Galion 22 conversion

  • 02 Nov 2017 19:31
    Reply # 5505579 on 5070195

    Poor Jami, I feel for you.  Marcus is making his mast with a 6m tube and (because he is sensitised to epoxy and can't work with it) he is having a carbon reinforced/glass fibre topmast made.  The guy making this, usually does carbon-fibre spinnaker poles.  You could possibly find on of the latter from a big boat second hand, and cut it down to fit?

    Do I recall that you can't get reasonable timber for a topmast?  That's probably the easiest route.

  • 02 Nov 2017 12:13
    Reply # 5500617 on 5070195

    I'll have to check with the supplier, if 6082 is available for all - if not right away, maybe before spring anyway :)


    The supplier unfortunately has informed only the weight of 140/5. It is 6 kg/m.

    Edit - I found info from another supplier:

    130/5 - 5,32 kg/m 
    140/5 - 5,75 kg/m (I have no idea why this is different than 140/5 above).

    Edit 2: I forgot the tapered flagpole. It is 145mm/2.5mm (parallel, 2.8m, 60mm at the top, total length 12m -> two meters could be cut off.) I don't know yet, whether this is T5 or T6, but David suspects it has to be T5.

    Last modified: 02 Nov 2017 13:57 | Anonymous member
  • 02 Nov 2017 11:34
    Reply # 5500289 on 5070195
    Anonymous member (Administrator)

    The 6082-T6 alloy would be my choice, with a yield strength of 250MPa (= 250Newton/sqmm = 2500kp/sqcm). The 6060-T6 alloy is 150MPa.

    Can all your suggested tubes be had in 6082-T6 and in 6m length?

    Arne

    PS: Do the tubes have a weight pr. meter in their data, so I don't have to calculate it?

    Last modified: 02 Nov 2017 11:56 | Anonymous member (Administrator)
  • 02 Nov 2017 11:20
    Reply # 5500169 on 5070195

    I quote the supplier: "It's either EN AW-6060 T6 , EN AW-6005A T6  or EN AW-6082 T6."

    Apparently it depends on the situation at the warehouse, the excact size of the tube and possibly on the time of the purchase (which one is available and when).

    Last modified: 02 Nov 2017 11:21 | Anonymous member
  • 02 Nov 2017 10:47
    Reply # 5499829 on 5499718
    Anonymous member (Administrator)
    Jami Jokinen wrote:

    The straight tubes are T6.  What does the double yield strength mean in case of straight 130-160 mm T6 tubes?

    (I'm a biologist and a journalist and a bit of a musician, not a technician or engineer, so this is all very complicated and strange to me...)

    Is it a 6060-T6 6082-T6 or some other alloy? If I know these, then I can calculate the bending strength of the tubes you are considering.

    Arne


  • 02 Nov 2017 10:34
    Reply # 5499718 on 5499102
    Arne Kverneland wrote:

    Jami,

    Do you know want alloy (temper) is used in those aluminium tubes?


    Now I have guesstimated the maximum stability of your boat to be about 715kpm (+/- 10%?). I would aim for a mast with a yield strength (bending moment) of about twice that.

    Arne


    The straight tubes are T6.  What does the double yield strength mean in case of straight 130-160 mm T6 tubes?

    (I'm a biologist and a journalist and a bit of a musician, not a technician or engineer, so this is all very complicated and strange to me...)
  • 02 Nov 2017 09:55
    Reply # 5499344 on 5070195
    Anonymous member (Administrator)

    David, I see.

    I was actually thinking about the hybrid aluminium-wood mast with a straight 6m tube in the lower end. I have found these to be easy to make,

    Arne

    Last modified: 15 Feb 2018 19:51 | Anonymous member (Administrator)
  • 02 Nov 2017 09:48
    Reply # 5499266 on 5070195

    Arne,

    Two problems:

    The temper of tapered tubes is only T5, as T6 is too hard to spin-taper.

    No mating size of tube is readily available.

  • 02 Nov 2017 09:33
    Reply # 5499102 on 5070195
    Anonymous member (Administrator)

    Jami,

    Do you know what alloy (temper) is used in those aluminium tubes?

    One factor I use to check when fitting a new mast on my boats, is its weight related to the weight of the boat. I try to keep the mast down on 3%, or better 2.5% of the boat.

    Now I have guesstimated the maximum stability of your boat to be about 715kpm (+/- 10%?). I would aim for a mast with a yield strength (bending moment) of about twice that. I could be willing to go a little below this and see what happens. The lovely thing with a freestanding tube mast is that one can easily see if it is struggling during sailing. This is visible long before any damage is done. If I felt uncomfortable with it, I would insert a 3-metre length of tube up the lower end of the mast. The highest stress in such an un-tapered mast is no doubt at deck level.

    Arne


    Last modified: 14 Jul 2018 09:18 | Anonymous member (Administrator)
  • 02 Nov 2017 08:54
    Reply # 5498727 on 5070195

    Ok, thanks. Sounds like an experiment that I don't want to make at sea.

    Unless I manage to find 165-170/3 tube, I will go with 140/5 then.

    For me it would be a lot easier to use a grp flagpole at the top 4 meters than making it from wood. I wonder if this will make the upper part of the mast too flexible?

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