Carbon or Aluminium Mast ?

[MacG]

I am not generalizing. Referring to techniques we are well aware of withou coming to the point at all is no use either.

I was already using epoxy in 1968 when some part of the steering system broke of my Lambo Espada. Could be repaired at huge cost so I went to Fokker Aircraft and there they glued the whole piece with a product of Ciba Geigy.
Reluctantly one started to use epoxy in yachtbuilding in the middle '80's so carbo masts of 25 yr old is hardly believable unless one off made and using polyester resin, either ortho, iso or vinylester.
Fact is that on a normal cruising yacht the extra expense of a carbon mast is hardly justifiable unless you have too much liquid cash. A pure racing yacht yes, why not?
The contradiction in the whole story is that the strength of carbon in general is in the wrong direction. Tensile rather than compressive. One direction only.

[pbr]

Uh Mac, you better scroll back up and check out the link for the 1988 Freedom 38 for an example of a 25 year old PRODUCTION yacht with cf freestanding mast, they built plenty of them that are still around. As to the strength of carbon in tensile, have you heard of load path orientation and fiber stacking?, if your point was valid there would be a lot of broken cf fishing rods out there.
p.s. you can see an example of one in a 52ft. catamaran at www.hytechmarine.com
p.p.s. How much exactly is too much liquid cash?, US dollars please.

[rob denney]

Originally Posted by niel12

There's a whole lot of good reasons why one should use a carbon mast i just wonder what the downside is? or is it all the way!

I've been building carbon masts on and off for 15 years. Always with the aim of making them cheaper. I am not building them at present, but have close ties to 2 companies that are. I built an unstayed (glass, not carbon) Freedom mast in 1982.

There are few if any downsides. Most of the ones stated so far are as valid as the wood/fibreglass arguments 50 years ago and the mono/multi arguments 20 years ago.

A professionally built unstayed carbon mast for a multi with righting moment of 18 ton metres (40' cat weighing 6 tons) is currently about the same cost and weight as a stayed aluminium one with all it's rigging. Such a mast is shown in the video at

Visionarry Sailing - YouTube

A stayed carbon mast will be up to 60% the weight of an aluminium mast. It will be more expensive, how much will depend on the spec.

A huge advantage of carbon masts is that they can be easily built by anyone with minimal skills and the desire to try. Built carefully, they will be every bit as good as a professionally built version, but much cheaper.

I am unsure of my status on this group as in the past I have been chastised for quoting prices. If I am allowed to, I will answer some of the questions asked thus far and supply numbers to support the claims above. If not, anyone who wants them can email me directly at harryproa@gmail.com.

regards,

rob denney

[Cheechako]

Remember the Americas Cup boat that broke in half in light air? Engineered by the worlds best!
Any questions?
Seriously, I think you are not supposed to drill any holes etc in Carbon Fiber masts... I may be wrong, but the whole thing just seems fraught with problems and risks... Rig's on cats are subjected to more stress than a mono also.... Not saying it wont be OK, but do you really need to be worrying?

[s/v Jedi]

This all brings the question if I can have in-mast furling with my carbon mast? And how about an unstayed one?

ciao!
Nick.

[Cheechako]

Originally Posted by s/v Jedi

This all brings the question if I can have in-mast furling with my carbon mast? And how about an unstayed one?

ciao!
Nick.

OH GAWD Nick!............... here we go!

[pbr]

The scantlings on that Americas cup boat "Young America" were pushed to the extreme around an involved measurment system, no comparison to the real world at all. You can drill holes in a carbon mast it depends on where and how big though. There have been in cf in mast furlers, cant be done though on freestanding. Go with furling boom if you have to have furling

[Jim Cate]

Originally Posted by pbr

The scantlings on that Americas cup boat "Young America" were pushed to the extreme around an involved measurment system, no comparison to the real world at all. You can drill holes in a carbon mast it depends on where and how big though. There have been in cf in mast furlers, cant be done though on freestanding. Go with furling boom if you have to have furling

Hey PBR,

I bet that he was referring to Australia 1, not Young America, FWIW.

And on that boat... I had an interesting conversation with John McConaghy (sp?), her designer. I sorta expected him to be a bit defensive about her, but he was not at all. Said something to the effect of " when you are designing at that level you really push the envelope to the limits. If things don't break now and then, you are likely being too conservative" He pointed out that the failure occurred in the lead up races when things were still being experimented with. Very interesting fellow! Incidentally, he has a gorgeous ALL carbon cruising boat of his own design... 48 ft OAL, 8 tonnes light ship, sumptuous interior fitout with lots of carbon fibre inlays in the timber, drop keel, and so on. Stunning boat that "the boys threw together during slack periods at the shop". Pays to be in the right business, I guess! BTW, he has actually done some coastal cruising in her, and now that I hear that he has retired, maybe we will see him about.

Cheers,

Jim

[Sand crab]

As this thread has now evolved to carbon mast building techniques I would just like to point out the Eric Sponberg (remember him?) has an article on DYI carbon masts.
State of the Art
Apparantly he has guided several amateurs in these successful builds. His entire site is a wealth of information. And thanks Jim Cate. Back at ya.

Also, Constellation Yachts in Key West builds a 2 piece mast. Interesting.
- Multihull Technologies Inc.

[threadkiller]

Astounding amount of misinformation ill informed opinion and prejudice in this thread. Race boats use carbon not because it is more expensive, but because it offers significant advantages over other choices. With proper engineering, it offers lower weight higher strength/stiffness with flexibility in the direction you desire. What is wrong with that? The price? Don't pay it. It can cost more...maybe not. Catanas offer carbon rigs, isn't that a production boat? It is not not like they don't do the engineering.


Jeez.

[delmarrey]

"Threadkiller"

Is that some kind of troll name, or doesn't want to show his authority by IDing himself? Be brave!

[44'cruisingcat]

Originally Posted by threadkiller

Astounding amount of misinformation ill informed opinion and prejudice in this thread.


Jeez.

Pretty much standard fare in the multihull forum....

As someone who has recently built and fitted a rig, the reason for not using carbon was simple - price. I got a brand new aluminium mast section, 16m by 235mm for $1200 delivered to my door.

Sure carbon would have been lighter, but for a stayed rig, the dollars per kilo saved simply didn't justify it.

[threadkiller]

Well, exactly.
THATS reasonable. Not wanting carbon due to lightning conductivity, or because it is newfangled and exotic, is not reasonable. If it fits your needs and budget, it can be a great choice. Spruce? Give me a break! Its 2012!

Mr 'D' - don't like my screen name? Too bad. Don't see you refuting my points.

[Malapoa]

Hello

A few comments on this issue, seen from France. As we are in the mullti section of this forum, comments do not apply to mono (ballast ratio, heeling, ...) ant neither to unstayed masts (seldom on multi).

CF masts are very often (90% ?) associated with wing shape and rotation. There are very few alu rotating mast. Wing shape associated to rotation increases sail efficiency and ease of handling (reefing). This is an expensive option but pretty common on "fast" cruisers (not saying racers).

UV protection and corrosion can be dealt with easily.

CF masts can be built precisely to specs due to the ability to continuously adjust shape et materials. Weight saving is significant and this is important on any multi; especially aloft.

Lightning risks (not more than alu) and brutal failure (shatter) are to be accepted. The only real downside is obviously the cost.

Patrice

[ejlindahl]

Does anyone have any idea if there is a difference in insurance premium amounts for a CF mast on a cruising boat vs an aluminum mast.