Steel masts

Discussion in 'Sailboats' started by mikeny, Mar 26, 2017.

  1. mikeny
    Joined: May 2013
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    mikeny Junior Member

    I'm building a 37 ft Buehler was design for a wooden Mast I cut several Doug Fir Poles but he ended up with unsightly cracks and BS book he is using a 5 inch diameter tube with 1/8 inch wall. I need about 50 foot and it is stepped to the keel is wondering if anybody out there had experience
     
  2. gonzo
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    gonzo Senior Member

    You can use steel for a mast. It most likely will be heavier, and will require more maintenance to keep it from rusting. Checks on a fir mast are common and not a problem.
     
  3. mikeny
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    mikeny Junior Member

    Do you think it would be possible to router out the cracks and epoxy wood in them
     
  4. tspeer
    Joined: Feb 2002
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    tspeer Senior Member

    You might try building up the mast using birdsmouth staves. That would be lighter than a solid mast, and less likely to have cracks.
     
  5. mikeny
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    mikeny Junior Member

    I've looked at the bird's mouth Mast build I think it would be pretty hard to do by oneself
     
  6. Barry
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    Barry Senior Member

    Consider that the MAIN stresses in an unstayed mast are either compression or tension stresses induced from bending. A loose analogy is that there are parallel fibres running from the top of the mast to the bottom of the mast and that each fibre is continuous.

    The cracks, due to drying of the wood, run parallel to the fibres and do not hinder the ability of each fibre to carry a tension load.

    The opposite side of the mast, ie the compression side, it does not really matter if there are cracks there as the load and resultant stresses act vertically down. Note there is a slight consideration if under compression loading that the fibres, if you will allow the weak analogy, could separate, and reduce stability.

    But routing the crack out will in fact cut through the fibres and reduce the tension strength.

    If you are interested in aesthetics, ie the look, you could fill the cracks as they are now, without reducing the strength of the mast

    (Of course this is simplified as there will be some shear flow stresses due to bending acting vertically , some horizontal shear stresses due to the horizontal sail loading and some perpendicular to the mast shear stresses created from the weight of the mast when the boat is healed, perhaps some stress concentrations due to the fastening of the mast to the hull issues, but tension and compression will produce the highest loading in the mast)
     
  7. mikeny
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    mikeny Junior Member

    Does anybody have a recommendation to what would you would use for a filler I have tried linseed oil and window glazing it didn't work I tried several different kinds of caulking and it always pushes out when the weather changes and then shrinks back and leaves a crack again and looks bad the biggest cracks are more than a quarter of an inch I believe the Mast is strong enough and the weight is not that bad it has been on the north side of the building for ten years so it is well seasoned I have it supported in eight to ten places and I rotate it regularly
     
  8. gonzo
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    gonzo Senior Member

    Fillers will promote rot. Linseed oil is one of the worst culprits. Simply use deck and fence stain.
     
  9. mikeny
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    mikeny Junior Member

    I've soaked the inside of all the cracks wood deck stain flood product supposedly stops rot no issues of rot or fungus or anything like that yet just unsightly cracks the linseed oil and window glazing is something the old-timers used to do I was told by a rigger out of Port Townsend and so I gave it a try cleaned all that out and tried some logjam that they use in Montana on log houses that doesn't seem to be the answer either
     
  10. M&M Ovenden
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    M&M Ovenden Senior Member

    We will be building the wooden masts for our 50ft steel sailboat in the next few weeks; our masts will be laminated pine.
    We had considered taking down a few trees and standing them to dry but we know there will always be cracks and that it would annoy us. We have also (briefly) considered steel masts but we like the warmth of wood.
    We have already built multiple laminated masts so we are not getting into anything new. Advantage of laminated is that a defect in one plank does not cross through the whole pole. We are not using "select" grade wood to keep the cost down but we will be picking our planks so all the outside fibers is not free.
    Laminating a mast is not cheap, there is a cost to quality dried, planned lumber and the epoxy isnt also costs but you end up with an affordable quality stick.
    If you are interested in the build of the laminated mast, I will be posting about it on our website. We are now only waiting for our Canadian winter to end so temperature allows for the epoxy cure.
     
  11. mikeny
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    mikeny Junior Member

    Thank you I would like to follow your Construction it may be my next move I was thinking of just laminating fur and then shaping it after round. I have some 6 by 6 is from a 400 Year Old fir no Sapp and no heart plan on shaping my bow Sprint ,club-footed boom and my main boom like you I love the warmth of wood
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Grown masts will always check and show other defects. It's the nature of the beast and frankly unavoidable. The usual route is a rosin and beeswax mix, typically 50/50. Get the beeswax from a real bee keeper, otherwise you'll likely end up with a food grade that's not as good. You want pure beeswax, not paraffin. Rosin can be had from chemical supply shops or from cowboy supply outfits. It's cheap and you'll grind it to a fine powder with a mortar and pestle. I think Kirby paints has it too.

    The mixture is heated and troweled into the checks and cracks. When dry, scraped smooth. This will last some time (several years), but eventually will need to be dug out and replaced. This is an old school approuch to mask the natural habits of grown masts. It's also used over shallow "let" nail heads. It can be painted as well. Attempts at sealing these checks is futile and often promote other issues.

    Grown masts are for designs that can't ever consider leaving a dock, without at least 10 knots of wind and those, that will never sail particularly quickly, regardless of wind strength. This would be typical of a Buehler sail design. You could dramatically add to the stiffness of the Buehler design with a hollow mast. I've sailed on several and every single owner/builder has had the exact same thing to say about them: more ballast and more sail area, if they were to do it again. Most do add both eventually, so consider improving the SA/D, unless you plan on continuous trades efforts, with more area and adding more external (preferably) ballast. I'll assume you're building a Juna or Jenny. I've sailed a Juno,of which Juna is a close sister. It's a tender beast stock and under powered. Jenny is better in this regard, but slow with her area and both like to roll pretty good too.

    I'd strongly recommend a hollow mast. Use a mast diameter 10% bigger than the solid spec's and a 20% wall thickness. George's mast spec's are as over the top, as the rest of the boat's scantlings, so you'll be fine.
     
  13. mikeny
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    mikeny Junior Member

    Yes I'm building a Juna almost identical in measurements to the Atkins vixen Mast height overall weight with length waterline
     
  14. Nick.K
    Joined: May 2011
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    Nick.K Senior Member

    I have made several laminated masts and a few solid ones. I'd go for a laminated one. The big advantage is that you can eliminate the defects from the wood before you start but it also helps that you can build the mast from relatively small pieces of wood which makes it easier to source the material. I made one mast of about forty ft entirely from off-cuts of a planking job in the yard.
    It seems difficult when thinking about it but in reality it isn't.
    The two essential aids are a level set of supports and a string line.
    Set up the supports carefully with the stringline. We generally use beer kegs, two every ten ft with a 3ft block straddling on top. the blocks give space to lay out all the bits of wood pre-assembly and post assembly allows the mast to be rolled.

    Use the stringline to fair up the pieces pre assembly and then use it when gluing the pieces together to check the mast will be straight.

    Rounding and fairing the mast is a fairly similar process in any case whichever method you build by.
     

  15. mikeny
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    mikeny Junior Member

    Thanks Nick do you think one person could lay this that buy and sell and are you using tapered pieces my mass calls for 50 ft long 7 -1/2" tapering 3-1/2"
     
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