Irish Trawler seeking a JR

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  • 30 Apr 2017 23:31
    Reply # 4792847 on 4515814
    Anonymous member (Administrator)

    Randy.

    I think the sewing is no more difficult with a fanned sail than one with parallel battens(and several identical panels). However, if it is your first sailmaking project, you will find it much easier and quicker to loft each panels if you go for the simpler McLeod style sail.

    As for camber or not, I think that such a heavy vessel would need quite a bit of it  -  that is, unless you plan is mainly to drift (or motor) about, looking picturesque...

    Arne

    Last modified: 01 May 2017 17:16 | Anonymous member (Administrator)
  • 30 Apr 2017 22:55
    Reply # 4792788 on 4515814
    Deleted user

    Hi Arne, thank you for your thoughts. 

    Interesting your point on the parallel sections of sail. I am very attracted to the non parallel fanning style visually. How much of a difference will this make? I do have the gear, a walking foot sewing machine, to make the sails. It's all about budget. If I've enough to have them made I will, but I'm happy to take on the sharp curve of learning the art of making my own sails. 


    I'm not sure about the other point and thank you for it as a consideration to help me get this right first shot. I have seen this barrel shaped style sail  what would you recommend?

    R

    Last modified: 30 Apr 2017 22:56 | Deleted user
  • 30 Apr 2017 22:26
    Reply # 4792777 on 4515814
    Anonymous member (Administrator)

    Hi Randy.

    To me the design made by Alan Boswell looks by far to be the most realistic. I appears to have enough space for the sheets and tall enough masts to get the halyards and slingpoints right on the yards.

    However, there are two points I wonder about:

    1.      Are the sails meant to be flat? The reefing diagram at the lower end of the drawing will only be valid if they are flat.

    2.      Are the sails meant to be made by a sail maker, or are they meant to be a DIY project? In the latter case, I would suggest slight changes to each sail to give four or five identical parallelogram panels plus three fanning panels in the top. This has the added advantage of making the leech vertical.

    Arne


  • 30 Apr 2017 14:42
    Reply # 4792385 on 4515814
    Anonymous

    Yep. Working now.

    Chris

  • 30 Apr 2017 13:39
    Reply # 4792348 on 4515814
    Deleted user

    Try now Chris. Cheers. 

  • 30 Apr 2017 10:26
    Reply # 4792249 on 4515814
    Anonymous

    Hi Randy

    I just get 'iCloud can't find that page' from that link.

    Alan Boswell is one of the founders of, and ex-chairman of the JRA and has designed hundreds of junk rigs.

    Chris


  • 30 Apr 2017 09:53
    Reply # 4792239 on 4515814
    Deleted user

    After a my initial exploration into junk rigging here and reading practical junk rig I found a junk rig designer in the JRA mag, Alan Boswell. Here in my part of the world. I've recently revived the design which we toiled over for the last couple months. 


    Here is the design, I'd love some thoughts and feedback. 

    JR design

    Last modified: 30 Apr 2017 13:38 | Deleted user
  • 09 Jan 2017 17:07
    Reply # 4518040 on 4515814
    Anonymous

    There's also Blondie's 3-masted design for Sea Bear, although I think I'd want to rake the foremast forward around 8 degrees, and make the foresail near identical to the mizzen, giving around 1200 sq. ft.

    Chris

  • 09 Jan 2017 16:35
    Reply # 4517971 on 4515814

    Rad, have you got a copy of Practical Junk Rig yet? You're going to need it as a reference for all the rigging, but in the immediate future, it will talk you through the process of designing the sailplan, in detail, and getting the balance right. It's available from Amazon, and also on eBay for £34.

    And Chapter 16 describes various examples of junk rigged boats. In particular, there's "Design SSF/1" (designed by Blondie Hasler, but not actually built). It's based on a Scottish Fifie, which is a plumb-ended 50ft fishing boat not dissimilar to yours.

    The rig is a junk ketch, with the mainmast well forward, carrying 1020 sq ft, and the mizzen mast just about where your deckhouse is, carrying 510 sq ft. The mainmast was planned to be lowered.

    This placing of the mizzen may not be convenient, but at least it confirms the total sail area needed as being in the region of 1500 sq ft. 

    A crab winch was intended to be used for the main halyard, and I would certainly want a reel winch with a brake to handle such a large, heavy sail.

    Last modified: 09 Jan 2017 17:22 | Anonymous member
  • 09 Jan 2017 13:36
    Reply # 4517500 on 4515814
    Deleted user

    Hi Randy,

    There are a few different types of "balance" that seem to come up, so it helps to keep them straight. 

    1) The weight balance you mention is about hull trim: moving weight around so she stays on her designed waterline. 

    2) Then there's the "balance" of the amount of sail forward vs aft of the mast.  Split rigs have upwards of 30% forward of the mast.  Bermudians have 0%.

    3) Rudder balance is like number 2 above, but about the rudder around the rudder post, , not the sail around the mast.  Some people are strong proponents (like our very capable Arne) of a substantial and balanced rudder for Junk conversions.

    4) But at the moment, we're talking about sailplan balance. This is about the location of combined lateral force on the sail in relation to the combined laterals force on the hull.  Imagine no sail aft of the midship line, and lots right up near the bow.  This would cause the boat to pivot on the keel off the wind.  All sail near the stern and none near the bow would cause it to weathercock into the wind.  "Balanced" in this sense would be no tendency to do either because the sail is balanced with the hull.  (Things get complicated as far has how much unbalance you want.  Perfect balance is actually undersirable because there's little feedback to the helm.)  This gets dynamic because on different points of sail, you have different forces at work, both under and above water.  David's got a really good point:  the sister ship has put a lot of sail forward, with a long bowsprit. That indicates that the hull form you've got might need sails way up there to avoid lee helm.  Is there any way you can talk to the owner of that sister ship and get a sense of how she likes her sails set in various conditions and points of sail?

    Last modified: 09 Jan 2017 13:39 | Deleted user
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