Elizabethan Conversion

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  • 16 Dec 2016 13:51
    Reply # 4463265 on 4458199

    Colin,

    Love your clever way of finding the CLR with a piece of string.  Guess the some can be done to find the CE of the sail, if the wind was perpendicular to the boat.

    I think I am correct in saying: this method, as with balancing cut-outs  finds the static CLR / CE.  With a low aspect keel the CLR underway is actually much further forward.  Same for a low aspect rig, so perhaps one cancels the other.  Though mixing a low aspect keel and a high aspect rig (or visa-versa) may lead to misinformation.

  • 16 Dec 2016 10:40
    Reply # 4463075 on 4462283
    Deleted user
    Colin King wrote:...the Jr sail's Center of Effort will be lower than the Bermuda rig CE

    I would be surprised to find that the CE of any quadrilateral sail was lower than that of a triangular rig of an equivalent area. Simple geometry dictates that it must be higher.

    On my Sea Rover the CE is 14' 3" above partners - that of the original Bermudan rig around 11' above. Admittedly the JR is larger, but even scaled to the same area it would be well above that of the Bermudan rig.

    I believe the aspect ratio of the quadrilateral sail would have to be well below 1 before the CEs approach the same height.

    Chris

    Last modified: 16 Dec 2016 11:02 | Deleted user
  • 15 Dec 2016 23:44
    Reply # 4462283 on 4458199
    Deleted user

    James, Be not discouraged,

    If you do not have a drawing of the underwater profile of your boat you can still get the information you need to make a new sail-plan. The bit of information you need to know is the point on the centerline of the boat around which the boat turns (the CLR). For a clear discussion of the problem see https://forums.paddling.com/discussion/1452776/the-center-of-lateral-resistance The discussion there concerns canoes but is applicable to all sizes of vessels.


    In the case of a yacht, the CLR can be found by pushing the boat sideways away from a dock some 8 to 10 feet then using a single line to pull it back toward he dock. By moving the pulling point fore and aft along the centerline of the boat one can find the for and aft balance point of the boat. That point is the CLR.


    If you follow Arne's system of locating the CE of the new sail-plan on the same fore and aft line as the previous sail-plan (the Jr sail's Center of Effort will be lower than the Bermuda rig CE) the new JR mast position can be found. Luckily, it is within the tradition of JR masts to be canted fore-and-aft to suit the needs of the accommodation plan. And that is another plus for JR.

    Colin King

  • 14 Dec 2016 20:08
    Reply # 4460153 on 4458199
    James Lovett wrote:

    Apologies first of all as I am sure I have missed the obvious somewhere on the site, but I am considering my first conversion to junk rig and I'm not sure where to start and with whom. I'm practical but not ready to DIY it yet, so should I be looking at a designer first to come up with a plan of what work would need to be carried out to create the new rig and if it was even possible on my boat (Elizabethan 31 centre cockpit ketch). Just a nod in the right direction would be most appreciated.


    James, it's really quite straightforward.  Maybe you'd find it less daunting if you do what I did when I started building.  Instead of saying "Today I'm going to start building a boat", which was too terrifying, I said "Today I'm going to mark up and cut out a bulkhead.  So start with designing a rig. It's just time, effort and paper.  Then do the intellectual exercise of choosing materials and sourcing them.  By this time, you'll be feeling far more comfortable with the concept and the idea of handing it all over to someone else to complete for you, will be unacceptable!

    I used to have some wonderful friends, sadly long dead, who owned an Elizabethan 31, Greylag, and have very fond memories of the boat.  I went sailing over to the Isle of Man, once or twice with them and remember Alan waking me in the morning with a mug of fresh, steaming coffee, well-laced with rum!  They loved their boat and I'm sure you'll find yours a joy, too.

  • 14 Dec 2016 18:27
    Reply # 4459421 on 4458199

    James, in saying that you're not ready to DIY it yet, do you mean that you want to hand over the whole design and build process to a professional? If so, there's really only been one in the UK - Sunbird Marine, with Robin Blain making up rigs to designs by Alan Boswell. But that route is going to cost a great deal of cash.

    I believe that now that we have this forum, it's entirely possible to start from zero; to read Practical Junk Rig intelligently; then come here to ask questions about things you don't understand; even to get the basic outline of a rig designed for you on an amateur, no-liability basis by several of us who have experience of doing just that. As you'll have seen, we're currently advising James Hleba on a rig for his boat, which happens to be quite similar in type and size to yours. If you're practical, it's not such a hard job to put together a junk rig. Of course, the job can be speeded up by getting some items professionally made. Exe Sails and Covers (back page of the magazine) will make you a sail, if you don't want to learn that skill. The Auminium Lighting Company are now getting used to junkies asking them for bare tapered aluminium poles that are most of the way towards getting a good mast. We have sources for everything you'll need. We're able to provide advice from skilled amateurs on installing rigs.

    To get us started, we need more info on the Elizabethan 31. Sailboatdata.com doesn't give an underwater profile, which is needed to establish the CLR - do you have a drawing?

  • 13 Dec 2016 21:41
    Message # 4458199
    Deleted user

    Apologies first of all as I am sure I have missed the obvious somewhere on the site, but I am considering my first conversion to junk rig and I'm not sure where to start and with whom. I'm practical but not ready to DIY it yet, so should I be looking at a designer first to come up with a plan of what work would need to be carried out to create the new rig and if it was even possible on my boat (Elizabethan 31 centre cockpit ketch). Just a nod in the right direction would be most appreciated.

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