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Junk sloop rig for Benford dory

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  • 24 Oct 2026 10:01
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    Reply # 13758953 on 13756142
    Anonymous member

    Rudder:
    May I ask; is your rudder made with a proper foil section, or is it just a flat one?

    It's a foil section, Arne, with balance, although sitting here, I can't remember how much. I certainly tried to build the rudder according to the guidelines here at the time.
  • 23 Oct 2026 09:23
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    Reply # 13757934 on 13743697
    Anonymous member

    Thank you Arne and Graham. Lots of food for thought! Arne, your design drawings are very much appreciated!
  • 22 Oct 2026 07:20
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    Reply # 13756668 on 13756142
    Anonymous member
    Arne wrote:

    Tony,
    now I have drawn another sloop JR. This time I have placed the fore-aft position of its CE where is sits on the original schooner rig, with two reefs in the mainsail. This sail, with 23% mast balance brings the CE inside the max beam of your dory when running before. I have also sketched in a very moderately canted sail which will make downwind steering even easier (.. it appears that Asmat Downey has opened a door in my head...).  Look up the thread ‘Mast Position’ where Asmat explains how canting the sail is being done.


    (full size diagram under Arne's sketches, section 9-28)

    Hi Arne, this discussion is very interesting, especially Tony's comments about needing to reef the mainsail of his schooner rig early to improve balance.  I remember you and I discussing this in relation to a proposed schooner rig for ARION II.  My major reason for wanting a schooner rig was to maximise sail area, giving 48 sq m, the same as the lofty ketch rig currently on the boat.  But I concur with Tony that a single sail could get away with less, thus around 40 sq m should still drive the ARION II well.  If I can ever find a way to convert ARION II, I think I will go for a single mast and sail of 40 sq m.  Alas, finances, and the pathetic choices for alloy tube in Australia, indicate I would have to build the mast from timber, unless I eventually get my hands on little ARION's unstayed mast.  That boat is just rusting away in an inaccessible backwater at the moment.  I am just living aboard ARION II and trying to build up my funds!  In the meantime, I watch these stories with much interest.
  • 21 Oct 2026 21:05
    Quote
    Reply # 13756142 on 13743697
    Anonymous member (Administrator)

    Tony,
    now I have drawn another sloop JR. This time I have placed the fore-aft position of its CE where is sits on the original schooner rig, with two reefs in the mainsail. This sail, with 23% mast balance brings the CE inside the max beam of your dory when running before. I have also sketched in a very moderately canted sail which will make downwind steering even easier (.. it appears that Asmat Downey has opened a door in my head...).  Look up the thread ‘Mast Position’ where Asmat explains how canting the sail is being done.

    Rudder:
    May I ask; is your rudder made with a proper foil section, or is it just a flat one?

    Btw, that sail is an enlarged version of the sails which are driving Boudicca and Ilvy today.
    ( https://bit.ly/3GSvilq   )

    Arne

    PS: In case the new sail gives lee helm (which I doubt), I have drawn the mast tall enough to let you shift the sail quite far aft.

    (full size diagram under Arne's sketches, section 9-28)
  • 19 Oct 2026 08:21
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    Reply # 13752102 on 13751507
    Anonymous member
    Anonymous wrote:
     So all I can say for sure is that for practical reasons, such as not messing up the accommodation, and structural reasons, I'd build a tabernacle onto the after face of bulkhead 3, 

    Absolutely, David. 

    My sailing experience with this vessel suggests that the CE (as empirically experienced) needs to move a bit forwards. But, as I suggested earlier, that might be achieved with a better sheeting system on the foresail (less, or more controllable, twist). If that is to be the case, then the theoretical CE can, clearly, remain where it is and I'd be nearing it in real life.

    Perhaps I should add that I'm really quite happy with the boat! The idea of a tabernacled mast just intrigues...
  • 18 Oct 2026 22:23
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    Reply # 13751507 on 13743697
    Anonymous member
    David, do you have an idea about where to put the CE of that sloop JR?
    No, I don't. Only long term sailing experience with such a dory would give me or you that, and we just don't have it. So all I can say for sure is that for practical reasons, such as not messing up the accommodation, and structural reasons, I'd build a tabernacle onto the after face of bulkhead 3, and then work up a suitable rig for that mast position.
  • 18 Oct 2026 20:58
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    Reply # 13751428 on 13743697
    Anonymous member

    Thank you David and Arne!

    Yes, Arne, the bulkhead at the forward end of the saloon is the number 3 station. 

    Tapatya weighs in at about 5.5 tons in her current cruising trim.
  • 17 Oct 2026 21:56
    Quote
    Reply # 13750136 on 13743697
    Anonymous member (Administrator)

    Tony,

    before I have a go at drawing another sloop sail, I have found how far the CE moves if the original mainsail is reefed two panels (36.7cm forward). My idea is to draw a sail that moves the CE 40-50cm forward, but with room for shifting it aft again 20cm without ending up with too wide halyard angle.
    That original sailplan is quite blurry. Do you with Station 3 mean the one at the end of the cabin? My first sloop mast has its centre about 23-25cm forward of that.To me it looks as if Mr. Benford has missed a bit this time, probably with too little lead.

    As for David’s idea of making a tall and narrow sail  -  I am a bit sceptical (but I may well be wrong). This dory is rather trim, with a beam of only 10’. Her displacement in cruising trim is said to be 4.3metric tons and the ballast ratio is only 30%.

    Arne

    PS:
    David, do you have an idea about where to put the CE of that sloop JR?

    (full size diagram under Arne's sketches, section 9-26)
    Last modified: 18 Oct 2026 09:02 | Anonymous member (Administrator)
  • 17 Oct 2026 17:50
    Quote
    Reply # 13749832 on 13743697
    Anonymous member

    Tony: a tabernacle is a good way to achieve a higher LAP, and a potent way to get the mast aft of that forward bulkhead is to go for the highest practicable AR, for which you'd naturally need a high LAP. I found no downsides to doing this, even with the shoal draft of Tystie, and of course it improved the off-wind helm balance, too, as you'd expect. And high AR and high sail balance aren't mutually exclusive - both together would bring the mast even further aft. This is the way I'd go - if my armchair was in need of a seagoing rig.
  • 17 Oct 2026 08:27
    Quote
    Reply # 13749213 on 13744513
    Anonymous member
    Anonymous wrote:

    To move the CE as far aft as the CE of the schooner rig sits, I need to give the sloop rig only 15% mast balance. It is not extreme, but not ideal either.
    On a rig over 40sqm, I would rather have 21-26% balance to reduce sheet force and steering imbalance downwind.

    Arne



    Arne: Would I be right in thinking that sail balance would be improved to the 21 - 26% that you recommend by moving the mast back aft of station 3?
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