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Old 18-02-2016, 08:33   #916
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Re: Oyster Problems?

I give the owners (and skipper) of that oyster great credit for forcing this issue out into the open. It is more healthy for everyone to know, rather than be covered all up by NDA's as is more typical in this industry.

I am using this thread just to consolidate some of my thoughts across various other 'failure' threads.

I guess I (now) think there are 4 factors:
- reliability/quality - what is acceptable to us in quality/reliability - there is not a lot of regular NDT here and the production processes are not very stable;
- duty cycle, should charter boats being put to near 100% commercial duty cycles really be built the same way as recreational boats?
- maintenance/inspection - questions like: If you touch bottom, should we expect to continue across bass straights or should we be headed for the nearest haul out, and should those other Oysters 825's have already found the poor laminate in their key structure without this one-off oyster investigation ;
- specified conditions - are we expecting our boats to be designed and built to be able to survive 1998 Sydney to Hobart conditions. If not, to what standard of conditions do we expect them to survive?

I know EXACTLY how each of these questions was answered when I built our own boat, but I find them difficult to answer for boats like oyster and Bendy where the owners objectives and expectations are so broad.
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Old 18-02-2016, 08:40   #917
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Re: Oyster Problems?

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. . . - specified conditions - are we expecting our boats to be designed and built to be able to survive 1998 Sydney to Hobart conditions. If not, to what standard of conditions do we expect them to survive? . . .
The STRUCTURE, hell yes, and more than those conditions. The structure should not break. Wings should not fall off aeroplanes, period, and keels and rudders should not fall off offshore cruising boats.
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Old 18-02-2016, 08:41   #918
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Re: Oyster Problems?

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The STRUCTURE, hell yes, and more than those conditions. The structure should not break. Wings should not fall off aeroplanes, period, and keels and rudders should not fall off offshore cruising boats.
So, how do you feel about the typical sliding glass walls on cats then?

They are not typically very vulnerable, but in Sydney to Hobart conditions (HUGE breaking waves) they would have been.

And do you think rudders should be able to survive say log strikes? There is a lot of debris in the ocean, unlike up in the sky (although GE jet engines were in fact designed to survive a strike from a frozen chicken )
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Old 18-02-2016, 08:53   #919
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Re: Oyster Problems?

Very unlikely to found those Sydney to Hobart conditions again, and I guess a mono can have weak points to in that kind of weather,, not trying to defend those lame glass sliding doors in some multis but honestly not a issue unless you are in the middle of the hell....
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Old 18-02-2016, 08:57   #920
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Re: Oyster Problems?

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Originally Posted by estarzinger View Post
So, how do you feel about the typical sliding glass walls on cats then?

They are not typically very vulnerable, but in Sydney to Hobart conditions (HUGE breaking waves) they would have been.

And do you think rudders should be able to survive say log strikes? There is a lot of debris in the ocean, unlike up in the sky (although GE jet engines were in fact designed to survive a strike from a frozen chicken )
You ask hard questions

I have no opinion about sliding doors on cats because I don't really understand cats and prefer not to speculate. I would only say that I've never heard of a cat lost because the sliding doors were breached, so I doubt it's a big problem.

Concerning log strikes: our rudders absolutely should be able to survive them. Absolutely. As you said, there is a lot of debris in the ocean. That's why the lower part of the rudder should break off without bending and jamming the shaft, leaving you with some kind of steerage.

As to the one in a million case where the log is scraping along the skin and catches the rudder right at the base -- probably there's nothing practical we can do about that, and the chances fall within Sigma 6 parameters.
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Old 18-02-2016, 09:22   #921
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Re: Oyster Problems?

^^ That's reasonable.

On Hawk we designed the rudder to survive essentially anything - including log and rock strikes at full speed. And we did (unfortunately) test it in the real world and (fortunately) the engineering was correct.

Funny story . . . when we were in Chile we had a new rudder designed (deeper with better shape). The designer's included a crumple zone at the bottom, for the various reasons that have been discussed in threads here. We had a Chilean aluminum yard that was building sophisticated fast ferries build the rudder (1/10 the cost of doing it in the US). They did a totally terrific job. But when we went to pick it up, the head engineer took me aside and told me 'we think your designer made a mistake and made the bottom of the rudder too weak, so we redesigned it and built it to be full strength'. I just smiled and thanked him. And actually it has worked out well, because we have twice wacked it on things that probably would have crumpled the crumple zone and required some expensive work, and instead it just put a small dent it in which we filled and faired out at next haul out.
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Old 18-02-2016, 10:00   #922
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Re: Oyster Problems?

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And do you think rudders should be able to survi]ve say log strikes
Yes.

That is why I would only ever want a boat with a keel before the rudder so that if I run over a log, the rudder stays intact.

Similarly, I don't want to have a rope wrapped around the prop if I run over a lobster pot.

But other people are prepared to compromise on these things and have boats with fin keels, motor boats with IPS drives etc etc.
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Old 18-02-2016, 10:26   #923
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Re: Oyster Problems?

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For moderate coastal sailing, you don't need to inspect the rig or change the rigging so often, but offshore sailing is different, involving more miles (by factors of 10 or more) and more stress, and much worse consequences in case of failure.

I don't know any offshore sailors who inspect their rigs as seldom as every 4 years. I do a major inspection of mine every year (you don't need the mast out to do it), and minor inspections every time I'm up in a bosun's chair. This year I will have it done professionally.
...
I am just talking about what are the maintenance schedule pointed for some major rig providers. Most insurance companies will not pay, at least fully, a rig breakage if the rig is more than 8 years old, following that schedule.

Regarding what you do, I would not had the idea that you were misinformed regarding maintenance of the boat but I would say most are. You only have to follow some threads about rig maintenance and the right time to change the rig to see that many consider a 10 year old rig as almost new.

Regarding coastal not needing to be as frequently changed it all has to do with the use one gives to the boat and the conditions the boat is sailed on.

It can even be more stressed on coastal conditions that do Ocean passages, specially if one races the boat but I agree with you that if the boat is not stressed the rig will last longer and anyway the problems of a failure near a coast can be far less severe than the ones on the middle of an Ocean and therefore special care is needed regarding its condition if one is going to cross an Ocean.
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Old 18-02-2016, 10:31   #924
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Re: Oyster Problems?

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Talking about mast and rigging, it depend if the boat is insured or not, by the way we inspect the mast and rigging for a whole charter fleet in a regular basis, insurance rules.
Insurance rules based on the maintenance schedule suggested by mast and rig providers, I bet.
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Old 18-02-2016, 10:37   #925
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Re: Oyster Problems?

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Originally Posted by estarzinger View Post
So, how do you feel about the typical sliding glass walls on cats then?

They are not typically very vulnerable, but in Sydney to Hobart conditions (HUGE breaking waves) they would have been.
...
Are you sure about sliding glass walls? I thought they were forbidden by the RCD. What I see is fixed Plexiglas walls with hatches. The only sliding walls are on the rear of the boat were the possibility of being caught by a wave is really minimal.
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Old 18-02-2016, 10:55   #926
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Re: Oyster Problems?

Quote:
Originally Posted by Polux View Post
I am just talking about what are the maintenance schedule pointed for some major rig providers. Most insurance companies will not pay, at least fully, a rig breakage if the rig is more than 8 years old, following that schedule.

Regarding what you do, I would not had the idea that you were misinformed regarding maintenance of the boat but I would say most are. You only have to follow some threads about rig maintenance and the right time to change the rig to see that many consider a 10 year old rig as almost new.

Regarding coastal not needing to be as frequently changed it all has to do with the use one gives to the boat and the conditions the boat is sailed on.

It can even be more stressed on coastal conditions that do Ocean passages, specially if one races the boat but I agree with you that if the boat is not stressed the rig will last longer and anyway the problems of a failure near a coast can be far less severe than the ones on the middle of an Ocean and therefore special care is needed regarding its condition if one is going to cross an Ocean.
Yes, I think for sure that what wears out a rig is rather unpredictable. I heard that rolling at a mooring puts cyclical loads on the rig which can wear it out quickly. I guess that's why you need to keep up the inspections.

8 years for replacement sounds low to me except in very hard, very high mileage use. My insurance company (Pantaenius) doesn't have any particular schedule. I changed my standing rigging after four years of hard use by me, and eight years of very light use by the P.O., so 12 years altogether, and I could have waited. There were no broken strands and nothing really wearing out. Once I had the mast out, however, it would be have been stupid not to replace it, as it is quite expensive and complex (requiring two cranes) to get my mast out.

It depends a lot on how the rig is designed, too -- a higher stressed, higher aspect rig with lighter standing rigging will obviously wear out the standing rigger faster than a more conservative rig. My rig is somewhere in between the two extremes.

So I don't think you can pick a number which applies to everyone, but I would guess that 10 years must be around the shortest replacement interval for everything but racing boats or boats doing serial circumnavigations, so I don't think 15 years in some cases is unreasonable at all. You have to inspect every rig individually to know when it needs to be replaced.
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Old 18-02-2016, 10:57   #927
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Re: Oyster Problems?

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Insurance rules based on the maintenance schedule suggested by mast and rig providers, I bet.
There is no such finite life for a rig based on mast makers, or rig makers ... all depend in how well is maintained, obviously 8 years is nothing for a mast , even for wires and rigging .. Riggers dont have a manual backup suplied by rigging dealers or brands in when they should change this stuff or the other ...

Saying that, imagine a 3 or 4 spreader big $$$ mast in the trash every 8 years... i see spars with 20 plus years maintained in excellent condition and insured, its a matter of regular inspections, and for the rigging some companys say every 5 ,,others say every 3 .. i remember a big swan when the insurance company call for rod replacement every 3 years...
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Old 18-02-2016, 11:57   #928
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Re: Oyster Problems?

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There is no such finite life for a rig based on mast makers, or rig makers ... all depend in how well is maintained, obviously 8 years is nothing for a mast , even for wires and rigging .. Riggers dont have a manual backup suplied by rigging dealers or brands in when they should change this stuff or the other ...

Saying that, imagine a 3 or 4 spreader big $$$ mast in the trash every 8 years... i see spars with 20 plus years maintained in excellent condition and insured, its a matter of regular inspections, and for the rigging some companys say every 5 ,,others say every 3 .. i remember a big swan when the insurance company call for rod replacement every 3 years...
Yes contrary to what most think rod lasts less than normal rigging. With rod the terminals should be changed each 4/5 years and the all rigging each 8 years. Maybe I was over generalizing but today's most expensive boats have rod on the rigging, at least the performance ones.

Regarding the older strand rigging the period to a full inspection is 10 to 15 years, depending on the use but by full I mean ultrasound and that is so expensive that it makes more sense to change all rig at that time.
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Old 18-02-2016, 12:03   #929
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Re: Oyster Problems?

Paolo there is no ultrasound test for 1x19 ss wire , its a matter of common sense and visual inspections,, DYE tests, and destructive test... that's why insurance companys put a shorter interval between changes ...
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Old 18-02-2016, 12:21   #930
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Re: Oyster Problems?

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Paolo there is no ultrasound test for 1x19 ss wire , its a matter of common sense and visual inspections,, DYE tests, and destructive test... that's why insurance companys put a shorter interval between changes ...
I was not talking about rod but about strand rigging and G&G the main Italian provider and one of the main European ones, talks about using ultrasound. The rigs are taken out and taken to their installations were they have the technological means to make testing, including ultrasound. I know because mine is being dismounted to be sent there.

With rod they say that after 8 years it should be disposed if it was used normally and in that in no case the 12 years should be crossed.

"Il sartiame spiroidale ad esempio ha una vita media tra i 10 e i 15 anni, a seconda di come ha lavorato. Oltre questo periodo sarebbe buona cosa un controllo accurato a mezzo liquidi penetranti o ultrasuoni, ma i costi di queste indagini sono talmente elevati rispetto al valore medio di un sartiame che possiamo tranquillamente affermare che sia piů conveniente decidere di rifare il sartiame"."

G&G rigging - Supporto tecnico > Manutenzione sartiame
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