Rolled Carbon Mast

<< First  < Prev   1   2   Next >  Last >> 
  • 21 Jun 2021 15:21
    Reply # 10679491 on 10539767

    Here is another photo showing all the mast sections, with one mid section set up to use as a derrick to lift the lower mast.  Interestingly there doesn't seem to be an outer wrap... at least not visible here though in another photo it looks like there might be.  I know that on the Freedom masts, they have an outer wrapping that is apparently spiral wound glass to protect the carbon fiber from abrasion.


  • 19 Jun 2021 16:45
    Reply # 10669509 on 10539767

          I posted the bit on the rolled carbon mast not to advocate that everybody.... or anybody... go out and build one.   Weight reduction is of far more interest to me than to most folks... and of course to monohullers it's pretty much a non issue.    It is not something I'm likely to try.   I suspect that sailing up and down the US east coast, the Caribbean, and the Gulf, one could ferret out a used carbon fiber mast from a derelict Freedom or some other boat.  Note that one advantage of using the pultruded strips is that they could be tapered in a jig of some sort allowing the construction of a tapered mast easily, and as it was mentioned they would eliminate the problem of wetting out carbon fiber....  It's already done.

        Benjamin Franklin is falsely credited with the saying "watch your pennies and the dollars will take care of themselves"... The same can be said of ounces, pounds, and tons.  Below is a quote from the same forum:

    I spent this week mostly lightly grinding carbon strips for bonding.  Horrible job and a reason not to use the strips for masts.  However, it is quick, which is a reason for using them, along with cost.  

    Last modified: 19 Jun 2021 16:48 | Anonymous member
  • 18 Jun 2021 08:17
    Reply # 10659534 on 10539767

    Agreed: With sufficient skill and experience gained on previous projects, and sufficient tooling, equipment and infrastructure, it's possible to build a good carbon mast, for a racing mono- or multi-hull where the weight saving might justify the extra expense and work.

    But for a on-off mast for a cruising monohull, starting from zero experience, it makes no sense to try such a high-risk project, I submit. A little extra weight in the mast is actually a good thing, slowing the roll and adding to comfort. An aluminium mast is more suitable, lying somewhere between the extremes of a light carbon mast and a solid wood mast in its properties.

    Last modified: 18 Jun 2021 08:23 | Anonymous member
  • 17 Jun 2021 18:45
    Reply # 10656534 on 10539767

    Ketil's mast was built in a female mould, in two halves that were glued together. I use glass to keep the carbon were it has to be: straight up and down. Glass is +/_ 45 deg double bias. A layer of glass every 2mm of carbon thickness, plus inside and outside. 

    it is not a simple process to build a good carbon mast. You need a very tough epoxy that will seem brittle when the leftovers cure, as it has to deal with very a fibre that has very low elasticity. Also I always cure my masts in a very simple effective oven using a small boiler. 

    Rudolf

  • 17 Jun 2021 18:28
    Reply # 10656447 on 10539767

    I asked: Why didnt they ask Rudolf? Rudolf van den Brug build my mast. He is a member of the Association, and can easily be found. My mast is 12,25 cm high, 20 cm at the base, 12 cm at the top, and weigh in at 61 kg. It is being used in my X-99 in racing, and have sustained hard gybes, winds at 18 sek/m, surfing at 16 knots followed by a broach. The real advantage with a carbonfibremast is the ability to build the strenght where you need it. Heavy at the base, and lighter at the top. For me, carbonfibre wins hands down, period.

  • 16 Jun 2021 22:50
    Reply # 10651086 on 10539767
    Anonymous member (Administrator)

    If I remember correctly, Marie G's mast was built as two halves, using a female mould, and then the two halves were glued together. I think the mast was built in Holland.
    Hopefully, Ketil will add more details.
    Anyway, that mast appears to have worked perfectly well.

    Arne

    Last modified: 17 Jun 2021 09:19 | Anonymous member (Administrator)
  • 16 Jun 2021 20:48
    Reply # 10650461 on 10539767
    Ketil Greve has a carbon mast, it was made for him.  I recall that it was not made by a big company.  , more artisan than professional perhaps.  It would be interesting to know what process was used.
  • 16 Jun 2021 07:55
    Reply # 10646492 on 10539767

    My reply to all this armchair conjecture has to be:

    Don't try it. Don't even think about it!

    Howard, I made a carbon mast in pretty much the way you describe.  Even though my wire was stretched hard between uprights of  a steel framed factory  building, there was some sag. The process was long and difficult, and I ended up with a mast that was serviceable - and almost as stiff, light and strong as an aluminium mast would have been!! It ain't easy.

    When I reached Hawai'i, the battens that I made in Canada softened in the heat and broke. I had to retreat and quickly make wooden ones to continue to NZ. High temperature epoxy is a must, WEST ain't good enough.

    The 7 metre long battens that I made at David's place had to be hung vertically from a high point to set and initially cure, and still took a week to fully cure - they were still very soft and floppy after 24 hours. It was difficult to work fast enough to get the carbon onto the mandrel and wetted out within a reasonable time, and rushing it might explain the dry spots that caused later failures. Making a mast by this method would reduce me to a gibbering wreck. But if you want to try it, use high temperature, slow setting epoxy and make a post cure oven that can reach 180C. 

    So on the basis of my experience, I have to say: forget it. If you have access to a source of ready made carbon tubes such as carbonfibreprofiles.com in the UK, you can buy excellent tubes for battens and small yards - why would you even try to make your own?

    For masts the cost and the risk of failure are at a very high level. Forget it. Make a hybrid aluminium/timber mast, if you can't source a tapered aluminium lamp post or flagpole.

  • 16 Jun 2021 02:20
    Reply # 10645318 on 10643941
    Anonymous wrote:

    David Tyler made up a set of carbon battens, and a carbon yard for Tystie when he was staying at our place a few years ago. These battens were made out of double bias carbon sleeves stretched longitudinally over a mandrel, which produced almost longitudinal fibers.

    ...

    So I wonder whether the same carbon sleeves could be used to construct a carbon mast, but the sleeves are still quite expensive to purchase, and this method would not allow for taper.


    if they can be stretched or not, it would seem that varying the a mount of stretch from one end to the other would result in a taper. Of course a form would be required and probably calculating the fiber angle for various diameters. The problem might be that the widest part might be weaker rather than stronger, but if various layers use different sizes of sleeves that may not be a problem. The biggest sleeve may need to be very large to obtain almost longitudinal fibers. The question would remain, cost to weight/strength and windage.
  • 15 Jun 2021 20:36
    Reply # 10643941 on 10642756
    Howard wrote:

       It would be a time consuming and expensive process, but nothing compared to the cost of buying a factory made mast.    I'm not enthusiastic about the telescoping mast being built with straight sections. It's main virtue is that the construction is simple.   I'm not sure how one would extend and retract it.... looks complex to me.   


                                                     H.W.


    It seems that the processes to build a DIY carbon mast to be almost not worth the effort over the more conventional mast construction methods, especially the system which has now been used with success by some builders such as Annie, that is an aluminum lower mast with a timber constructed top mast sleeved into the lower section. I have been working with carbon fiber quite a lot recently making up fittings for my little catamaran. It is difficult to wet out thoroughly, which is not so much a problem on small fittings, but could be catastrophic on a mast resulting in resin starvation in part of the mast, which will of course result in mast failure. The correct way to construct items from carbon fiber is to use either vacuum bagging, or compression moulding to ensure thorough and even wet-out of the cloth.

    David Tyler made up a set of carbon battens, and a carbon yard for Tystie when he was staying at our place a few years ago. These battens were made out of double bias carbon sleeves stretched longitudinally over a mandrel, which produced almost longitudinal fibers. The mandrel was removed from the cured battens using our four wheel drive SUV, so it was real farmyard boatbuilding. David had some failures with his set of battens on Tystie due to dry spots in the lay up, but there have been no failures on the battens for Footprints after 9 years of use, and numerous hard gybes. Although the battens on Footprints were of a larger diameter than the ones on Tystie, so that may have improved their strength.

    So I wonder whether the same carbon sleeves could be used to construct a carbon mast, but the sleeves are still quite expensive to purchase, and this method would not allow for taper.

    I have some friends who successfully built freestanding carbon wing masts for their 56 foot catamaran. That was a DIY job and has been very successful with the masts still standing after 18 years and the catamaran having made many ocean crossings and spent the New Zealand summers as a charter yacht. These masts were made inside longitudinal female moulds with a moulded flange on the front and back of each half. Then when both sides of the mast were completed the two halves were glued together along the flanges. The layup of these masts was engineer designed. But I wonder whether this method could work for a junk mast as a taper could be achieved. So that is two half moulds, lay up each side of the mast from longitudinal carbon fiber, and then glue the two halves together. But once again it would be best to have the specifications of the layup engineer designed to achieve the correct layup for the required strength, otherwise there is a good chance of a mast breakage.

    Even using this method it would be well worth doing a careful cost/benefit analysis because I think the cost of carbon and resin for say a 9 meter length carbon mast could quite easily exceed the cost of materials to build an aluminum and timber composite mast, and so if there was no significant gain in weight reduction, and guaranteed strength, then it probably is not worth the effort and expense.,


<< First  < Prev   1   2   Next >  Last >> 
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software