Galion 22 conversion

  • 14 Sep 2017 08:12
    Reply # 5201606 on 5070195

    So, is the outside diameter 145, and not 150? Quite likely, as there is a Nedal tapered tube at this size. If so, I'm not so sure that it's a good idea to use it.

    If it is indeed a Nedal tube, is the next size up available, 165mm? That's the size that I have. If so, your troubles are over.

    Last modified: 14 Sep 2017 08:35 | Anonymous member
  • 14 Sep 2017 06:47
    Reply # 5194047 on 5070195

    David, you were indeed right - the flagpole has 2,8 meters of straight tube at the lower part. 

    However, the inner dimension is 140mm or a tad under it, so there is no way of inserting a 140mm tube in. And the next diameter available is 130mm. 

    Do I have other options to strengthen the lower part? A wooden inner mast?

    (Or getting a 140mm tube done to 139mm by a machinist, which I'm afraid will be expensive considering that I have to buy 6000mmm of the 140mm tube anyway. Is it possible to do this with home tools yourself?)

    Last modified: 14 Sep 2017 06:55 | Anonymous member
  • 13 Sep 2017 12:59
    Reply # 5094653 on 5094463
    David Tyler wrote:

    Generally, these flagpoles are parallel for a third to a half of their length, and then they start to taper, so I was thinking that at least a 4m length of internal sleeve was possible, if thought desirable.

    I had the impression that this pole is tapered all the way, but it seems that I have to ask the provider to be sure.
  • 13 Sep 2017 12:56
    Reply # 5094463 on 5070195

    Generally, these flagpoles are parallel for a third to a half of their length, and then they start to taper, so I was thinking that at least a 4m length of internal sleeve was possible, if thought desirable.

  • 13 Sep 2017 12:41
    Reply # 5093082 on 5070195
    Oh, you must mean inserting the straight tube inside the flagpole.

    The pole is tapered from 150mm to 60mm in 12 metres, which means about 7,5 mm per meter. A 140mm tube would fit only a tad more than a meter inside the pole, right?

  • 13 Sep 2017 12:29
    Reply # 5092062 on 5090709
    David Tyler wrote:

    Sorry, I don't think the flagpole is enough on its own. But if you were to take a length of 140 x 4 tube (maybe 3m long?), add a seal at each end that was guaranteed leakproof  to fill the 2.5mm gap (maybe some self adhesive foam rubber strip?) push it inside, drill a hole and pour in polyurethane casting resin, then I think you could end up with a very good mast. Strong and stiff at the bottom, light at the top.

    Hmm - and sorry. I'm sure it's me and not your text, but I don't seem to get the idea. Do you mean that this straight tube is inserted inside the flagpole or vice versa? Or something else?
  • 13 Sep 2017 12:11
    Reply # 5090709 on 5070195

    Sorry, I don't think the flagpole is enough on its own. But if you were to take a length of 140 x 4 tube (maybe 3m long?), add a seal at each end that was guaranteed leakproof  to fill the 2.5mm gap (maybe some self adhesive foam rubber strip?) push it inside, drill a hole and pour in polyurethane casting resin, then I think you could end up with a very good mast. Strong and stiff at the bottom, light at the top.

  • 13 Sep 2017 11:50
    Reply # 5089071 on 5070195
    It seems that there are tapered aluminium flagpoles available here. The length is 12m and the diameter ranges from 150mm to 60mm, but the wall thickness is only 2,5mm. I suppose this is not enough, even I could cut 2 meters off from the top?
  • 08 Sep 2017 23:51
    Reply # 5071230 on 5070816
    Anonymous member (Administrator)

    Jami,

    I agree with ueli lüthi  and his way of approaching mast dimensions. My rough way of estimating a boats max righting moment is to multiply its displacement with an estimated righting lever, which on your boat should not be more than 1/5 of the beam

    Mr= Disp x beam /5 = 1542kg x 2.21m / 5= 681kpm

    I would aim for a an aluminium (lower) mast with about twize the yield strength of the estimated righting moment. I try to keep the wall thickness no more than 4% of the diameter.

    I suggest you look up what tube is available between 12 and 15 cm, and what alloy (temper) is being used.

    The mast of my 2.15ton Ingeborg is 15 x 0.5cm, of 6082-T6 alloy, and that is slightly oversize for your lighter boat, me thinks (yield strength, My=2037kpm, weight 6.38kg/m).

    Arne

    Last modified: 09 Sep 2017 12:38 | Anonymous member (Administrator)
  • 08 Sep 2017 19:19
    Reply # 5070816 on 5070598
    Jami Jokinen wrote:

    …150/4 mm and 140/4 stuck together maybe? Or 140/4 and 130/4 if I would drop the SA to about 23 m2?

    hi jami

    the required mast dimension depends a lot more on the weight and the righting moment of the hull than on the sail area. (you will reduce the sail area in stronger winds anyway…)

    the mast should be able to heel your boat while jumping over steep waves – be it with more active sail area or with stronger winds.

    try this calculator to find an approximation to the righting moment of your boat and the breaking strength of different mast profiles.

    ueli

    Last modified: 09 Sep 2017 06:31 | Anonymous member
       " ...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