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Carbon fiber mast


Scott Dunsworth

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I read the post on carbon fiber mast. It doesn't look like a very difficult task to build one. I have a few questions for shine about building them.

1. The two masts for the Belhaven call for one 19+ feet and 17+ feet would we still build them the same diameter as for the Aluminum?

2. How do you mount hardware, sailtrack, head and etc.?

3. It looks like it would require quite a bit less labor than a fir mast but how would it compare in cost?

Scott

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Hi Scott .... I emailed Shine to make sure he sees this message. I know he visits the Main Forum, but I'm not sure he's in this forum very often.

I was wondering the same thing about carbon fiber. I don't know how you size it for the task, and was wondering if Graham had something on it too. You know, scantlings to use for carbon fiber verses aluminum?

The carbon fiber mast kits have the advantage of being easily shipped, and the builder can build it. For people who can't find the right aluminum alloy, it might make perfect sense.

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I wonder if Aerosleeves pricing is correct ... .they have 12.49 per YARD listed on their price sheet. I suspect that is supposed to be per foot, like the others. Shine's kit includes all the materials, so the cost seems about equivalent to me (14.71 a foot for the 17 foot mast).

Does anyone have any engineering data on these? I know Graham's boats specify a certain size aluminum in a certain alloy based on the design loads that can be expected. Any way to translate that to a certain diameter and thickness of carbon fiber mast?

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Yes, those prices are right in line with our kits. In our kits, the CF is sandwiched between two layers of a biaxial fiberglass sock. Also, the CF material on those sites are not exactly the same. Ours is a unidirectional material. Its not a secret by any means, but you do have to buy several thousand dollars worth to get a decent price. :shock:

We include the epoxy in the kits. We can also put in (at no additional cost) a post cure epoxy - phase 2 resin from system three. A couple hours at 140 degrees is all you need. We do not list it with the kit because post-curing could be scary to builders just wanting a small spar, but for the larger one is makes a lot of sense.

Joel

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Thanks for the info shine. The cost of the carbon fiber mast is cheaper than the one piece aluminum flag poles in 20 foot lengths. I found them locally. They where actually to thick at .125 unstead of .081 inch.

But I think I'll stay with the wood it comes to about $75 per mast for select douglas fir. Although a lot more work to build hollow. But my labor is the cheapest thing I have.

I will keep the fiber mast in mind for a core sound 15. I want to build one day with speed and lightness as the main quest.

Scott

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I wonder if Aerosleeves pricing is correct ... .they have 12.49 per YARD listed on their price sheet. I suspect that is supposed to be per foot' date=' like the others. Shine's kit includes all the materials, so the cost seems about equivalent to me (14.71 a foot for the 17 foot mast).

Does anyone have any engineering data on these? I know Graham's boats specify a certain size aluminum in a certain alloy based on the design loads that can be expected. Any way to translate that to a certain diameter and thickness of carbon fiber mast?[/quote']

I just wanted to clear up any confusion here - the prices listed on our site for biaxially woven fiberglass, carbon fiber, and carbon/kevlar hybrid sleeves are all per yard as stated. Carbon fiber sleeves start at $13.75 per yard rather than $12.49:

http://www.aerosleeves.com/order/?material=carbon

I would be happy to answer any other questions you have about our products.

Jeff Holman

Aerosleeves Sales

www.aerosleeves.com

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Ok, I don't know anything about this Aerosleeve stuff so I have to ask a question, probably dumb but here goes. How strong is it? I mean could you make a mast for a small sailboat like the mini-cup with it by putting it over thin aluminum irrigation pipe or 2" schedule 40 PVC pipe? Leave the pipe in the sleeve instead of removing it?

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But I think I'll stay with the wood it comes to about $75 per mast for select douglas fir. Although a lot more work to build hollow. But my labor is the cheapest thing I have.

Scott

Scott, I was under the impression that wood masts were not a good option for CS's because they were unstayed and would be to 'bendy". Am I mistaken??

Being a Wood boat nut I want my boat to have wood masts but I decided to go with alum and paint them so they weren't so ugly.

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Ok' date=' I don't know anything about this Aerosleeve stuff so I have to ask a question, probably dumb but here goes. How strong is it? I mean could you make a mast for a small sailboat like the mini-cup with it by putting it over thin aluminum irrigation pipe or 2" schedule 40 PVC pipe? Leave the pipe in the sleeve instead of removing it?[/quote']

You can definately apply the sleeves (single or multiple layers) over a irrigation/PVC pipe to stengthen it. If you aren't overly concerned about the weight of the finished mast, then this will provide the most strength and rigidity. Since the pipe is relatively rigid to start with (as compared to, say, a cardboard tube), the finished product won't flex at all and will take a lot of abuse (you could easily stand on it after applying a single layer).

If your looking to keep the mast as light as possible, you can also make a pure composite tube. You can do this easily by wrapping mylar around a madrel (the pvc pipe would do), then covering it with wax and buffing it. Once that's prepared, you can simply slide a single or muliple sleeves on the tube and apply epoxy. When it's dry, you can slide the mylar off of the mandrel and shouldn't have much trouble removing it from inside of your new tube. If you think you might do it this way, I'd recommend using at least one layer of fiberglass (for strength) and one of carbon fiber (for rigidity). Our tutorial has more detailed instructions, including pictures:

http://www.aerosleeves.com/tut.php

Let me know if I can answer any other questions. If you'd like to discuss the specific requirements of your project, feel free to send me a private message.

Jeff Holman

Aerosleeves Sales

www.aerosleeves.com

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I just wanted to clear up any confusion here - the prices listed on our site for biaxially woven fiberglass' date=' carbon fiber, and carbon/kevlar hybrid sleeves are all [b']per yard[/b] as stated. Carbon fiber sleeves start at $13.75 per yard rather than $12.49:

http://www.aerosleeves.com/order/?material=carbon

I would be happy to answer any other questions you have about our products.

Jeff Holman

Aerosleeves Sales

www.aerosleeves.com

Thanks for the clarification, Jeff! I should have dropped you guys a note that we were talking about the product (I usually do that to invite vendors who are inclined to pop in and answer questions). But I'm glad you found your way to us!

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But I think I'll stay with the wood it comes to about $75 per mast for select douglas fir. Although a lot more work to build hollow. But my labor is the cheapest thing I have.

Scott

Scott' date=' I was under the impression that wood masts were not a good option for CS's because they were unstayed and would be to 'bendy". Am I mistaken??

Being a Wood boat nut I want my boat to have wood masts but I decided to go with alum and paint them so they weren't so ugly.[/quote']

In all fairness, I would be interested in hearing any thoughts from Graham on this matter. One thought, and it may be another dumb thought and mental freeze, a black mast for a nicely trimed out cs? Or am I missing something? How does the composite fair over time with sun? I have not read a lot on the product, and have never used anything other than some Kevlar when talking "spaceage" products. :wink:

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Scott, what bothers me in this discusion, and finds me voicing some opposition, is that some are promoting an alternative to the plans. It is very critical , in a free standing mast, that it stays in tack, and in place. One thing we have had some problems with, is carbon fiber snapping in products under stress, becoming a sword so to speak. This bothers me when I see posts that promote this without some real information on some tests. As amateurs, testing is not that great in real time events, such as the demasting in Australia. There is a big difference in free standing strength and reinforcing strength. T

here is also a huge difference in quality control in the manufacturing of such parts in a at home garage setting, with even the best of materials, to achieve the same end results showing up in parts made in a regular plant. Hopefully, and in this particular case with this board, most designers will figure in a grace factor with a known product and in turn can deal with flaws and problems that do come up in some cases, with feed back from the consumer, at that time.

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I would like to add to what Oyster said. I like aluminum masts, especially in our smaller boats because they are light, strong, reliable and relatively inexpensive. A section of 6061-T6 whether made in USA, Australia or Europe will have similar properties and be consistent over it's length. While carbon is fantastic stuff, the mechanical properties of a home made spar can vary from great to dangerous. Carbon fiber comes in various grades and fiber sizes and weaves and when you add the home built variables like fiber orientation, wetout, quality of epoxy, mixing and cure and thickness. So, it can be seen, that there are numerous options for having a more expensive but less strong mast - and at best you have a more expensive mast that might be somewhat stronger and/or lighter.

For larger boats - say above 20 feet, the rewards of carbon start to improve - athough still subject to the above mentioned variables of home manufacture.

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Thanks for the insight, Graham.

The thing I'm concerned about more than anything is that there seems to be a lack of info on the relative strength of the carbon fiber mast. I'm sure there must be some engineering data somewhere that a person could use to determine what size of carbon fiber mast they would need to equal a mast of a certain cross section of aluminum.

Barring that, it looks like its another of those decisions a builder would have to make with some concern that his work might not be adequate.

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As was mentioned, the strength of carbon fiber will vary based on the application - for instance, the angle of the braid, type of epoxy used, proper layup, and the type of fiber used in the sleeve or cloth. I'm including some stength data below for our Toray T700-based carbon fiber sleeves that should give you a general ballpark if you're considering the use of carbon fiber reinforcement. For precise information, you'd be best off asking each individual manufacturer for test data.

These following values apply to a 45 degree braid angle; the change in strength at other braid angles is predictable - ask me if you're interested in such information.


  • Axial Modulus (psi) 3,500,000
    Transverse Modulus (psi) 3,500,000
    In-plane Shear Modulus (psi) 5,200,000
    Axial Tensile Strength (psi) 35,000
    Transverse Tensile Strength (psi) 35,000

Hope this helps.

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Frank, a rough rule of thumb for carbon fiber braid would be to use the same diameter as specified for the aluminum mast and increase the wall thickness by 50%. This is conservative and should come out at about 75% of the weight of aluminum. The thing to remember with carbon is that it has very little stretch so it is better to over design it a little. I would not go sailing with it until I load tested it.

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There's always risk in substituting materials like this. The mast is one area where failures under use are almost always "spectacular".

Not sure I'll risk it if I ever get that Spindrift going again. I may try making it into a nesting version now that I have my production boat (although my production boat is so small, the Spindrift may do better on a painter behind than nested ... unless it can fit in the companionway!)

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