Would you have a Carbon mast

Seajet said:
Lots of potential problems in the long term, maybe the sort of people who have carbon masts only think short term then sell on as SEP; Someone Else's Problem.
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Experience shows that all these long term potential problems don't exist. Mine is 15 years old and apart from the gelcoat losing its shine, looks brand new. All masts have a life limit - aluminum corrodes, especially underneath stainless fittings, and wood rots. I don't envisage carbon masts have a shorter life than any other material. If you don't want a carbon mast, like fully battened sails, it's simple: don't have one.
 
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Angus,

if you read what I said... I'd be more concerned with the impact of hard sharp objects, the very nasty damage I photographed of the insides of carbon structures was completely invisible on the exterior, if anyone dropped a tool on a Harrier II wing panic ensued and the ultrasound bods were wheeled in.

Funny you should mention wooden masts and lightning, a vintage 20' yawl at my moorings with wooden masts was hit, blowing out a plank and sinking her, when she was surrounded by much taller alloy masts; apart from proving sod's law is alive and well, we supposed the rain made a constant path.
 
should add that some modern cars are now appearing with carbon epoxy structures. given the safety checks that cover vehicles I would be very surprised if there was any long term safety question.

The likelyhood however is that because carbon is expensive, its likely to be used in high performance light weight high cost uses with thickness kept to the minimum - your Harrier wings are an example of this. So just like with ocean racing boats you will get reports of failures of carbon masts. Those made more solidly for cruising boats like my pals will be a different issue altogether.

They appeal to me because they can allow the absence of rigging.
 
Seajet said:
Angus,

if you read what I said... I'd be more concerned with the impact of hard sharp objects...
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You did mention lightening damage too. As for impact with sharp objects, I can't see that a mast is really vulnerable to that. I know that carbon spinnaker poles sometimes shatter, but they do get chucked around and bashed by foredeck gorillas. Although CFRP is less tough than aluminum alloy, it's not exactly glass. There is still a considerable wall thickness to carbon masts, and it would take some concerted bashing with a hammer to get it to break. I just can't see that happening to a mast, and the lack of brittle failures of carbon masts in reality bears that out.
 
Seajet said:
Angus,

if you read what I said... I'd be more concerned with the impact of hard sharp objects, the very nasty damage I photographed of the insides of carbon structures was completely invisible on the exterior, if anyone dropped a tool on a Harrier II wing panic ensued and the ultrasound bods were wheeled in.
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So - you are basing your concern about carbon masts on a structure that was not designed to absorb impacts, in the very early days of using carbon? Carbon fibre is much better understood now, and techniques and processes are much better - and better controlled. Your concern is a bit like being concerned about aluminium masts because some Comets dropped out of the sky due to aluminium metal fatigue.

There must be thousands of carbon masts sailing the oceans now, and I don't think they are failing at any particularly high rate.

Here is my prediction: in the future, some carbon masts will fail, but most won't. Some aluminium masts will fail, but most won't. Some wooden masts will fail, but most won't.

All things being equal, if I was given a choice of masts I would choose carbon.
 
The AV-8B/GR5 wing was actually meant to be robust, the Harrier was originally meant to be able to be dispersed among trees away from airfields when the Russians rolled in, and the tin wing jobs - which includes the Sea Harrier and GR3 used in the Falklands War - were very good for this, any dent was either tolerated of hammered out.

It was not ' the early days of carbon fibre ' but was the largest C/F structure of the time.

Angus you mention spinnaker poles, well one of those sproinging into the mast under the usual inward forces would be exactly the sort of hard sharp impact I'd worry about !

This was the first takeoff of a UK Harrier II GR5; the green nose and wing, + the yellow horizontal tailplane are carbon fibre.

View attachment 49118
 
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If your concern was rational and had any validity we would be hearing stories of a high percentage of carbon masts failing. We don't hear that.

Once again, why don't you have concerns about aluminium masts as a result of the Comet crashes?
 
Seajet said:
Angus you mention spinnaker poles, well one of those sproinging into the mast under the usual inward forces would be exactly the sort of hard sharp impact I'd worry about !
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They are a lot less brittle than you imagine them to be. They are not aeroplane wings. However, I expect you will never be convinced, so all I can suggest is don't have one, and you will have nothing to worry about. I'll do the worrying for you. Pleased to see that you are posting pictures of Harriers in boaty threads again though. Any more you can share?
 
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bbg said:
If your concern was rational and had any validity we would be hearing stories of a high percentage of carbon masts failing. We don't hear that.

Once again, why don't you have concerns about aluminium masts as a result of the Comet crashes?
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The only unstayed aluminium masts that I have seen regularly fail in tough conditions are Laser Dinghy Top sections.

In contrast I have seen plenty of windsurfer rigs out in as tough or tougher conditions and survive some serious crew impacts!

Possibly the application of the technology has moved on in the last 35 years or so. Certainly Airbus and Boeing are going hard for it now!

I also believe that the round tapered sections is probably one of the most suited applications for engineered CF products.
 
bbg said:
So - you are basing your concern about carbon masts on a structure that was not designed to absorb impacts, in the very early days of using carbon? Carbon fibre is much better understood now, and techniques and processes are much better - and better controlled. Your concern is a bit like being concerned about aluminium masts because some Comets dropped out of the sky due to aluminium metal fatigue.

There must be thousands of carbon masts sailing the oceans now, and I don't think they are failing at any particularly high rate.

Here is my prediction: in the future, some carbon masts will fail, but most won't. Some aluminium masts will fail, but most won't. Some wooden masts will fail, but most won't.

All things being equal, if I was given a choice of masts I would choose carbon.
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bbg & TSB240,

actually I was taught as an apprentice the lessons learned from the Comet accidents.

All holes for sheaves etc in my mast and the others I've worked on have rounded corners to the apertures; the Comet windows failed because they had straight edges and sharp corners, so cracks found it easy to propagate outwards.

I asked a simple question, so don't need to be told what I'm frightened of; I hardly think alloy is infallible, but I suggest it's a helluva lot more predictable.

No-one has answered me yet as to hard sharp impacts and interior damage...
 
Seajet said:
No-one has answered me yet as to hard sharp impacts and interior damage...
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I think AngusMcDoon did - in a way - in #61. The evidence is empirical. There are no reports of hard sharp impacts and interior damage being a problem - so they aren't a problem. Carbon masts don't seem to be failing in great numbers.

Think what you will. The rest of us will enjoy the benefits of modern technology.

FWIW I've got a friend who is a boat builder. He knows materials. When he specced a new keel for his boat, he specced carbon (with a lead bulb at the bottom). And the entire structure holding the keel in the boat is carbon. I will sleep soundly when we are 100 miles out at sea. Even if we hit something hard and sharp with the keel.
 
Who said I'm worried, but I'm allowed to be curious aren't I ?

No my question hasn't been answered yet, apart from ' most carbon masts are still standing '.

This is like the Acme ejection seat co saying ' We've never had any complaints '...:rolleyes:
 
There may not be a technical answer to your question, but you have not actually identified the specific issue nor the root cause of that issue. But there has been an empirical answer to your question which is: the concern you raise has not been seen to exist in practice.

I don't understand your analogy. You have raised a concern with a material. That concern is not reflected in real-world use. Masts are not actually failing in the way you are concerned they might. Either the event you are concerned about is not happening in this application, or it is happening but is not causing any problems.

Either way, think what you will but your concern is irrational.
 
Seajet said:
No my question hasn't been answered yet, apart from ' most carbon masts are still standing '.
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At the end of the day, that's all that really matters. We can worry about non-existent risks until the cows come home, but as long as the hulls keep the water out, the mast stays up, and I've got somewhere to keep my parsnips, I'm going sailing.
 
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bbg said:
There may not be a technical answer to your question, but you have not actually identified the specific issue nor the root cause of that issue. But there has been an empirical answer to your question which is: the concern you raise has not been seen to exist in practice.

I don't understand your analogy. You have raised a concern with a material. That concern is not reflected in real-world use. Masts are not actually failing in the way you are concerned they might. Either the event you are concerned about is not happening in this application, or it is happening but is not causing any problems.

Either way, think what you will but your concern is irrational.
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The RAF, USAF, USMC, Boeing, McDonnel, NASA and BAe didn't think it irrational.

I identified the problem of hard sharp impacts causing internal delamination.

This obviously qualifies as an Awkward Question as nobody here knows the problem let alone an answer for me.

Forget it...:rolleyes:
 
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