Galion 22 conversion

  • 14 Mar 2018 09:23
    Reply # 5970879 on 5970870
    David,

    this is exactly what I was starting to fear. Ahh, the sail is coming along nicely - why can't the mast be a smooth project, too!?

    I still have to visit a supplier of aluminium lamp posts (and the Nedal 145/2.8 flagpole) and see the quality and sizes of their products.

    In this picture their non-tapered posts seem to have very nice and smooth transition zones. However, the alloy is T5. Could one live with this if the wall thickness and diameter would be enough - or does it mean a very heavy mast?

    Last modified: 14 Mar 2018 09:28 | Anonymous member
  • 14 Mar 2018 08:57
    Reply # 5970875 on 5070195
    Arne,

    I think both the 130/5 and 100/4 are 6060 T6.

  • 14 Mar 2018 08:28
    Reply # 5970870 on 5070195

    Yes, pourable polyurethane is a possibility, but the practicalities would take some thinking about. You would need to stand the tubes vertically, having made a setup that held the tubes concentrically and was guaranteed leak-proof at the lower end of the upper tube, and then be in a position, several metres off the ground, to mix and pour the compound. Not a trivial problem to solve, and so it would be a good idea to investigate having two rings turned from aluminium or hard plastic, to be screwed into place. Also non-trivial is making a smooth conical transition between the two diameters. I confess that I can't think of a satisfactory way of doing that, with only home workshop facilities.

    So I would continue to look at the one piece tapered tubes, both aluminium and GRP.

    Last modified: 14 Mar 2018 08:29 | Anonymous member
  • 14 Mar 2018 05:40
    Reply # 5970784 on 5070195

    Hmm, sounds doable, thanks.

    The 130/5 would leave a 10mm gap between itself and the 100/4. This would then be filled with polyurethane rubber as David suggests?


    Last modified: 14 Mar 2018 07:40 | Anonymous member
  • 13 Mar 2018 11:27
    Reply # 5968890 on 5070195
    Anonymous member (Administrator)

    Jami

    A mast from two tubes

    If you are now going for the AR=2.15 sail, then the total mast length should be 9.4m. That could be made from a 6m long 130/5mm lower section plus a 3.9m top section (3.4m + 0.5m bury). As basis for my calculations I have estimated a max righting moment of 681kpm. All bending strengths below are yield strengths, not ultimate breaking strength, which are much higher.

    The lower section:
    That 130 x 5mm tube should have a yield strength, Mb= 1505kpm, if the alloy is of 6082-T6 standard. Weight= 32kg.

    The 150 x 3mm tube should have an Mb=1313kpm if 6082-T6 alloy is used. Weight about 23kg.

    Although the thin-walled 1500mm tube looks tempting because of its light weight, the wall thickness makes me  a little worried that it can be dented and thus buckle in use. Handled with care, it should still be OK. I would then add a thick half-metre long grp wrapping at the partners.

    If only 6060-T6 alloy is available, then I would go for the 130 x 5mm tube at Mb=903kpm. This is only 130% of the estimated ultimate righting moment, but I would still try it, if the boat were mine. I would go sailing with it, at if it looked ok, I would carry on. If it looked to bend alarmingly near deck level, I would beef it up with a 2-3m inner tube. Remember, the Brits have for decades been using very thin masts from Needlespar, and these masts seem to have held for at least  20 years before coming down. A mast section of 13 x 5mm is generous compared to these masts.

    The upper section:
    At the joint, the bending moment will have been reduced to 40% or less of the moment at the partners. If you use 3.9m (3.4 + 0.5) of your old 100 x 4mm mast for top mast (Mb=710kpm  with 6082-T6 alloy), the joint should not be a weak point. The top mast should be 12.7kg.

    All in all the mast should end up at 45kg or 36kg. That is 2.8 or 2.3% of the boat’s displacement  -  very good numbers.

    Cheers, Arne


  • 12 Mar 2018 17:53
    Reply # 5967646 on 5070195
    It seems that I have to check the grp option again - even though I would like the al-mast more for the recyclability at the end of lifespan.

    The wind indicator grp-poles have these diameters:

    10m: 135 at the bottom, 65 at the top
    12m: 149 at the bottom, 65 at the top (2m would be cut off from top)

    I have sent a quote about the fiber direction and weight.

  • 12 Mar 2018 15:56
    Reply # 5967370 on 5593334
    Jami Jokinen wrote:

    The mast issue seems to stay problematic, because the availability of aluminium tubes in different sizes is quite limited, and lighting poles even more so.

    The options so far for a mast with total length of about 10 meters:

    1) 140/5mm al-tube, 6m plus a grp flagpole on top of this. Pros: easy to get, cheap. Cons: Heavy

    2) 145/2.8mm al-flagpole (2.8 meters parallel at the bottom part, total legth 12m -> 2m will be cut off at the top). Pros: Easy (not a hybrid) and light, Cons: Not strong enough. Can something be done?

    3) Grp flagpole (actually a pole for airport wind indicators, 10m or 12m for added strength (2m cut off)) with 7mm wall thickness. Pros: Easy, Cons: Heavy and possible installation problems (tapered all the way to the lower end)

    4) Something else?

    Is option 3) really out of the question? The density of GRP is about 2/3 the density of aluminium, so a 7mm GRP tube and a 5mm aluminium tube  should weigh about the same, at the same diameter. What is the diameter of the GRP pole? More importantly, what is the construction? We would want to see most of the fibres longitudinal or at a small angle to the axis. The full length taper wouldn't matter: with a cylindrical hole at the partners, wooden wedges would work well. 
  • 12 Mar 2018 15:14
    Reply # 5967322 on 5070195
    Due to responsibilities with home renovation (the family seems to be upset if forced to live without a toilet) the project has been set aside for a few weeks, but now I'm back on track. 

    Panels 5-7 done, panel 4 about 50%. After this I'll have to go back to drawing and make paper patterns for panels 1-3.

    At the same time the wintering boat seems a bit pathetic without a rig (BR rig sold), waiting for a new mast and JR sail.

    I still haven't solved the mast issue. 

    145/2.8mm T6 Nedal aluminium flagpole is option #1, if I just find myself believing that it is strong enough - with or without some reinforcing.

    I also got a new quote with 6m straight aluminium tubes with a bit more options than the previous ones:

    120/5, 120/8, 120/10, 130/5, 130/10, 150/5 mm.

    One of the other suppliers had also 150/3 mm.

    The problem with these is that I have no option to make a 4m wooden topmast, so I would have to use a smaller diameter al-tube or possibly a grp-flagpole.

    I still have the 100/4 mm tube left from my Joe 17. For economical and even more so for ecological reasons I would like to use this at the top.

    With the options above, I suppose this is out of question?

  • 16 Feb 2018 08:49
    Reply # 5740020 on 5070195
    Only with a "virtual batten", that is laying two parts on the floor to check that the highes go nicely like a zipper. 

    It might be wise to slip in a batten too, to see what the camber looks like. I might do this soon.

    Oh, I think I have finally decided on the name of my boat. It will probably be called "Inner peace". This is what I go for - and gain - while sailing solo.

    Last modified: 16 Feb 2018 08:55 | Anonymous member
  • 16 Feb 2018 08:26
    Reply # 5740015 on 5070195

    This is all looking good and strong, Jami. Have you tried assembling the two panels onto battens, to check that all is turning out as you'd planned? 

       " ...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