Advice, please: new mast for Seablossom

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  • 22 Jan 2012 17:52
    Reply # 804765 on 788093

    Thank you Arne,

    As normal, the answer is right beside me on Storhaug. Now to get that translated to carbonfibre. I wish a mast between 18 and 22 cm diameter at the partner, wall thickness is probably according to the manufacturing process. 5 tonns pr meter, quite impressive. No wonder they can take a beating.

     

  • 21 Jan 2012 23:25
    Reply # 804428 on 804257
    Anonymous member (Administrator)
    Ketil Greve wrote:

    Thank you,

    I have been contacted by a Duch builder in carbonfibre. The biggest problem is to get a good calculation of what is needed. Most engineers talk about heeling forces, but I think that the biggest bending forces occur while beating agaist the waves. Some of the sudden stops experienced banging into a wave, can really shift loose items inside the boat.


    Ketil, how about using the strength of the present masts of Johanna and Edmond D. as references? If my calculations are right, their 25cm spruce masts have a breaking strength of around 6100kpm. Your new X-99 will be a bit lighter, but the mast will be taller and you will race it. What about 5000kpm? Five tons on one meter lever  -  after all that is quite a bit on a boat weighing less than 3 tons.

    Just a thought.

    Arne

  • 21 Jan 2012 18:36
    Reply # 804257 on 788093

    Thank you,

    I have been contacted by a Duch builder in carbonfibre. The biggest problem is to get a good calculation of what is needed. Most engineers talk about heeling forces, but I think that the biggest bending forces occur while beating agaist the waves. Some of the sudden stops experienced banging into a wave, can really shift loose items inside the boat.

  • 21 Jan 2012 03:43
    Reply # 803956 on 788093
    When I talked to these people about a free-standing mast they didn't even flinch.
    http://www.fortecarbon.com/mar_masts.html
  • 18 Jan 2012 19:33
    Reply # 801906 on 801203
    Jeff McFadden wrote:
    Ketil Greve wrote:

    This being a mast thread, does anyone out here have experience with carbon fibre? Everybody telling me it is far out pricewise, but I recon I can have one made in the region of 4000- 6000 GBP. The problem is wall thickness. As no compression loads is present, I can use spun tubes, either standard, glued in steps, or a tapered pole aprx. 13 meter high.

    Ketil 


    Ketil,
    I spoke with a company experienced in making carbon fiber masts, and of memory serves me right (which alas is not always the case) I could have had a carbon mast made for Seablossom (36' overall length) for about $5,000 US, far less than your guesstimate here. Do you want me to dig around and see if I can find their URL again?


    Hi Jeff,

    Yes please. I have found a few companies that manufacture carbon spars, but no one that knows anything about free standing mast, exept for an engineer named Stromberg. As an engineer he "must" have the boats heeling resistance to calculate the mast wich is fine if you have a competition to win with a corresponding budget to suit. I may ask for adwise though, it is the answer that costs money.  

  • 18 Jan 2012 08:00
    Reply # 801528 on 801060
    Ketil Greve wrote:

    Dear Annie,

    Being born in 1946, this is probably (I keep telling my wife) the last serious fling I will undertake.

     


    Yeah, right!  But totally the correct attitude.  I hate it when people start asking me if I've 'thought about the resale value'.  Who cares?  I may not be here to re-sell anyway!

    But I have come to realise that - astonishingly - not everyone thinks like me.

    I hope the bureaucrats allow your Viking funeral!!  Some time in the dim and distant future.
  • 17 Jan 2012 22:53
    Reply # 801203 on 800253
    Ketil Greve wrote:

    This being a mast thread, does anyone out here have experience with carbon fibre? Everybody telling me it is far out pricewise, but I recon I can have one made in the region of 4000- 6000 GBP. The problem is wall thickness. As no compression loads is present, I can use spun tubes, either standard, glued in steps, or a tapered pole aprx. 13 meter high.

    Ketil 


    Ketil,
    I spoke with a company experienced in making carbon fiber masts, and of memory serves me right (which alas is not always the case) I could have had a carbon mast made for Seablossom (36' overall length) for about $5,000 US, far less than your guesstimate here. Do you want me to dig around and see if I can find their URL again?
  • 17 Jan 2012 19:03
    Reply # 801060 on 788093

    Dear Annie,

    Being born in 1946, this is probably (I keep telling my wife) the last serious fling I will undertake. Looking at gravestones, one can clearly see peoples vanity. I hope to convince my daughtes to give me a Viking funeral, with food, weaponry and a few frilles, shove the boat from the shores with a fire set to it. The mast would be a perfect, erect, strong and durable gravestone: Here lies Ketil, dreamchaser. Sic transit gloria Mundi.

     

  • 17 Jan 2012 08:07
    Reply # 800774 on 800253
    Ketil Greve wrote:

    I recon I can have one made in the region of 4000- 6000 GBP.

    I don't know what boats cost in Norway - but that sounds like a large proportion of the boat's value.  If you intend to keep her forever, then it isn't an issue, but if you consider getting your investment back when you sell, it may prove an expensive decision
  • 16 Jan 2012 19:49
    Reply # 800266 on 788093
    Jeff,

    Long (really long) scarf joints have been used for ages, to replace damaged wood with new, and the result can be as good as new. Likewise a new mast can be made of many pieces of shorter wood. 

    Uniformity in the material is important, especially about the partners! Lumps of epoxy bog, or massive glass replacing wood fibre, won't help the mast - it wants to flex smoothly, or break at a discontinuity.

    SeaBlossom's nicked-up timber mast can be repaired. A little 'mast money' spent consulting with a sparmaker to plan the job would be reassuring and well worth it. 

    I'd suggest restoring the wooden spar first. After doing a careful job on the timber repair, you can add insurance with unidirectional fibre reinforcement, gradually thinning it above and below the partners. (Glass, not carbon. Last layer double-bias or woven, not uni.) It's not a difficult process.

    Cheers,
    Kurt

    PS - Since carbon was just mentioned in the post above, I'll clarify. 
    Proper carbon masts are great. Carbon to reinforce timber is tricky, because it's so much stiffer. Too much carbon concentrates stress in the adjacent wood; too little and the carbon may fail when the wood flexes, over-stressing and breaking the timber at that point. Glass is more like wood, so it avoids such extremes.

    Last modified: 16 Jan 2012 20:18 | Anonymous member
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