Split Junk Rig on Westerly Windrush

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  • 24 May 2013 01:30
    Reply # 1300295 on 1248976
    Deleted user
    I am following this conversation with a lot of interest. I bought a Shark 24 early April and I have been working on it since then. I will rig it with the original Bermudian rig for this season to get a feel of the boat and also to be able to sail at all. It's a 42 years old boat and there are quite a few jobs to attend to before launching it. In the meantime I have also cut a straight spruce to a length of 29' from a tree I had felled in the fall. I debarked the trunk and roughed out the shape with a power plane before cutting a slot through its length. It is now drying resting on brackets in the shade. The future mast will have plenty of time to dry as I am planning to go cruising next year for a year so that the conversion won't happen much before 2015. Hopefully by then Slieve you might have finished your write-up about the split rig. As my first destination is Scotland in June 2014 I am hoping to see a few junk rigged boats and discuss with their owners on my way south during the summer. Cheers Thierry
  • 23 May 2013 22:00
    Reply # 1300180 on 1248976
    Deleted user
    Thank you both for your useful replies. I will take your advice on area, Sleive. I was originally thinking along the lines of a rule of thumb I've seen somewhere which is to take standard area and add 10%. Having thought around this problem for a while it is clear to me that my boat would be considerably over-canvassed with that much area. I guess that 'rule' might apply to sails with little or no camber. I will stick to the main + 135J for the Windrush, which is 312 sq ft  (even that seems generous for a boat this size).
    Last modified: 23 May 2013 22:00 | Deleted user
  • 23 May 2013 21:46
    Reply # 1300166 on 1248976

    Gerry, thanks for the write up on your trip with Edward. He’s got a nice boat, and it is ‘FUNto sail.

    Chris, The answer to the height of the C of E is that all rigs are a compromise, and you will never get all the little ducks in a perfectly straight line, or the line you really want. When I look at the drawings of Poppy I do see that the C of E is higher than the Bermudan rig, but when I sail the boat I do feel the performance is better than the Bermudan rig, so I’m happy with it.

    There are two considerations. I know that Arne likes to pile on the sail area, and I’m pretty sure I would do the same if I sailed around his wonderful sailing ground. On the south coast of England I am happy with the area of my rig for two reasons.

    I wanted to compare with the ‘standard’ Bermudan cruising rig of 100% mainsail and 135J or No 2 roller reefing Genoa, so I used that as my sail area. In practice this has worked well with the winds and tides we get here. In practice, with the efficiency I seem to be getting with the rig I haven’t found myself short of area, even in very light winds.

    The other consideration about the height of the C of E is quite interesting. Aware of this situation I was comfortable to have less than full main plus full No 1 Genoa area. After sailing Poppy I was more than happy as the raised C of E did not present a problem. This could be because the drag angle seems to be low and the thrust from the rig is more forward and with less of a heeling component than the Bermudan rig, which seems to balance the higher C of E position. If sheeted properly this slightly reduced area was still able to produce the required drive for lively sailing.

    With this background the question of sail area for Edward’s ‘Amiina’ was a dilemma. This was a fractional rig with a large mainsail, so it seemed reasonable to go for full area. Also Edward was planning to sail ‘Amiina’ in the Round the Island Race, so we went for the same area as the standard boat to get the ‘standard’ handicap. It was only when we came to get a handicap that we discovered that there are two standards for rig size, the one provided by the designer in the original specification, and a smaller one which is generally used as it gives good performance and gets a better racing handicap. It seems to be that the smaller ‘standard’ rig is right for the boat, and that it is a little tender for the designer’s rig. A real dilemma.

    I think that for the Windrush a split junk with an area of 100% main plus 135J Genoa would probably be fine. ‘Poppy’ is a Longbow, which is largely a scaled up Windrush with a fin keel.

    Cheers, Slieve.

    Last modified: 24 May 2013 10:17 | Anonymous member
  • 23 May 2013 12:55
    Reply # 1299682 on 1248976
    Deleted user
    Raising CE will undoubtedly make a boat more tender. Mostly a junk is sailed freer than a pointy top, not so heavily sheeted in, and this mitigates the roll. The very rapid reefing means that you can always sail a junk to the wind you've got now so avoid being overpowered (or underpowered). But if, after all this, she's still uncomfortably tender then there's the option to add more ballast.

    Edward Hooper was kind enough to take me for a sail on Tuesday in Amiina, a light and weatherly little boat with dinghy-like sailing characteristics. He is experimenting with additional ballast in her and that seems to be working well. While Edward has concerns about his acceleration, carrying an extra 140kg of weight, for my taste I wouldn't want that boat to be more tender than she is. But then I sail a six ton old lady that I like to keep as upright as possible as I sit back and enjoy the scenery going by. I am not a racing sailor.

    Our sail was a club outing, a run downwind from Poole to Swanage where we arrived half a mile in front of the rest of the fleet in spite of a) being the smallest boat in it and b) dropping a couple of panels over the last mile to slow down for the ETA competition, followed after lunch at Durston castle by a beat back. The wind was force 2-3 on the beat and while we did get pushed over a bit in a gust the roll angle was perfectly comfortable for the great majority of the time.

    The performance of the split rig was impressive. I took the helm as we entered the harbour and ended up short tacking up the North Channel in a fading force 2 against the tide. The sail kept its shape beautifully in the light wind and Amiina sailed thirty five to forty degrees to the relative wind, making light work of conditions where Ivory Gull would certainly have had to motor. Acceleration out of the tacks was not a problem, even though Amiina does not carry her way as well as other boats I've sailed.
    Last modified: 23 May 2013 13:18 | Deleted user
  • 23 May 2013 09:41
    Reply # 1299612 on 1248976
    Deleted user
    Hello all, still thinking about this conversion and trying to devise a suitable sail plan. It has become obvious that most junk rigs present proportionally more sail higher up than their 'pointy' brethren, and therefore any conversion will involve raising the static centre of effort considerably.

    In my case, typical planforms raise the CE around 4 feet, which combined with a fairly narrow hull and rather light ballast ratio might make her rather too tender.

    I would be grateful to hear the experience of the membership in this regard.
  • 01 Apr 2013 16:11
    Reply # 1256198 on 1248976
    Deleted user

    Thank you very much for that - I knew there was a Windrush junk conversion somewhere -  it is indicated in JRA listing - but was unable to find any trace of it online. Your comments are very encouraging, and it sounds as though exactly the improvements I hope for were achieved with that conversion.

  • 01 Apr 2013 13:11
    Reply # 1256075 on 1248976
    Chris Gallienne wrote:Hi, all. Hoping Slieve will comment on this but all others' comments also welcome.

    I have a 40-year old Westerly Windrush 25' 1" LOA. Nice old boat, very solidly built, but ponderously slow, and won't point, and reluctant to tack. This is partly due to her triple keel arrangement, which is otherwise very convenient. But I am unhappy with the rig. Apart from being in dire need of upgrade, the horrible main boom roller reefing means that with any reef the main loses all shape and she points and goes even less well. Also has quite a lot of weather helm under full sail, surprising when you look at the lead of the CE on CLR (which is well aft, again due to keel arrangement).

    Thinking of converting to Split Junk, and have been happily devouring all the info I can get hold of on the subject. What I propose is as follows:

    New 8.5" hollow wood unstayed mast positioned well forward. Split Junk main of 352 sq ft (old rig around 312 sq ft). 30% balance (any more would move the mast too far aft or the CE too far forward). 1.68 Aspect Ratio to keep the mast LAP below 28ft. This would improve SA/disp from about 18 to 21.

    To my mind this conversion would seem well-suited to this boat, but would welcome the observations of the more experienced with this rig.

    I'm coming rather late to this thread, but just thought it would be worth saying that there is already  a Westerly Windrush 26 converted to junk rig. It was my father's boat, named 'Westerlies', it performed much as you describe with its bermudan rig, and sailed hugely better with junk rig. The boat is still around; it was sold several years ago and I understand has voyaged extensively since with its next owners, who put it up for sale again quite recently. The junk conversion was all carried out by Robin Blain of Sunbird Marine, the mast was a tapered Needlespar aluminium production and the rig form was the conventional Sunbird rig of the 1990s, drawn up by Alan Boswell specifically for this hull. I am sure that Robin will have all the details on file, including the mast positioning, which worked very well - the forward V-berth was still entirely useable. I'm fairly sure that we also retained the forehatch, but not certain. It was certainly a success, enabling my father, Jack, to sail for many more years despite advancing age and lack of crew - the bermudan rig was a pain, being either underpowered in light winds or overpowered in strong and requiring awkward deck work since the full-width coachroof design meant that access to the sharp end was precarious and unsafe for ageing limbs. With the junk rig the performance was transformed; where the old rig produced quite unnerving angles of heel whenever there was enough wind to produce adequate progress, the junk rig had the ability to produce useful drive with little heel and less leeway. The performance envelope was much broader, with the rig working well in lighter winds and yet far easier to manage in stronger winds. The tendency to round up alarmingly in strong gusts was almost abolished (since the hull was more upright and the keels and rudder still immersed at a useful angle) and reefing was a cinch. The sail area used was that of main + full genoa, taking full advantage of easy reefing to give generous area for light weather. An altogether successful conversion, I hope yours will be equally beneficial!
    Gavin Dalglish
  • 31 Mar 2013 23:41
    Reply # 1255717 on 1248976

    Hi Chris

    I’ve been reluctant to publish the Splinter rig until I’ve seen it sail and am happy with it, but I’ve sent you a copy off web. The design is ‘brutal’ as I have made no consideration for aesthetics, believing that function is all important, and if it works well and is efficient it will be accepted as pretty (enough).  If a rig is inefficient then it doesn’t matter what it looks like, as it has no place on a sailing boat, in my opinion.


    As the chord of the jibs on successive split rigs has increased I have found it more difficult to draw the camber and sheeting angle of the jibs such that the camber does not choke the airflow and increase the drag. At this stage I have been using a height/ chord limit of not less than 0.88 (or was it 0.81)*, but this means the panel height has increased as the balance has increased. With this in mind on Amiina we settled on there being only 6 panels, but this was considered to be adequate from a reefing point of view.


    Edward’s rig was drawn to be as easy (cheap) as possible for the sailmaker to build, with the minimum of lofting. It includes a number of experiments which will be reported when I see how they work out.


    I hope this helps,

    Cheers,  Slieve


    * I'm not sure of this figure at the moment and will have to check it.

    Last modified: 23 May 2013 16:33 | Anonymous member
  • 31 Mar 2013 19:18
    Reply # 1255629 on 1255388
    Deleted user
    Slieve McGalliard wrote:Do you have a copy of Edward’s rig, and if not I’ll send you one? I know I call it a ‘brutal’ design, but it is as simple to make as possible with minimum lofting.

    No, I have seen the photos Edward has posted, but cannot see a sail plan anywhere - would be very useful to have a copy if you don't mind sending it.

    Why do you call it a 'brutal' design?

    Last modified: 31 Mar 2013 19:18 | Deleted user
  • 31 Mar 2013 10:43
    Reply # 1255391 on 1248976
    Deleted user

    Yes I am still experimenting and am more concerned at this stage with general sail shape, area and position, and whetehr it can be fitted on my boat. I would not consider those sketches to be sail plans and would hope no-one else will.

    I don't really know how much reefing I need - but the boat is not one that I would want to be out in in more than F6 and not that much if I was starting a sail. It would be wise to plan for that much though I guess.

    Do you have a general guideline you would use for chord to panel height ratio?

    Last modified: 31 Mar 2013 11:02 | Deleted user
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