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Ingeborg, Arne's Marieholm IF

  • 14 Dec 2014 20:46
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    Reply # 3170070 on 3032430
    Deleted user

    Arne,

    I am going by the shipping weight listed by the manufacturer.  I will call them tomorrow and see if the actual pole weight is significantly less than the shipping weight. The length of the pole is listed as 33' (10.06m)

    I will post what I find for both thicknesses
  • 14 Dec 2014 20:28
    Quote
    Reply # 3170068 on 3032430
    Anonymous member (Administrator)

    Funny that, Dennis.

    Your data must either be wrong or my calculations must be off.

    I found that a 10m tube  152 x 4.77mm (constant diameter) should weigh around 60kg, while the same tube but with 1/4" wall (6.35mm) should be around 80kg.

    I suggest you calculate it yourself. I cannot see why a tapered pole should be heavier than a constant diameter tube.

    BTW, I reckon the density of aluminium to be 2.7kg/litre.

    Arne 

    Last modified: 15 Dec 2014 06:08 | Anonymous member (Administrator)
  • 14 Dec 2014 19:09
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    Reply # 3170029 on 3032430
    Deleted user

    Arne, Thanks for the guidelines.

     Those guidelines  would preclude use of the thicker pole for the IF as the dry weight of 10m pole is listed at 322#.  Unfortunately, even the 3/16" thick pole weighs in at 217# or 4.6%

    I might be able to get away with the thick pole if I go with the Frances (6,800#) which make the pole 4.7% of displacement.

    Either way, I will not be meeting your parameters unless I go fiberglass or carbon fiber
  • 14 Dec 2014 18:11
    Quote
    Reply # 3170005 on 3032430
    Anonymous member (Administrator)

    Dennis,
    the question is, what would that flagpole weigh after being cut down to max 10m? I have found that as long as the masts are not very tall and do not add more than 3% (better 2.5%) to the boat's displacement (sloop JR), you will be OK. The problem with heavier masts ( I once used one that was 5% of the boat's disp.) is mainly the added inertia in the pitch plane which will make the boat ride poorly over head sea. 

    Arne

    Last modified: 16 Dec 2014 10:30 | Anonymous member (Administrator)
  • 14 Dec 2014 18:07
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    Reply # 3170003 on 3032430
    Deleted user

    OOPS! that is another way of saying 3/16"

    Problem solved. 
  • 14 Dec 2014 17:45
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    Reply # 3169998 on 3032430
    Deleted user

    David,

    so far my choices are either that or 4.77mm.  A Goldilocks dilemma.
  • 14 Dec 2014 16:35
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    Reply # 3169991 on 3169983
    Anonymous member
    dennis gibbons wrote:

    Thanks David for the feedback.  Google searching has led me to a source of flagpole with a  6.35 mm wall thickness. While heavier, it may give me more of a safety factor.  Or am I overdoing it a bit?

    Overdoing it a bit. 5mm/3/16" is the right thickness to aim for.
  • 14 Dec 2014 16:17
    Quote
    Reply # 3169983 on 3032430
    Deleted user

    Thanks David for the feedback.  Google searching has led me to a source of flagpole with a  6.35 mm wall thickness. While heavier, it may give me more of a safety factor.  Or am i overdoing it a bit?
  • 14 Dec 2014 16:06
    Quote
    Reply # 3169980 on 3032430
    Anonymous member

    Dennis,

    6063T6 is fine. I have a 6063T6 tapered tubular mast, and after 80,000 miles, it shows no signs of weakness. Arne is using a 6"/150mm tube with wooden topmast on Ingeborg, so did Annie on Fantail, and I would say that this size is strong enough and just as importantly, stiff enough for a 26ft boat, whether it's 6061, 6082 or 6063.

    Arne's right about the hybrid mast-  it's the pragmatic way to get a mast, with no sacrifice of properties. Each part of the hybrid mast is easier to buy/transport/make than either a one piece alloy or wooden mast, and assembly on site is not difficult.

    Frances 26 - yes, a very sweet design, and would convert well, I think.
  • 14 Dec 2014 15:32
    Quote
    Reply # 3169978 on 3032430
    Deleted user

    That makes sense.

    Do you think the 6063-t6 may be too weak?

    If so, I will continue my mast search.

    BTW, while the IF is my number one choice, I have stumbled upon a Frances 26 which may be cheap enough for my budget. I think it would make a marvelous JR.
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