Wooden mast vs Alu mast...

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  • 06 Jun 2019 08:13
    Reply # 7558988 on 7550155
    Anonymous member (Administrator)

    Stefan

    I think the best (and by far the simplest) way of making an all-wooden mast of this size, is to make it from a trunk of tree. In Sweden there are plenty of good spruce-trees around, so if you have space for working with it (and the skills), then I recommend this method over building a mast from staves.

    Yes, 20% walls means 20% of the diameter. With a dug-out mast one can easily keep this factor constant, that is, with thinner walls further up the mast.

    With 20% wall thickness, the mast will be 36% lighter, and only marginally weaker.

    Arne


    Last modified: 06 Jun 2019 08:30 | Anonymous member (Administrator)
  • 06 Jun 2019 07:34
    Reply # 7558970 on 7550155

    Hello.

    And hello Arne in my neighbor contry

    Thank you for your answers. 

    I read through your link Arne. I believe I also can find it in the the Junkrigbook. 

    Have not got going yet but I’m aiming for next year so there is still time.

    I read it and I’m still confused  but it will come to me one day when I read it through a

    couple of times, I’m sure.

    It looks like the mast to your Johanna could be the one that can make it work. When you write 20% wall thickness is that 20% of the diameter?

    Is there’s any advantage in make it hollow or glue it?

    I have a feling that a dug out mast could be more flexible because it’s a dug out from a full tree trunk.

    And a glued mast get more stiff because it’s done of several strips of wood.

    I will see which way I go but I am very grateful of advise I can get and please let them come.


    best regards 

    StefanP

      


     

  • 05 Jun 2019 09:20
    Reply # 7556734 on 7550155
    Anonymous member (Administrator)

    Hi Stefan

    Both a wooden mast and an aluminium mast could work on your boat. A hollow spruce mast of 24cm diameter should do fine.

    Here is a description of how to make a wooden mast from a tree,
    and here is how you can make a two-piece aluminium-wood mast, or even a two-piece aluminium-aluminium mast.

    Your choice should be made based on what is most available, and what you have space, tools and skills to work with.

    Good luck!

    Arne

  • 04 Jun 2019 16:31
    Reply # 7555244 on 7550155

    Hello and Thanks for the replay. Dindnt think that far in the process but it’s worth thinking of

    Igot hold of a good wood worker that is interested in having a go at it.

    We will sit down a look in the junk rig book and see if we kan come up with a good plan.

    I think it will be a wood mast on this first prodject.


    best regards 


    StefanP

  • 04 Jun 2019 09:22
    Reply # 7554604 on 7550155

    Yes, Bertie is/was quite an unusual boat/rig. Here's a pic we took many moons ago in the outer harbour of Half Moon Bay, California. Very sad to hear the boat is no more - great to hear the owners were rescued!

    http://www.svtapatya.com/uploads/1/0/4/6/104632771/published/pict0184.jpg?1550831065

    There's a delightful little set of YouTube videos that the owners of Bertie made about going up to BC and meeting Allen Farrell and China Cloud. The first of the 3 is here

    https://www.youtube.com/watch?v=Zw6mdrcDL1o



    Last modified: 04 Jun 2019 09:40 | Anonymous member
  • 04 Jun 2019 08:21
    Reply # 7554559 on 7554164
    Jeremy wrote:

    Seems that this particular boat (SV Bertie) was merely knocked down in a squall, and was then flooded.


    Slightly off topic, but linked to masts.  A friend phoned me up today and while telling me why I need to open a Facebook account, mentioned that Bertie had been nearly capsized.  Some points worth mentioning: she is a Spray, which was not a self-righting vessel; she had rigging; apparently the mainsail was bowsed down.

    My friend tells me that the boat was hit by a 'white squall' while she was running, which involved an extreme windshift from E to W (or possibly the other way round: I don't quite recall).  One has to assume that the mainsail attempted to gybe and its boom being secured in place, made it impossible to do so, which resulted in the boat being knocked well over, its mast in the water.  As Jeremy says, the wooden mast probably saved their lives (apparently the owner had to swim for the EPIRB in the flooded interior - again, assuming I have the story correctly).

    I have had the unhappy experience of running on a boat with everything tied down and a situation arising that demanded an instant and extreme course alteration.  All I can say is that we were lucky that we were both on deck at the time and that the engine was reliable.  It was an extremely unpleasant and worrying few minutes and confirmed me in my already deeply-held conviction, that having to vang sails down is, essentially, unseamanlike.  This is my greatest objection to putting standing rigging on a junk rig; it makes it impossible to square out the mainsail; so while we are on the topic of how big and of what material the mast should be made, it is worth remembering that the fact that the sails on a junk are always capable of being gybed, makes this sort of accident less likely to happen.

  • 04 Jun 2019 01:37
    Reply # 7554164 on 7550155

    Recently (days ago) a wooden boat with a junk main'sl capsized off the east coast of USA - pics of the boat can be found on the net ( I found them on the wooden boat forum titled'wooden boat capsizes on last leg of circumnavigation'). Well in fact, the boat did not capsize, because the solid wooden mast floated, no doubt with help from the bamboo battens.

    Point of me bringing this up, is because I have previously chosen a wooden mast for this very reason, and think that if opting for an all alloy pole, it would be  worth aiming to achieve the same structural and buoyancy features as the traditional thing.

    Seems that this particular boat (SV Bertie) was merely knocked down in a squall, and was then flooded. However, in more severe sea conditions, a mast will need to resist greater stress on impact with the water. Wall thickness of the alloy is then critical and of course the wight and resilience of the material needs to be taken into account re resistance to fracture and subsequent loss of buoyancy.

    Additional diameter (in the lower part) would be advantageous in the case of ally, but this can then be a space robbing problem, so wood might prove to offer advantages in this respect.... although, a hybrid Ould offer the solution here?? 

  • 03 Jun 2019 03:19
    Reply # 7552274 on 7550155

    Hi Stefan,

    yes flag poles make good masts. If you can get hurricane rated poles they are the best as the base diameter can be somewhat reduced. If not then using a thinner wall pole slightly over length and cutting off the top ten percent or so works well. The major problem is supply, I have found that the best suppliers are in the USA and the cheapest in China and they also seem open to producing a custom spar to your specifications, ( have a look on Alibaba.com). Expect to pay as much again or more than the purchase price to get it delivered.

    All the best with the project. David.

  • 03 Jun 2019 00:28
    Reply # 7551946 on 7550155

    The boat I looking at is Bianca 27 long keel.

    3300 kilogram

    1400 in the keel. 

    Roughly length off the mast 10 meters. 

    Sail area is approximately 30 square meters.

    Flaggpool???

    Is the an option?

    didn't know they was that strong.

    The reason I begin to look at wood

    is that there is more options to get it repaired 

    if it breaks or gets damage.


    Best regards 


    StefanP

  • 02 Jun 2019 16:04
    Reply # 7550338 on 7550155
    Stefan Persson wrote:

    Anyone that know pros and cons if I say 

    Wood vs Alu...

    First question: Do you already have a preference? That is, do you have a ready supply of one material vs. the other? Do you find it easier working with one over the other? What size is the mast? How big is your pocket book? Do you like a "traditional" look? Are you building the mast yourself or having it made?

    Both materials have been used with success.

    I think also you would widen the question:

    • Include Hybrid
    • Grown wood
    • Laminated wood or built wood
    • pre-formed (engineered) aluminum mast
    • flagpole
    • constant diameter
    I would suggest reading the pdf on Hybrid Masts

    That would be a great start. Not that I think hybrid masts are the way you should go but because of the explanation of why the choices were made would be a good start in finding pros and cons.


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