Carbon Mast/boom Project

[BobBill]

I read this thread and related links... How do I build a mast out of Carbon Fiber or glass

And, coupled with some other inf and, after reading the Krackenbait link material, decided that I might make complete mast or top section and a boom of carbon or carbon/glass matrix.

Why? To reduce top weight on a small dinghy and to do it for its own sake, if that makes sense.

The current mast is un-stayed Sitka flexible (as in old Finns) about 20 feet long. Boom is 10 feet. Both grooved for bolt rope sails, but can easily go with sleeve style used by Lasers, Force 5s and many new rigs.

Local university (Winona State U) has composite school, and contacted them to see if they might be interested in the project.

I am not super keen on the bag mechanics, and if I got the drift, this project may be completed without doing it, but until I contact someone at the school or one of you learned gents notes differences, I will wait on that decision.

Any comments, suggestions or advice?

[Doug Lord]

Originally Posted by BobBill

I read this thread and related links... How do I build a mast out of Carbon Fiber or glass

And, coupled with some other inf and, after reading the Krackenbait link material, decided that I might make complete mast or top section and a boom of carbon or carbon/glass matrix.

Why? To reduce top weight on a small dinghy and to do it for its own sake, if that makes sense.

The current mast is un stayed Stika flexible (as in old Finns) about 20 feet long. Boom is 10 feet. Both grooved for bolt rope sails, but can easily go with sleeve style used by Lasers, Force 5s and many new rigs.

Local university (Winona State U) has composite school, and contacted them to see if they might be interested in the project.

I am not super keen on the bag mechanics, and if I got the drift, this project may be completed without doing it, but until I contact someone at the school or one of you learned gents notes differences, I will wait on that decision.

Any comments, suggestions or advice?

========================
If it were me I'd get an engineer to figure out the laminate and a company that specializes in masts to do the work. It really is specialized work. On the other hand if you can afford the time and money(if it fails) why not try-you'll definitely learn something.

[michael pierzga]

Also remember that there are plenty of stock carbon dinghy mast profiles available. Many are of a quality that you will not be able to produce at home

[BobBill]

Michael, can you elucidate a bit more on what you mean. Profiles as to use as base or actual carbon masts?

I have my orig wood mast that I was going to use as mandrel or base...though I had not figured that part out yet.

Doug, I figured making a mast is about the same as making a graphite fishing rod, save the hardware reinforcements, flex or bend and size. I know that is oversimplification, however.

Mandrel, carbon/glass, resin, cure...and smooth.

Were not Shakespeare Wonder Rods simply glass wrapped around mandrels and tapped, and left unsanded, which gave them characteristic ridges?

Isn't mast similar, generally?

[Doug Lord]

Originally Posted by BobBill

Michael, can you elucidate a bit more on what you mean. Profiles as to use as base or actual carbon masts?

I have my orig wood mast that I was going to use as mandrel or base...though I had not figured that part out yet.

Doug, I figured making a mast is about the same as making a graphite fishing rod, save the hardware reinforcements, flex or bend and size. I know that is oversimplification, however.

Mandrel, carbon/glass, resin, cure...and smooth.

Were not Shakespeare Wonder Rods simply glass wrapped around mandrels and tapped, and left unsanded, which gave them characteristic ridges?

Isn't mast similar, generally?

===============
I can't imagine using glass and carbon in the same laminate though some of the tubes I buy have a thin glass veil as a finish. I think you'd be biting off more than you can chew BUT if you have the time and money it could be a great learning experience. There are numerous mast building/designing threads on this forum all over the place-I'd read each one before starting. (thats a lot of searching!) After you have done all this research( and I do mean after) you could pm Eric Sponberg if you have a question he hasn't already answered in one of the threads or in his mast section on his website(see below).
Also google carbon tubes: read how they are built-some with woven carbon, some with unidirectional carbon, some wrapped with carbon tow. I seriously doubt that you will come within 50% of matching the properties of a professionally built tube. You can buy a tube without the label "mast" on it a lot cheaper than if it is sold as a mast. You can create a taper by fitting one tube into another and you can get plastic sail track that can be glued to the carbon tube.

Read this: http://www.sponbergyachtdesign.com/Masts.htm

[BobBill]

Doug, The tube idea is intriguing. Will check it out.

[jim lee]

Pah! Go for it! If you really want it and put your mind to it, you can do it. The best carbon masts are built by humans. You're human right?

-jim lee

[BobBill]

Did some thinking on this. I decided to make top sections only, as these are simple tubes and maybe I can fashion (ala Doug L) out of pre made tubes or roll my own...reason is no fastener reinforcement needed.

Located one section already made for near $400 but that is not much of a challenge, so it seems one or two appropriate sized carbon top sections will be up come spring.

Sound like a plan?

[BobBill]

Not only found firms selling preformed carbon tubes, but a place that sells "socks" to use in layup...and they are not all that spendy.

[CatBuilder]

Anybody out there selling really large or custom elliptical tubes??

[Eric Sponberg]

I have found that the carbon socks that are available are really difficult to work with. The fibers snag everywhere as you try to slip one sock over the other on the mandrel. This completely ruins the sock.

As for large elliptical tubes--no one builds them on a production basis. There are not enough uses for them to justify a production setup. You've probably seen, too, that the most available round ones are pretty small diameters, and so cannot be used for anything other than on a small daysailer.

The trouble with carbon spars for larger boats is that they have to have large cross-sections, usually ones that taper along their length, at least partially; plus, they have to have varying wall thicknesses--thick wall down low, thin wall up high. This applies to both stayed and unstayed rigs. An extruded or pultruded tube does not fit the bill. As a result, only specialize spar builders have the equipment and expertise to build carbon fiber masts to the shapes, dimensions, and wall thicknesses required in sailboats. This does include custom shops--I can think of maybe half a dozen off the top of my head--who have the equipment and expertise to follow a well-done mast design.

Booms are in the same ballpark--although smaller than masts, they need special shapes and wall thicknesses tailored to the need at hand. This is a very specific application and not one to lend itself to production tube making.

Eric

[BobBill]

Thanks Eric. That is good to know.

This a not a large mast...slightly smaller than a Finn mast, unstayed, about 20 feet.

But, I have an alternate Force 5 spar set, in case the wood mast failed.

The wood orig is 73 vintage and though now with all cracks etc epoxy filled and reinforced with glass on forward side, I was being prudent.

I had thought to use the bottom section of the Force 5 mast and make a carbon spar to match the top two other sections...round and slight taper to tip that seems easy to use as mandrel.

Keeping the bottom metal section eliminates the need for reinforcement areas for gooseneck etc.

The spars are round, and just a bit larger OD than Laser spars.

I figured to use orig metal boom.

The total length of say one long carbon spar would be about 12 feet, or less, round, as I noted.

Be interesting sail, with lighter top, all else being equal.

Sock-wise, I had thought of rolling up on itself and soaking, then unrolling on mandrel...?

[Eric Sponberg]

Originally Posted by BobBill

Thanks Eric.

Sock-wise, I had thought of rolling up on itself and soaking, then unrolling on mandrel...?

I have not tried that, but knowing the stickiness of resin, I can imagine it is still going to pull and snag. However, who knows--maybe it will work.

You will find that socks are very expensive, ounce for ounce, and maybe that is not a concern for a small project. Can you buy in small enough quantities--that's usually another concern--you can end up with a lot of expensive left over. These are just typical concerns I have been faced with in the past.

Eric

[BobBill]

Eric, I understand.

Socks I looked at were not that expensive, but was only to save that link.


I have some time to work on the details, as I put the boat away and the cold north wind is descending on us here, sadly.


I am hoping it will be like making a graphite fishing rod, only larger...if this stuff had been around when I was younger, I would have jumped into the game long ago...

[BobBill]

BTW. Eric, I read the material you put up on carbon spars that DL offered. Thanks for the effort and the site. Very informative.