Freedom 40 Cat Ketch Junk Rig Conversion

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  • 18 Apr 2017 00:54
    Reply # 4757645 on 1424184

    Hey David - congrats  if it works out on the new boat! We also considered the 40AC, but turns out the bunks were just a tad short for me.  I got a PM from another member that is considering a F40 for conversion purposes, so possibly a crowed of us one day. 

    I like David T's hinges, Arne's barrel cut,  and Sebastian's (Tuchwerkstatt) shelf foot methods of creating camber and am headed for the latter presently.  But gosh, I've changed my mind before.  I do want to recommend Barry's Excel program if you are trying to quickly see what small or large changes change.  

    I've been messing with my sewing machines and am trying to figure out how to convert the living room into a sail loft. These are not small sails. Stand by for (slow) updates.  And feel free to ask any questions.

    Erik



  • 17 Apr 2017 07:36
    Reply # 4755109 on 1424184

    Greetings.

    I set out to purchase a Freedom 40', aft cockpit cat/ketch specifically for cambered junkrig conversion. Should my transaction close as expected, I'll have the boat transported across the US to the mouth of the Columbia river in the Pacific Northwest in a couple of weeks. 

    I'm very interested in this thread, and your progress aboard Raven, Erik. You've already addressed many of my concerns, and exposed more pitfalls which I'd not envisioned. I'm certain that I'll face some of my own within the evolution of my process, but I'm grateful for your considerable contribution, as well as those who've assisted your efforts. Thank you, one and all.

    I anticipate sailing for a spell with the original rig as designed, but I expect that the existing sails are well and truly ready for retirement. My plan is to commence my junkrig conversion in the fall, and perhaps benefit from your progress in the meantime.

    Again, thanks for sharing.

    ~Dave 

    Last modified: 17 Apr 2017 07:56 | Anonymous member
  • 20 Feb 2017 01:03
    Reply # 4618324 on 4617035
    Annie Hill wrote: I found a good fix to this problem was simply to fit two boom parrels - one that went aft around the mast and one that went forward around it.  With the boom more or less fixed, the rest to the sail didn't appear to be able to lurch around much, either.  And, of course, it doesn't add any friction when raising the sail.
    I've done the same on LC, it has worked well.
  • 19 Feb 2017 06:01
    Reply # 4617329 on 4617035
    Annie Hill wrote:
    David Tyler wrote:

    I use them, as they also damp down excessive fore and aft movement of the sail in a seaway, and they permit me to get away without a LHP.

    I found a good fix to this problem was simply to fit two boom parrels - one that went aft around the mast and one that went forward around it.  With the boom more or less fixed, the rest to the sail didn't appear to be able to lurch around much, either.  And, of course, it doesn't add any friction when raising the sail.
    Barry and Ann - thanks for the input.  As is, I've got the boom shorter than the battens by 5% which may help me make the Dmin of the lower sheet span fit.  As to stagger - I am hoping to be able to work with the batten parallels and possibly the THP or LHP to help with the reefing.  

    We are getting through some serious rain here.  Good time to keep working on all this stuff.

    Erik

  • 18 Feb 2017 23:19
    Reply # 4617035 on 4613081
    David Tyler wrote:

    I use them, as they also damp down excessive fore and aft movement of the sail in a seaway, and they permit me to get away without a LHP.

    I found a good fix to this problem was simply to fit two boom parrels - one that went aft around the mast and one that went forward around it.  With the boom more or less fixed, the rest to the sail didn't appear to be able to lurch around much, either.  And, of course, it doesn't add any friction when raising the sail.
  • 18 Feb 2017 21:25
    Reply # 4616971 on 4613440
    Erik and Evi Menzel Ivey wrote:I do think a batten angle greater than 10-11 degrees looks odd.  I would love to do less of an angle, but I need the rise to get the Dmin to work.

    I'm thinking that one way to "fix" that problem of two steep a batten angle looking odd would be to design the bottom panel different and having the remainder of the parallelogram panels normal with the batten angle a bit steeper.

    Arne does something like this by shortening the boom. You could also make the bottom panel wedge shaped so the next batten up has a steeper angle, or perhaps do both. The geometry is very solvable one way or the other.

    Now I'm starting to think...I just remembered that when I reef my sails, the sail bundle doesn't end up parallel with the battens above it anyways. These junk sails just seem to find their own set, despite my efforts to keep everything orderly!

  • 17 Feb 2017 02:20
    Reply # 4613440 on 1424184

    I better write something since I was the one to start this thread.  I've been thinking that David's guide on % camber/batten angle/P would only work for my planform if I do hinges. Else I will need to make batten and other parallels work since I do think a batten angle greater than 10-11 degrees looks odd.  I would love to do less of an angle, but I need the rise to get the Dmin to work. 

    I've been playing with the shelf-foot method of creating camber and spending too much time in front of the computer...


    Erik

  • 16 Feb 2017 22:05
    Reply # 4613160 on 4613081
    Anonymous member (Administrator)
    David Tyler wrote:

    ...

    But why build a problem into a sail, so that a fix has to be employed? Why not design the sail correctly in the first place? We aren't talking rocket science here, just recognising that a cambered panel should have a little bit shorter diagonal than a flat panel.


    My main reason to do it my way is that I never build less than 8% camber into any of the parallellogram panels, and I don't want the prescribed 14 degrees rise at the boom. On none of my sails, so far, have i needed to  add downhauls to get the sails down, not even on Johanna (48sqm)  and Ingeborg (35sqm), with their 5-part halyard. I therefore reckon that I don't have a friction problem with my half-long batten parrels, described below.

    And, as said; I don't bother with inventing problems. There are enough of them on other fronts in life.

    Arne

    Last modified: 16 Feb 2017 22:06 | Anonymous member (Administrator)
  • 16 Feb 2017 21:11
    Reply # 4613081 on 1424184

    I agree, Arne, that short, or semi-short batten parrels are a great way of making any sail, however designed, reef and furl satisfactorily. I use them, as they also damp down excessive fore and aft movement of the sail in a seaway, and they permit me to get away without a LHP. The downside is extra friction - acceptable in a small sail, not so much in a large sail.

    But why build a problem into a sail, so that a fix has to be employed? Why not design the sail correctly in the first place? We aren't talking rocket science here, just recognising that a cambered panel should have a little bit shorter diagonal than a flat panel.

  • 16 Feb 2017 20:38
    Reply # 4613043 on 4612071
    Arne Kverneland wrote:

    Another way of dealing with batten stagger

    Folks,

    frankly, I think you are about to invent a problem, or at least, turning a tiny problem into a big one. Having seen how easy it is to scare new or wannabe junkies, the matter of batten stagger can easily grow into a showstopper to them.

    KISS :-D
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