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Converting a 40ft Offshore

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  • 28 Oct 2025 00:06
    Reply # 13556789 on 13545697
    Anonymous member (Administrator)

    Beautifully proportioned David, it looks nice. But the mast placement does have implications - loss of forward hatch and loss of shower compartment and compromise of twin forward berth (though the mizzen mast does just sneak in aft of the drive train).

    Now I am wondering, how about keep the proportions and the positions of the sails, but replace them with Johanna style, with, say 21-25% balance. This would leave the sail plan balance intact, but allow both masts to move forward a little.

    The mizzen mast would go through the rear of the cockpit and either be offset, or sit on a floor which spans the stern tube. The mainmast would still compromise the twin forward berth. Depending on requirements, masts can be offset from the centreline.

    Here's a VERY rough plonk. Sail area not calculated, but slight increase I suspect.



    In either case the mizzen will need to be high enouigh to clear standing head height, or it will be an annoyance to the person on the helm.

    They all need fine tuning, but suddenly choices abound.

    I suppose sail area could be increased a little, without upsetting balance, by increasing aspect ratio of both sails. I'm not sure if there is any need, though.

    Mark might note that the Johanna planform gives a bit of wriggle-room in the final positioning of the sails, and it would be quicker to make the sails than with the Poppy.


    The hybrid schooner still has the merit of being possibly the quickest to implement and least disturbance of deck and internal arrangements, but there isn't much in it. 

    The ketchs have better weight distribution.

    If Mark is planning to live on board full time (not sure how many people) then internal accommodation arrangements might have to be the deciding factor. 

    I guess Mark will be applyhing for a visa extension in any case...

    Last modified: 28 Oct 2025 00:45 | Anonymous member (Administrator)
  • 27 Oct 2025 14:54
    Reply # 13556549 on 13545697

    Well, since I've advocated a ketch rig, I thought I'd better make a doodle of what it might look like, to check whether it will work.

    ... so I took Poppy's SJR sail which, at 50 sqm/537.5 sqft with batten length 5.95m/19.5ft, is exactly the right size for the mainsail, and superimposed it on Graeme's drawing.Then I scaled that sail down to 19.8 sqm/212.5 sq ft and took out one batten to make the lower panels a bit larger, for the mizzen. I think it has to be a SJR again, to put the mizzen mast in a sensible place. Total area 750 sq ft, with CE on the green line.

    The main mast is about 44ft long and goes through the forehatch aperture, and the mizzen mast is about 30ft long and goes just forward of the current mainsheet track (as far as I can tell, without seeing detailed drawings of the hull and deck). The main would be sheeted to a point just forward of the binnacle. The mizzen would be sheeted to very much strengthened davits.

    I think that (if I were 20 years younger and fit and strong enough to undertake such a task) I'd need at least six months to design and build such a rig, and then get it shaken down enough for an ocean passage. At least.


    2 files
    Last modified: 27 Oct 2025 15:02 | Anonymous member
  • 27 Oct 2025 05:28
    Reply # 13556435 on 13545697
    Anonymous member (Administrator)

    Hi Mark

    There are some difficulties, but I don’t think you need to feel that you have offended anyone.

    To be fair to yourself, your request was fair enough: “I have the boat, masts and sail material, but lack the confidence to continue with the project without the input of more knowledgeable and experienced  people… running out of time… please advise me or give me contact details of anyone that can help”. 

    The ones who have real expertise can speak for themselves.  Slieve has done so, fairly bluntly, and if I could summarise his main points (with which I sympathise) he is concerned that you don’t have enough time to embark on the necessary learning curve and complete the design and installation of a fairly large rig, and he is not in a position to design it for you. I suspect that speaks also for the others who, for various, quite valid reasons, are also not at the moment in a position to do it for you, and don’t want to be dragged into encouraging you to “bite off more than you can chew”.

    David, who probably has the widest experience of sail design combined with ocean sailing, and would probably have been your best advisor, has actually posted four times and given you some very good, practical and wise, general advice, including a possible contact, (though, good luck in trying to make contact with Alan Boswell as I have tried a number of times over the last year and never had a response. I think we are all getting too old, Mark!)


    The difficulty for me is fear of stepping outside my level of competence. I can advise you on some basic mathematical things, but my direct experience of junk rig conversion is limited to a couple of relatively small boats, the rest being merely accumulation of a fair amount of information from other people’s experience.

    On the other hand, I do have a pretty good understanding of what it feels like to be on the threshold of commencing a project, out of depth in certain critical respects, and struggling to reconcile the various, sometimes conflicting preferences of people who have successfully done it. I have had a lifetime of experience at being in exactly that situation, and no lack of sympathetic understanding.

    My advice is don’t give up. If you must have a schooner rig, you are now close to one which ought to function. I agree with David that it is somewhat lacking in aesthetic qualities, though that is very much in "the eye of the beholder", and it might not give you the quite the convenience or performance that a ketch rig would, but on the other hand it has the distinct advantage of matching the existing internal and deck arrangements, with a minimum of re-arrangement and therefore probably the quickest path to completion.

    Your reasoning for having a SJR forward (high balance for best mast position) and a Johanna-style rig aft (low balance for maximum sheeting clearance between the sails) is rational, given the chosen mast positions.  

    You have already built a junk sail for a 32’ boat and sailed 9,000 miles with it. You have crossed the Atlantic. So, you will know what your requirements are. If a schooner rig is “your cup of tea” and if the proposed mast placement positions are what suit you best - you have the masts and sail cloth – you have a sketch plan which will balance near enough (with the flexibility that a two-masted rig provides) – so, “go for it”.

    Perfection is the enemy of progress.


    Last modified: 27 Oct 2025 12:09 | Anonymous member (Administrator)
  • 26 Oct 2025 16:24
    Reply # 13556300 on 13545697

    Hello all. 

    I most humbly apologize to anyone I have offered. 

    My only excuse is, lack of knowledge and the urgency in starting this project because of my time limit. 

    I have been researching this project for a long time,  reading the forum , and the public domains of both Arne and Slieve. Admittedly some ,no nay ,most of it being above my pay grade. 

    Naturally planning can only begin when you have the boat. 

    I am very thankful to everyone that has contributed and grateful for their time 



  • 25 Oct 2025 17:43
    Reply # 13556081 on 13545697

    Hi Mark,

    I read with dismay your latest emails which you have sent off website, and the responses on the website.

    It is almost a month since you first wrote to me about this project and despite the help and information you have received you still do not have a sail plan. From the beginning I explained that I have moved on to other things and also pointed out that I am not prepared to advise on things that I do not have personal experience to quote from.

    On the 10th October I wrote, “So my personal reaction is, Ouch!” but yet you persisted to ask me to to do simple calculations which you should have been completing in a few minutes. In that same letter I also wrote, “The trouble is that I don't see an easy setup which keeps the cockpit clear, except by trying to draw up a ketch with the mizzen just behind the helmsman. That might be made to work.” Again I have not experience of drawing such a set up. It’s interesting that David and Graeme seem to be having similar thoughts.

    I believe your web posting on the 20th is the first time anyone has complained about lack of help from the junk rig community. I do not think it reasonable to expect members to hand you a completed design on a plate. Help is one thing, but providing a design service is not the name of the game.

    On the 8th October I wrote off line, “Possibly the thing that worries me most is that you have so little time before your visa runs out. I know it took me a lot longer than planned to install the first SJR, so I don't believe you will be ready to sail away with a schooner rig in your available time. Even preparation for a long trip without modifying the rig will put some pressure on yourself. I believe the job is bigger than the time available, and I don't want to encourage you to bight off more than can be chewed.” If after 3 week you still do not have a sail plan then I suggest re-read my comment above. The only advice I can give you is to be realistic about what you are trying to achieve.

    Slieve.


  • 24 Oct 2025 16:03
    Reply # 13555713 on 13545697

    With the two sails of either a ketch or a schooner, the after sail has to be trimmed in more than the fore sail, so when sailing to windward, it is contributing more to heeling, less to forward drive, than if it were a single sail, or the fore sail of two. Thus it makes sense to me that the fore sail should be the larger of the two, doing nearly all the driving, and the after sail is there to add a little more drive, and to ensure that there's no lee helm, in light going. This is not just theory, it's what I experienced over many ocean miles in my 34ft Tystie. Like Graeme, I'm more and more convinced that this boat is asking for a ketch rig.

    Purely from an aesthetic point of view, I'd want the sails to look as nearly alike in planform as possible even if one is a SJR - and a SJR for the foresail makes sense whether you go for ketch or schooner, as it puts the foremast further aft, which is good for structural reasons, performance and ease of working on the foredeck. 

    Last modified: 24 Oct 2025 16:05 | Anonymous member
  • 24 Oct 2025 14:55
    Reply # 13555674 on 13545697

    Wow Graeme. Thank you. Your drawing is much better than mine. 

    This is exactly what I had in mind and will be the easiest to build. 

    I don't understand your reluctance and why the ketch with a bigger 

    Main ?

    What would be the advantage  ?

    Thanks again for your help. 

  • 24 Oct 2025 06:04
    Reply # 13555587 on 13545697
    Anonymous member (Administrator)

     

    Here's how my trial drawing turned out, just for comparison.

    Pretty close. Your CE is an inch or so further forward than you have drawn it, I suspect.

    My rough drawings were only for the purpose of showing you what to do.

    I have used a scale copy of the Amiina ll rig for the foresail. You might want to discuss with Slieve the pssibility of increasing its aspect ratio.

    You have to make sure now that you have correctly calculated the sail areas (both the original bermudan and the recent junk sails), and that you have correctly calculated the CE of both the bermudan and junk sail plans, and that the two CEs coincide on the same vertical line.

    Unless you are confident of your drafting and your calculations, it might be an idea to do a more accurate drawing now, using CAD software, from the first step of finding the original bermudan CE.  The CAD software will do the sail area calculations for you.



    I am inclined to agree with David, a ketch rig might suit the vessel better. With a ketch you could have had a bigger mainsail, possibly commensurate with the 550/300 split you had originally envisaged. However that depends on internal arrangements, and your own taste, I guess. Good luck.



    Last modified: 27 Oct 2025 10:28 | Anonymous member (Administrator)
  • 24 Oct 2025 02:35
    Reply # 13555555 on 13545697

    Eventually managed to finish the drawing, and the 

    CE of the original sails and the new setup, using your 

    suggestions on sail sizes, seems very close. 

    Thank you 

    1 file
  • 21 Oct 2025 02:27
    Reply # 13554330 on 13545697

    Thank you Graeme and David. 

    I will redo the drawing and  try be more accurate. 

    I will ask Slieve about increasing the size of the foresail 

    And also find a smaller Anre main sail. 

    Thanks again. 

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