other type of abrasions resistance fiber) makes sense as part of a composite on the external layer of a core.

For the ones that what to learn more about cored hulls, a good article:
Foam Core Materials in the Marine Industry

Regarding foam ones there are a huge variety, they are not all equal and suit different purposes. For instance DIB, the manufacturer of one of the cores more used on Marine industries that is know by the generic name of Divinycell has 12 different foams under that name, with quite different properties:
Core Material

3A composites, other leader manufacturer that makes Airex, one of the more used cores on yachts, has 12 different Airex foams for marine use pointed to different uses as core material on a Yacht.
foam and balsa sandwich solutions for marine marketsÂ*- 3A Composites AirexBaltekBanova

The only reason honeycomb kevlar or Nomex cores are not more used on the marine industry instead of foam ones is price: They are expensive.
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Old 04-01-2016, 06:23   #874
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Re: Oyster Problems?

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Originally Posted by poiu View Post
I agree, an interesting incident.

This does support your view, made previously that there are skippers out there, who are happy with lightly made boats.

Just so this opinion is counterbalanced, let me say I think the skipper of this boat is wrong. The boat shouldn't have fallen apart like that, racer/cruiser or not. I would put it down as a lesson learned - to get a stronger boat next time.
You are contradicting yourself: Obviously the skipper of that boat, even after the accident, is satisfied with his choice of boat.

And the contradiction continues when you state that the skipper of that boat is "wrong" on the choice he has made, even if he is clearly satisfied with it.

With another type of boat of the same size, the type you favor, with a less stability, a lower AVS, the boat would probably have been rolled and inverted with unknown consequences.
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Old 04-01-2016, 06:49   #875
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Re: Oyster Problems?

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Originally Posted by Polux View Post
You are contradicting yourself: Obviously the skipper of that boat, even after the accident, is satisfied with his choice of boat.

And the contradiction continues when you state that the skipper of that boat is "wrong" on the choice he has made, even if he is clearly satisfied with it.

With another type of boat of the same size, the type you favor, with a less stability, a lower AVS, the boat would probably have been rolled and inverted with unknown consequences.
No, I am not contradicting myself. I am contradicting the skipper's opinion.

I perhaps should have supported my comments, but I thought it obvious. Had the boat been in wetter conditions it may well have been flooded and sunk and so was put in jeopardy by a rogue wave. Every boat will hit a rogue wave sooner or later and it is wrong to put ones life in the balance like that from a certain event.
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Old 04-01-2016, 07:58   #876
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Re: Oyster Problems?

This is just my guess, but I found that chainplate short in length..,,,,
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Old 04-01-2016, 08:06   #877
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Re: Oyster Problems?

Quote:
Originally Posted by Polux View Post
You are contradicting yourself: Obviously the skipper of that boat, even after the accident, is satisfied with his choice of boat.

And the contradiction continues when you state that the skipper of that boat is "wrong" on the choice he has made, even if he is clearly satisfied with it.

With another type of boat of the same size, the type you favor, with a less stability, a lower AVS, the boat would probably have been rolled and inverted with unknown consequences.
Obviously if that chainplate instead of been bolted to a ply main bulkhead had been bolted to the hull that would not have happened..

Wood? oh yeah , just for carpenters.....
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Old 04-01-2016, 08:30   #878
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Re: Oyster Problems?

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Originally Posted by poiu View Post
No, I am not contradicting myself. I am contradicting the skipper's opinion.
..
Quote:
Originally Posted by poiu View Post
This does support your view, made previously that there are skippers out there, who are happy with lightly made boats. ...let me say I think the skipper of this boat is wrong...
That goes well with your thought about sailboats that it is easy to resume: I like and prefer one type of boat (whatever the reasons) so all should like the type of boat I like and the ones that like or prefer other types of boats are wrong (whatever the reasons) even if they are satisfied with them

The contradiction regards saying that there are not skippers who are happy with lightly made boats (obviously there are) and to state after that the ones that are happy with them are wrong

Note that even if I like and prefer fast light boats, that can be quite strong, don't consider "wrong" the ones that prefer slow heavy boats built with older technologies and materials. Just sailors with a different taste in what regards sailing and sailing boats.
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Old 04-01-2016, 08:48   #879
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Re: Oyster Problems?

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Originally Posted by neilpride View Post
Obviously if that chainplate instead of been bolted to a ply main bulkhead had been bolted to the hull that would not have happened..

Wood? oh yeah , just for carpenters.....
Any material and any system has limitations in what regards the charge it is able to support. It is only empty speculation to make guesses about the size of the wave, that the skipper called a "mammoth rogue wave" that hit the boat and the scale of the efforts involved, certainly not the ones the boat was intended to support.

Regarding plywood bulkheads for supporting the rig efforts many boats use them, including production fiberglass boats and it is only a question of good dimension, the way they are fixed to the boat and how they are connected with the rest of the boat structure.

Plywood is a very strong material and wood, namely used the way it was used on that sailboat (strip cedar/epoxy) can provide very light and strong boats.
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Old 04-01-2016, 09:01   #880
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Re: Oyster Problems?

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Originally Posted by Polux View Post
Any material and any system has limitations in what regards the charge it is able to support. It is only empty speculation to make guesses about the size of the wave, that the skipper called a "mammoth rogue wave" that hit the boat and the scale of the efforts involved, certainly not the ones the boat was intended to support.

Regarding plywood bulkheads for supporting the rig efforts many boats use them, including production fiberglass boats and it is only a question of good dimension, the way they are fixed to the boat and how they are connected with the rest of the boat structure.

Plywood is a very strong material and wood, namely used the way it was used on that sailboat (strip cedar/epoxy) can provide very light and strong boats.
yep, I see in this case how strong is a ply bulkhead for supporting a rig, lets say in any case the chainplate and rig fail way way before the hull in a strong boat....
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Old 17-02-2016, 03:45   #881
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Re: Oyster Problems?

In Yacht.de;


"Wir werden daraus lernen"Â*|Â*YACHT.DE


"Die Ursache für den Kielabriss an einer Oyster 825 ist geklärt – Werftchef David Tydeman räumt Laminierfehler in der Bodengruppe ein "


cheers,
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Old 17-02-2016, 05:43   #882
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Re: Oyster Problems?

Thank you JJ.. translated .


Half a year after the emergency at sea off the Spanish coast Oyster has announced the results of an extensive internal root cause analysis. Accordingly, the Kiel demolition was the result of fatigue failure of the underbody, which finally collapsed completely.

*Extract from the Report for YACHT Kiel loss of Oyster 825
© YACHT
Extract from the Report for YACHT Kiel loss of Oyster 825

The YACHT became the first sailing magazine insight into the investigation report and could speak both with designer Rob Humphreys as well with Oyster CEO David Tydeman about the background. There were also interviews with the professional skipper of misfortune-boat Alessio Cannoni and with international structures and FRP experts.

How did the keel loss, as the crew despite immediate capsize was uninjured, what went wrong in the production and how Oyster has responded to the incident - all you read in the ten-page exclusive report in YACHT 5-2016 - on newsstands now or digital as an app and e-paper here.

Where we can see the final report in english'?
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Old 17-02-2016, 06:34   #883
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Re: Oyster Problems?

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Originally Posted by JJ77 View Post
In Yacht.de;


"Wir werden daraus lernen"Â*|Â*YACHT.DE


"Die Ursache für den Kielabriss an einer Oyster 825 ist geklärt – Werftchef David Tydeman räumt Laminierfehler in der Bodengruppe ein "
cheers,
JJ
Thanks for posting that.

That is very interesting as well as Oyster admitting a lamination deffect:
"David Tydeman admits lamination defect "

Obviously there can be two lamination defects, one due to the boat not being made according to specifications other the specifications not being correct. It would be very interesting to try to understand what is the case and if the later that means more trouble for Oyster since there can be many boats that soon or later could have stress fatigue that leads to a keel collapse.

Obviously you can read German so I count on you to post about the more interesting parts of that article on the May edition of Yacht de magazine, if they don't post the article on line ;-).
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Old 17-02-2016, 11:02   #884
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Re: Oyster Problems?

Pretty bad all in all for a brand pretending to be at the high end of the sailing boat market. Whatever the excuses, it is plainly bad and unacceptable really. Makes me laugh about all the joking about Bavaria´s losing keels too, everybody always immediately jokes about on forums. As relatively, there is a higher chance you lose a keel on an Oyster now!

I think Oyster can thank the good lord on their knees nobody got seriously injured or worse. As if there was loss of life, I think things would have been VERY different.

Still, I remain very much an Oyster fan. They are great boats. Just a shame the management hasn´t been capable of some descent quality control. Heads should roll over this I think.
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Old 17-02-2016, 12:09   #885
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Re: Oyster Problems?

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Originally Posted by marco@onyva View Post
Pretty bad all in all for a brand pretending to be at the high end of the sailing boat market. Whatever the excuses, it is plainly bad and unacceptable really. Makes me laugh about all the joking about Bavaria´s losing keels too, everybody always immediately jokes about on forums. As relatively, there is a higher chance you lose a keel on an Oyster now!

I think Oyster can thank the good lord on their knees nobody got seriously injured or worse. As if there was loss of life, I think things would have been VERY different.

Still, I remain very much an Oyster fan. They are great boats. Just a shame the management hasn´t been capable of some descent quality control. Heads should roll over this I think.
I haven't noticed anyone giving Oyster any quarter on this one. If anything, there are more defenders of the less expensive boats when such catastrophes occur, and not always for good cause. When it comes to failures of basic structural components such as hulls, keels & rudders, there is understandable and usually justifiable alarm, regardless of brand.
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