Red Fox Vision Conversion

<< First  < Prev   1   2   Next >  Last >> 
  • 13 Feb 2017 20:56
    Reply # 4607286 on 4571968
    Anonymous member (Administrator)

    Annie,

    I can see your point, in particalar about the fore-mast of a schooner. When running before in a 2-sail rig, is seems that the aft sail produces a lot of eddies which try to gybe the foresail back and forth, as on a Bermuda sloop. We did give the foremast on the schooner Samson, in Stavanger, some serious forward rake just to minimise this problem when running. The forward rake both increased the distance from the mainsail, and the weight helped as well. That foresail, with very stout battens, could even be squared out a  bit beyond 90 degrees, which let us broad-reach with the foresail sailing by the lee, kind of.

    Arne

    PS: In Chris' case, he wanted to keep the fore hatch, so I was not free to choose.

    PPS: There are a number of Freedom boats in JRA: I wonder what they have done to their masts when they converted from Bermuda cats to JR. Did they re-step their masts?

    Last modified: 14 Feb 2017 11:13 | Anonymous member (Administrator)
  • 13 Feb 2017 20:17
    Reply # 4607218 on 4606382
    Arne Kverneland wrote:

    Annie, which boats with JR have you actually sailed with two degrees aft mast rake? You sailed half-way to the moon in Badger (plumb masts?). Was that so bad?

    There will be a bit difference, of course, but I cannot see that a couple of degrees aft rake needs to be a show-stopper. Second-best - and theoretically wrong - options are often good enough. Keeping the sail, yard, battens and boom as light as possible helps, though.

    Arne

    Early on we realised that we'd made a mistake putting both masts vertical and forced some rake into Badger's foremast.  We could have done with more, but it certainly made a difference, particularly when running wing and wong.

    I'm not suggested that rake aft or plumb masts are a show stopper, but if you are starting from scratch and can put some forward rake in the mast, you might be happy that you did.  Of course, your chosen cruising ground makes a big difference, but often N Island summer days start with very light winds that increase to a pleasant sea breeze.  With on onshore swell bouncing off the shoreline, you get a very sloppy sea and with very light wind, the sail will want to flop around.  Hence my desire for a raked mast.  If you rarely encounter these conditions, then you'll probably wonder what I'm fussing about.


  • 13 Feb 2017 12:04
    Reply # 4606441 on 4605694
    Arne Kverneland wrote:

    Ueli
    Have you actually experienced this problem or are you just worried? 

    just worried! 
    I once had an 18’ dinghy, Broremann (below). The second JR mast I fitted in 2011 had between 1 and 2° aft rake, I guess. Only in dead calm did the sail ‘self-centre’. In even the lightest wind, the sail would fly and never give any problems.
    you may be right, as usual.
    i have only a 1:5 model of the sail for my own conversion and held it with different rakes – no real world experience.

    ueli

    Last modified: 13 Feb 2017 12:05 | Anonymous member
  • 13 Feb 2017 10:11
    Reply # 4606382 on 4571968
    Anonymous member (Administrator)

    Annie, which boats with JR have you actually sailed with two degrees aft mast rake? You sailed half-way to the moon in Badger (plumb masts?). Was that so bad?

    There will be a bit difference, of course, but I cannot see that a couple of degrees aft rake needs to be a show-stopper. Second-best - and theoretically wrong - options are often good enough. Keeping the sail, yard, battens and boom as light as possible helps, though.

    Arne

    Last modified: 13 Feb 2017 17:59 | Anonymous member (Administrator)
  • 13 Feb 2017 06:43
    Reply # 4606213 on 4571968
    Personally, I'd always include some forward rake.  The very washes that Arne mentions are part of the reason. In light winds, when a big wash throws the boat about, the forward raking mast will tend to help the sail stay set.  LIkewise, a forward rake helps keep the sail asleep when running in light winds and a sloppy sea.
  • 12 Feb 2017 20:58
    Reply # 4605727 on 4571968

    I have no worries with an aft raked mast having owned a Colvic 28 with a 48osq ft low aspect sail. The mast had a considerable aft rake noticed by me but not the sail.

  • 12 Feb 2017 20:47
    Reply # 4605694 on 4571968
    Anonymous member (Administrator)

    Ueli
    Have you actually experienced this problem or are you just worried?

    I once had an 18’ dinghy, Broremann (below). The second JR mast I fitted in 2011 had between 1 and 2° aft rake, I guess. Only in dead calm did the sail ‘self-centre’. In even the lightest wind, the sail would fly and never give any problems.

     

    Imagine the weight of sail (32sqm), yard and battens of Chris’ boat to be around 40kg. Since sine 2° is about 1:29, the wind force needed to hold the squared out sail from falling aft, should be around 40kg : 29 = 1.4kp, at most. That isn’t much to ask for from a 32sqm sail. I bet the forces from rocking and rolling in the stern waves from passing gin palaces will contribute a lot more to gybe the boat.

    Arne


    Last modified: 12 Feb 2017 20:48 | Anonymous member (Administrator)
  • 12 Feb 2017 17:44
    Reply # 4605536 on 4571968

    i wouldn't like the idea of an aft-raked mast with a low balanced sail.

    in light winds the sail will tend to fall down to the centerline of the boat.

    with the higher balance of a split rig this might be tolerable – but then you could stay behind the hatch anyway…

    ueli

    Last modified: 12 Feb 2017 17:46 | Anonymous member
  • 12 Feb 2017 09:44
    Reply # 4605084 on 4571968
    Anonymous member (Administrator)

    Yes, David,
    our thinking about shifting the CP aft by moving the hinges, and thus max camber point aft, is identical. I have asked Chris to read about my hinged battens in JRA Newsletter 24. I found that my symmetric hinge-camber on Malena added some weather helm, compared to when the same sail was flat. When I made the cambered panel sail, with max camber  about 35% from the luff, it initially produced a lee helm. After pulling the sail aft, the balance was put right again.

    Arne


    Last modified: 12 Feb 2017 20:58 | Anonymous member (Administrator)
  • 12 Feb 2017 09:25
    Reply # 4605077 on 4571968

    Seeing the the Sunbird 80s sail right next to the Johanna sail is interesting; the latter is obviously an advance in JR design. If economics and practicalities could be put to one side, I'd put a forward-raked mast where the forehatch is, and make a more modern design of sail.

    I had the same issue to think about with Weaverbird's  mast, risking too much lead if I put the mast forward of the forehatch. It's turned out fine, though, the helm is neutral. My new battens have the second hinge placed further aft, in an attempt to move the actual (rather than geometric) CE further aft and add a little weather helm. Maybe the Sunbird 80s sail can be used with a similar placement of hinges.

<< First  < Prev   1   2   Next >  Last >> 
       " ...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