How do I build a mast out of Carbon Fiber or glass

[Lowcarb]

Hello

I have been searching on how to build a carbon fiber mast. I have located a site on how to build sections out of fiberglass and then assemble them, but, I am sure there are many out there who know how to build a CBF Mast with allot of details/plans. I hope someone would help with this quest and I really don't want to goof it up and get caught out on the ocean with a defective mast. I am sure there will be many who say.."Buy one", ok give me the money and I will, until then help me cut cost and I will build one. I built the last 45' mast out of wood and it still stand today fine after 50knot winds 7.25knott hull speeds. I think if it works for building fiberglass masts then it should work for CBF masts. Any ideas would help and be appreciated so I thank you up front...

Here is what I have found so far: http://www.themultihull.net/st2.htm

[aldo salvato]

I don't know how to build a carbon fiber mast,however,seen that you have built a wooden mast,I would truly appreciate it if you could tell me where I could find printed instructions on how to build one, or repair the one I have.:p ;)

[Guest]

I have not attemped building a mast yet but I have been thinking about it for a couple of years. One thing that I would consider is leaving a rigid foam core in the mast. Carbon fiber takes compressive loads better than glass but still not nearly as well as aluminum. A rigid foam would help resist buckling. The core would also make the mast positively buoyant should you get knocked down. I know that running the halyards externally is a problem but I'm not sure that I would want to cut holes in the mast for the halyards exits anyway.
Another thing to consider is the orientation of the fibers. I would think that about 75% of the fibers should run along the length of the mast. Maybe a unidirectional tape would work good for this and cover each layer of unidirectional tape with a layer of biaxial +45 -45 and finish the outside with a biaxial 0 90.
It would be nice if you could vacuum bag the whole thing but I don't think its feasable even with a very slow hardener on a cool day I think its just too big if your building anything over about 20 ft.
If you do try it, let us know how it goes. I think a lot of people consider building one but I don't know of anyone that has actually done it.
Good luck

[Lowcarb]

Aldo, my list is pretty long since I usually down load the whole webpage and save it. I could zip that up and send it to you. Pop me a PM and leave your email. I will send you the zip.

I am also considering selling 2 beautiful ketch rigged masts with sails and all the riggings if your interested since I am replacing them with carbon fiber masts. I also have photos of the riggings;

[Lowcarb]

More pictures

[Lowcarb]

More pictures again

[Lowcarb]

another view

[Lowcarb]

The original Vicktor Harrasty brochure she was build and rigged as

[Tim B]

Sounds Like you're about to start one damn big project Kelly. I suggest that when you start to mould the mast, that you get a team of people, four or six of you (even numbers divide into neat teams), breif everyone on what you're going to do, then do it.

Steve Tellardin suggests at the end of his article, that you should perhaps seek the advice of a proffessional yacht designer, do seek advice. There's nothing worse that being stuck on the water with a broken mast. What's more, you lose the price advantage. If anything, build it 'too strong', "if it breaks it wasn't strong enough" to quote an old expression. There is no real reason why you couldn't build it as a one peice layup. One thing to note is that if you are using glass fibre tape, overlap the tape at different places in the mast layup, if you have to join several longitudinal strips at different points around the diameter. Another thing is to make it over-length, then shorten the mast. That will ensure that the deck-end is totally consolidated. Personally, I'd use epoxy resin for the layup, three reasons:

1) It's lighter than polyester (and you can get a better glass/resin ratio).
2) It's a lot easier to work.
3) It doesn't dissolve foam when you try to use it.

You may also be able to make a test-model. Once you have made it, rig it, and test it to destruction. Measure the forces on each rigging wire. That will give you an idea of the forces the laminate will withstand. Note also how it breaks.

Cheers, and good luck,

Tim B.

[Lowcarb]

Thanks Tim

[Guest]

Hi

I also for a short time considered laying a mast out of carbon fibre. These were my plans:

the mast should be 16 meters in length (43 ft sloop); building it up just like a boat's hull: moulds in about 1 meter distance; thin stringers along the length of mast, covering it with balsa veneer for giving shape, layering unidirectional carbon fibre lengthwise, in change with bidirectional carbon fibre in +/- 45 deg; working with epoxy; if i'd put as many layers up as an aluminium mast would be, i guess i was on the right side in wall thickness (5 mm). but i gave it up, just as i thought it wasn't worth the risk, better buy an aluminium mast and stick to prooved stuff than having a broken mast in the middle of the atlantic and paddling along to the caribbean... the costs turned out to be almost as high as an aluminium mast, not included work and the risk factor.

[kudu]

Hi Kelly...Checkout sponberg.com or contact Eric Sponberg in the members section, he designs and builds carbon masts...

[kudu]

Correction...sponbergyachtdesign.com

[gonzo]

To build a mast you got to build a mold first. Then you need a vacuum bagging system. Remember that carbon fiber is brittle, so all the calculations for loads and the design for attachment points have to be done in advance. Working with high-tech materials is not easy. I discourage you from starting on a project so big. Start with small parts to learn how to work with the materials. When you do the calculations, remember there are many types of carbon fibers and of resins. Also the ratio of resin to fiber changes the characteristics of the material. Unless you have access to an infusion system, the best would be to buy prepregs.

[Unregistered]

To build a carbon fibre mast you will need a tapered mandrel (made from steel) you then lay up the carbonfibre as you would any epoxy-resin moulded product. The whole unit would then enter a heated oven and heat treated and cured. The sleel mandrel is then knocked out of the carbonfibre moulded mast. The whole thing would cost a bomb and youwould never retreive you cost /input. Although it is expensive to purchase a finnished product --you would save money in purchasing direct from a source and examining the product befor parting with loyts of cash

[guest]

check out the web site for the Cherub dinghy class in the UK ... (don't have the URL handy).

They've been building their own carbon gear for several years and there's a how-to there on building a Cherub mast in carbon. Not exactly the same size, I admit... but might be worthwhile reading for you.

Cheers,
Tony

[gggGuest]

check out the web site for the Cherub dinghy class in the UK ... (don't have the URL handy).

They've been building their own carbon gear for several years and there's a how-to there on building a Cherub mast in carbon. Not exactly the same size, I admit... but might be worthwhile reading for you.

Cheers,
Tony

http://www.sailingsource.com/cherub/masts.htm

[Fateh shareef]

What are the detailed cost involved in building a fiber boat (open) of 18 ft ?
Tools ,Materials,Manpower

[guest]

Hood Spars (http://www.hoodspars.com/spinning.htm)

[Guest]

http://www.hoodspars.com/images/180pole.jpg
http://www.hoodspars.com/images/Filament%20head1.JPG
http://www.hoodspars.com/images/filament3.JPG
http://www.hoodspars.com/images/winding%2070.JPG

[jack kern]

need to pick your brain a bit about the carbon fiber.
i would like to reinforce the upper 1/4 of a 35 ft carbon mast to make it stiffer. i am told 300 gm carbon tape would work and will start with three layers of maybe 4 inch i think. can you give me your thoughts on ordering this and where.

thanks, jack

[SouthernWing]

Hi Kelley Ann

I have also been searching for some information on building a carbon fibre mast. Thankyou for the URL. I was wondering if you have had any success yet and if so would you be willing to let me know what you have found. I will do likewise. Good hunting.\

Phill Wise

[JR-Shine]

We have just listed carbon fiber mast and pushpole kits. The material we stock would only be good for a max diameter of around 4", but it is available in larger sizes that would fit what you are looking for.

Here is the link:

http://www.boatbuildercentral.com/products.php?id=36&Carbon%20Fiber%20Mast%20and%20Push%20Pole%20Kits

Joel

[JR-Shine]

Here is a link to a site done by a builder using the above mentioned mast kits to make a 10 ft. long carbon fiber mast.

http://www.lmorocz.com/BoatBuilding/krakenbait.htm

Joel
Boatbuildercentral.com

[SouthernWing]

Thanks Joel, I will have a look at it.


Cheers Phill

[Karsten]

Hi Guys!
I don't want to discourage you too much but designing AND building a carbon mast is not easy.

1. There are many different carbon fibres with VERY different material properities around! There are high strength (HS) fibres which have "little" stiffness and high modulus (HM) fibres that are more expansive, very stiff but have "little" strength and then there is anything in between.

2. Carbon even has different material properties in different fibre directions. It has very little strength perpendicular to the fibre! This is important at fittings.

3. You can gretly influence the strength and stiffness of the mast simply by changing the orientation of the fibres! A mast with a wall thickness of 5mm might be fine if most fibres run in the up-down direction and fall to pieces if the fibres are wound around the mandrel perpendicular to the up- down direction. In that case you can almost cast the mast from resin only and leave the fibres out!

4. You have to use vacuum if you want to hand lay-up. Carbon doesn't get seethrough like glass. So you can't see air boubles under the cloth.

5. The risk investing a lot of money and time to design and built you own mast is enormous. Get at least a professional to design it and come up with a lay- up plan and materials list. At least you are reasonably sure that if your manufacturing process is up to scratch that the mast will be fine.

6. Ever tried to pull out a mandrel without a hydraulic press?

7. A good start is an existing aluminium mast that you know works. Find out what the mechanical properties of that mast are and then get a professional to design a carbon mast with the same mechanical properties (except for the weight obviously).

Wait a few years. Some companies are experimenting with "pulltruded" carbon masts. The manufacturing process is very similar to extruding aluminium but only with carbon fibres. It's a very cheap manufacturing process. The only problem is that you can't taper the profile. It's used for fibreglass ladders and all sorts of constant sections.

Cheers,
Karsten

[MikeJohns]

Why carbon fibre on a non-racing yacht?? Composite masts are fraught with problems even when proffessionally produced, as an engineer I wince at the thought of them. You would be far better advised to use aluminium masts on this boat.

[Eric Sponberg]

Gentlemen,

Karsten has some good points, masts are not easy to build, and you do have to pay very close attention to laminate details. One additional detail is that you have to be careful of thickness-to-diameter ratio, t/D. If this is not big enough, usually around 0.03 will do, then you risk the chance of the mast collapsing due to column buckling. That is, if the wall thickness is too thin for the diameter, the mast can buckle before it achieves its design strength. The reason for this phenomenon is because of the orthotropic nature of the laminate. There is more fiber running longitudinally than in off-axis directions, and this gives the laminate different strengths and stiffnesses in different directions. Therefore, too thin a laminate for the diameter and the mast is more prone to buckling collapse.

Contrary to Mike John's comment, there are good reasons to put a carbon fiber rig on a cruising yacht, simply for stability. A mast tube built of carbon weighs about 60% of the same mast built in aluminum. This reduces weight up top, which increases stability, which is always important, no matter what type of boat. Also, there are a number of fine builders available who have been building carbon fiber masts for many years now. The technology is established, although it is not simple. Most carbon fiber rigs survive just fine.

Eric

[MikeJohns]

Only the mast tube is 40% lighter, by the time you add the masthead fittings, stay and shroud fittings, spreaders halyards, doublers and tracks the total rig weight tends to go down only by 20%, with the sails aloft this % drops further.

Carbon fibre is still very much in its infancy in this field, fibre properties vary considerably manufacturer to manufacturer, the homogeneity of the finished product is poor, predicted strength is often not achieved. If you build heavy to allow for the problems you are back to the weight of an alloy masted rig.

The problem chasing stability with light rigs is the reduction in roll inertia. As eric knows but others may not be aware the roll inertia is proportional to the square of the distance from the roll axis. Therefore the rig has a huge effect on this imprortant seaworthiness factor.

Reducing the weight aloft leads to higher roll accelerations and higher dynamic loads, and a decrease in dynamic stability.

A yacht unable to carry a conventional rig due to stability requirements is chasing light displacement and speed as her main design criterion. I know there are various schools of thought on this issue, but my experience (and Marchaj's research ) says that comfort (read heavy and stable and safe) wins hands down in the cruising stakes.

The light displacement cruising/racing yacht is good fun for coastal cruising and if so designed may will benefit from a lighter carbon mast, but to retrofit a carbon mast on any reasonable design will be trendy, detrimental and expensive.

LOWCARBS heavy displacement double ender needing carbon fibre masts.................?

[sorenfdk]

The problem chasing stability with light rigs is the reduction in roll inertia. As eric knows but others may not be aware the roll inertia is proportional to the square of the distance from the roll axis. Therefore the rig has a huge effect on this imprortant seaworthiness factor.

To my mind, stability is THE single most important seaworthiness factor, so if you can gain some here and loose a little roll inertia, I think it's worth it.

And remember: The lighter rig will also reduce pitching - another important factor.

[Eric Sponberg]

The stability factor is a two-edged sword. Mike Johns is right in that a heavier mast adds to roll moment of inertia, and Sorenfdk is right in that a lighter mast reduces pitching. The high roll moment of inertia makes the boat harder to roll over in waves, although it will heel more in normal sailing conditions.

As for carbon fiber masts being trendy, detrimental, and expensive, well what's wrong with being trendy--Nothing. Will it be detrimental? Maybe, maybe not. It depends on the hull design and the location of the boat's center of gravity with either mast. Will it be expensive? Unfortunately, yes, the price of carbon is still high enough, and the labor required still specialized enough, that carbon spars are more expensive than aluminum ones.

Eric