Primaat 24 conversion

  • 04 Nov 2019 13:53
    Reply # 8090544 on 7891576

    Don't worry, the sail will have some camber ! I'm interested in junk rig since I've discovered that junk rig goes well to windward thanks to camber.

    Anyway, I have to make a new rudder (the old one is broken, rotten plywood), I can make it bigger or with an endplate.

    I'l see if I can move forward the mast, or put more rake.

    Thank you for your help

    Thomas




  • 04 Nov 2019 09:57
    Reply # 8090335 on 7891576
    Anonymous member (Administrator)

    Thomas,

    I think the ideal would be to have the CE 10-20cm further forward. That said, if the boat were mine, and the mast had to sit where you have put it, I would give it a try as it is. A finkeel plus separate rudder design needs less lead than a full keel and integral rudder design.
    I would have a plan B ready: In case the boat turns out to have an annoying weather helm, I would start with fitting a big endplate to the existing rudder. I am pretty confident that this will help, but there is also a possible plan C: Make a new rudder and fit it to the transom.

    Good luck!

    Arne

    PS: I hope you make the sail with some camber in it.


  • 04 Nov 2019 08:45
    Reply # 8090309 on 7891576

    I'm struggling to find the right lead for my sail.

    If I follow the PJR rules, the 9% of WL forward the LCR including rudder, or the 6% abaft the BM CE, I find exactly the same place. I like it because it's the same place for the mast.

    But I read in the forum that we can go to 12, 15% of lead in order to prevent too heavy weatherhelm.

    Do you think I'm right with this sailplan ?

    Thanks

    Thomas


  • 11 Oct 2019 15:19
    Reply # 7928244 on 7891576

    Thank you for your reply, Arne and David.


    For the camber,  I think I prefer broadseam, for the simplicity of the batten.

  • 11 Oct 2019 14:28
    Reply # 7928188 on 7891576

    172 gsm is 5 oz/sq yd which is plenty strong enough. Are you proposing to use hinges, like Weaverbird? 

  • 11 Oct 2019 13:32
    Reply # 7928133 on 7891576
    Anonymous member (Administrator)

    Thomas, pardon for butting in here.
    Both proposed sailcloths will work, I but I would no doubt choose the lighter one at 172g/m2. This will inflate and set better in very light winds.

    Camber.
    More important is that you make the sail with camber in the panels. A sail with camber in it will perform a lot better than a flat one.

    I suggest you let David specify the construction of the cambered panels. The challenge is to make the sailmaker follow David’s instructions...


    Arne


  • 11 Oct 2019 12:59
    Reply # 7928070 on 7891576

    Weaverbird's sailplan with a seventh panel, 24m2. AR 2.26

    The mast is the same height as the original woodenmast, the weight should'nt be a problem.

    I've asked an estimate from a sailmaker, he propose Contender Sailcloth,  « Supercruise Coloured »  4,00 oz,  172 g/m2 or « Fibercon AP Coloured »  5.38 oz , 231 g/m² . 

    Do you think 172g/m2 will be enough for this sail ?

    Thanks !

  • 21 Sep 2019 18:53
    Reply # 7892577 on 7891576

    Thanks David, I've just scaled the sailplan to 24m², it gives something like that :


    The mast is very long, I'd liked to make a birdmouth wooden mast but perhaps it will be too heavy.
  • 21 Sep 2019 17:20
    Reply # 7892500 on 7891576

    Hello Thomas,

    Yes, I think I would want to put a Weaverbird sail on this boat. With the rudder well forward, it will be good to go with a high AR sail, and if you want to go for more than my 22 sq m, adding an extra panel will be the way to achieve that. If you can use the CAD drawing, I will send it to you.

  • 20 Sep 2019 20:30
    Message # 7891576

    Hello, I've just bought a Primaat 24 in need of restoration, without a rig, and of course I want to put a junk rig on her. She's a 24ft plywood boat, approximately 1.1t of displacement. Not sure exactely what type of rig I want, perhaps a weaverbird style, 24m² (the same area as the original rig).

    I have a bit of work before starting the mast step or the partner, but I've started to think about the conversion. I hope you will help me with the rig !

    Last modified: 08 Oct 2019 07:29 | Anonymous member
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