S2 6.7 Junk Rig Conversion

  • 01 Nov 2018 22:52
    Reply # 6884907 on 6884609
    Anonymous wrote:
    Scott wrote:

    The answer is going to be "Don't do that!" but ... Is there one of these two that will clearly work better than the other if the sail panels are cut completely flat?

    The answer is going to be "Do do that!", because although we've said that it doesn't make much sense to make a flat sail these days, knowing all that we know now; you still want to find out for yourself.

    But, do it with a polytarp sail, so that you make a minimal investment in finding out what works and what doesn't. Cut your shape out of one big tarp, add some pockets very quickly, made out of the offcuts, and make a rolled tabling around the edges, not webbing (to save money). This sail should last a summer or two. Put your initial permanent investment of work and money into getting a tabernacle and mast into the boat.

    First, though, you'll have to decide on what kind of sailplan, in order to know where and how long the mast has to be.


    David,

    Thank you for the very well reasoned advice regarding a polytarp sail. I agree it makes sense for me to learn about flat sail performance at a lower cost and then later build the final sail with a quality long lasting material.

    I think I am on my own now. The Faintail sail, Arne's sail and the Weaverbird sail all seem to have different advantages. I find it harder to make a choice when all the options look good. 

    Somehow I will need to decide for myself what features are most important for the sailing I am likely to do. 

    Scott.

  • 01 Nov 2018 19:17
    Reply # 6884609 on 6883177
    Scott wrote:

    I will try to put the "tall tabernacle" out of my mind. Thank you for the response.

    Seems I am back to not knowing what to do, so I put the Fantail sail and the Weaverbird sail on top of the line drawing of the original rig. Maybe I should rig it so I can swap back and forth between the two? (A joke, of course).

    I think the answer is going to be "Don't do that!" but ... Is there one of these two that will clearly work better than the other if the sail panels are cut completely flat?

    Scott.


    The answer is going to be "Do do that!", because although we've said that it doesn't make much sense to make a flat sail these days, knowing all that we know now; you still want to find out for yourself.

    But, do it with a polytarp sail, so that you make a minimal investment in finding out what works and what doesn't. Cut your shape out of one big tarp, add some pockets very quickly, made out of the offcuts, and make a rolled tabling around the edges, not webbing (to save money). This sail should last a summer or two. Put your initial permanent investment of work and money into getting a tabernacle and mast into the boat.

    First, though, you'll have to decide on what kind of sailplan, in order to know where and how long the mast has to be. The Fantail planform will work better than others, as it adds some camber by the fiendishly cunning chinese method of allowing the upper, fanned panels to twist a little. These panels can be flat, even if, later, you come to realise that the lower panels can have and should have had some shape sewn into them. 

    Having said all that, later on when you've experienced a flat sail and got bored with sailing to windward slowly, you could do as I've one, and add camber by putting double cone hinges into the lower battens of a flat or near-flat sail. This way, you retain the one good thing that a flat sail has going for it: its docility.

  • 31 Oct 2018 22:08
    Reply # 6883208 on 6883186
    Anonymous member (Administrator)
    Annie Hill wrote
    I didn't have any more than the usual problems of the sheet fouling the leech of the sail.  I don't think there would be any advantage to lengthening to top sheeted batten.  

    Annie,

    it appears that your and my view on what is usual, is not the same. On the early sails I had, with a forward-leaning leech, sheet tangle was quite frequent when making long gybes. On the last three boats, i have kept the leech vertical or even leaning a bit aft, and on these there has been very few snags. In fact, for some reason I cannot explain, on my present Ingeborg I seem to get away with any sort of gybe without any sheet tangle. I do make batten 2 from top longer than the others since the leech of panel 3 leans forward.

    Arne


  • 31 Oct 2018 21:37
    Reply # 6883195 on 6872873
    Anonymous member (Administrator)

    Scott,

    sorry, but I couldn't resist the temptation, so I imported the Sailboatdata.com's sailplan and plonked one of my junkrigs on it. I ended up with a moderately tall sail with hopefully a not too tall mast (8.07m above wl.). See for yourself (batten length 3700mm).

    Arne

    PS: If you drop me a line, I'll mail you the .dxf file.


    Last modified: 31 Oct 2018 22:18 | Anonymous member (Administrator)
  • 31 Oct 2018 21:22
    Reply # 6883186 on 6882147
    Arne wrote:Scott,

    The fantail sail has proven that it works. Just take care and terminate the battens flush with the leech. This will minimise the sheet tangle. Would it be an idea to lengthen the top sheeted batten? Annie should be the right one to answer on this.

    Arne


    I didn't have any more than the usual problems of the sheet fouling the leech of the sail.  I don't think there would be any advantage to lengthening to top sheeted batten.  One thing, however, is worth noting with the fantail sail: the battens don't lie neatly along each other when it is reefed, unless you slack off the YHP.  Deeply reefed, the top batten tries to dive its forward end under the sail bundle.  I never felt too happy about not snugging up the YHP, but I'm not sure if this caution was justified.  Those more technically competent than I might like to comment on this.
  • 31 Oct 2018 20:59
    Reply # 6883177 on 6882763
    Anonymous wrote:
    Scott wrote:

    How tall can I make a tabernacle? 

    The top of the tabernacle should be just below the foot of the sail, so that the sail doesn't have to pass over the extra width as it is reefed and furled.

    I will try to put the "tall tabernacle" out of my mind. Thank you for the response.

    Seems I am back to not knowing what to do, so I put the Fantail sail and the Weaverbird sail on top of the line drawing of the original rig. Maybe I should rig it so I can swap back and forth between the two? (A joke, of course).

    I think the answer is going to be "Don't do that!" but ... Is there one of these two that will clearly work better than the other if the sail panels are cut completely flat?

    Scott.


    2 files
    Last modified: 31 Oct 2018 21:04 | Anonymous member
  • 31 Oct 2018 17:45
    Reply # 6882763 on 6882723
    Scott wrote:

    How tall can I make a tabernacle? Would having the hinge point 6 feet above the deck be at all possible? I am imagining the top of the tabernacle above one or two of the battens. That might allow me to lay the mast down without having an unreasonable length hanging over the stern. I have not seen anyone with a rig like this -- I imagine there might be a good reason.

    Thank you,

    Scott.

    The top of the tabernacle should be just below the foot of the sail, so that the sail doesn't have to pass over the extra width as it is reefed and furled. Even with the type of tabernacle that puts a hinge into the mast itself, with a tube that drops over the hinge to carry the bending load, it's not really practicable to have the hinge higher than that.

    When the mast has been lowered, it's not usually left in the tabernacle, but is commonly taken out and laid along the boat, perhaps resting on top of the tabernacle. 

  • 31 Oct 2018 17:30
    Reply # 6882723 on 6882236
    Anonymous wrote:

    Scott, 

    is there any strict restriction with respect to mast position and interior?

    Arne


    Arne,

    The major constraint is due to the very large trunk for the lifting keel. Right now there is just enough room to duck and waddle around the trunk on all sides. There is currently a compression post directly under the mast. If the aft side of the mast (tabernacle) is placed any further aft than the current compression post I think it will make the meager accommodations even less comfortable. I attached a drawing showing the keel trunk and compression post locations.

    I do not know what structural factors come into play with putting the mast through the cabin top instead of the fore-deck.

    David,

    I would really prefer to minimize the length of the mast. I would like to make it practical to trailer the boat regularly and use a tabernacle.  I have no doubt that the Weaverbird sail has all the advantages that you describe. It seems the trade off is a tall mast. I saved a copy of the Weaverbird CAD files. I will consider following this design.  Unfortunately I think it might not be trailer sailer friendly.


    How tall can I make a tabernacle? Would having the hinge point 6 feet above the deck be at all possible? I am imagining the top of the tabernacle above one or two of the battens. That might allow me to lay the mast down without having an unreasonable length hanging over the stern. I have not seen anyone with a rig like this -- I imagine there might be a good reason.

    Thank you,

    Scott.


    1 file
    Last modified: 31 Oct 2018 17:31 | Anonymous member
  • 31 Oct 2018 11:17
    Reply # 6882236 on 6872873
    Anonymous member (Administrator)

    Scott, 

    is there any strict restriction with respect to mast position and interior?

    Arne

  • 31 Oct 2018 10:13
    Reply # 6882159 on 6882147
    Arne wrote:
    Scott wrote:

     I think this fan sail design is the right way for me to go.

    Scott.

    Scott,

    The fantail sail has proven that it works. 

    Yes, it works, but it's not a universal rig, to be chosen without considering the alternatives. Annie decided she didn't like it very much. I sailed with it from NZ to Alaska, and decided I didn't like it as a big boat's rig. David Thatcher is still using it, satisfactorily.

    Just take care and terminate the battens flush with the leech. 

    Highly desirable on all junk sails.

    This will minimise the sheet tangle. Would it be an idea to lengthen the top sheeted batten? Annie should be the right one to answer on this.

    Or me. Or David Thatcher. We've all used this planform. The extended top sheeted batten is also highly desirable on all junk rigs (except the double port/starboard sheeted ones, of course).

    Arne


    Scott,
    Depending on accommodation constraints, you might like to consider my Weaverbird planform of sail, which is easier to use the the Fantail planform - fewer issues with helm balance off the wind, deep reefing, sailcloth stability and parrel loadings. The S2 6.7 has enough stability to carry a higher AR than the Fantail planform. On the other hand, the shorter mast of the Fantail planform may be of value, as you intend to trail the boat down to the slip to launch, meaning that a tabernacle is going to be useful.
    Last modified: 31 Oct 2018 13:09 | Anonymous member
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