S2 6.7 Junk Rig Conversion

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  • 27 Oct 2020 07:18
    Reply # 9327905 on 6872873
    Anonymous member (Administrator)

    Scott,
    Maybe it's an idea to have a look at the dimensions of my Frøken Sørensen.  The dimensions of those boats are very similar.
    Check this: 

    https://bit.ly/3jBkOdY

    Arne



  • 27 Oct 2020 05:40
    Reply # 9327852 on 9326325
    Scott wrote:

    I like this video. Watching the materials bend under load and how they fail was very educational for me. It seems that correct type of fiberglass or standard modulus carbon fiber tubes would be the best option. They are stiff but also flex and return to their original shape after extreme loads. Watching the aluminum tube buckle and fail was not very reassuring.


    I think the thing that makes aluminium tube fail is point loading. I had this with the yard on 'Footprints' where the alloy tube eventually failed at the mid point, or halyard attachment point. With battens there is, it seems to me at least, to be a more even load over the whole length of the batten, and yes they may flex a bit under strong wind conditions, but should retain their shape. It seems to me that various folk have had failure with T6 alloy, but those T5 battens on Footprints have now done thousands of miles and stood up very well. I know because I was out sailing on her just a couple of days ago, and that very large camber panel sail puts a lot of load on the battens. On the original sail I replaced very bendy plastic tube battens with battens constructed of Western Red Cedar which is not the ideal timber choice. I reinforced the timber with either one or two layers of uni-directional fiberglass which seemed to add the required strength and rigidity, as needed by the traditional HM flat junk sail.  

    Certainly carbon fiber battens would produce the ideal combination of light weight and rigidity, but you need very deep money pockets to purchase those

  • 26 Oct 2020 15:09
    Reply # 9326325 on 9324785
    Annie wrote:

    Yes, that is exactly what happened with my fibreglass battens.  Equally irritatingy, I said to the suppliers that I wanted an equivalent stiffness to 2 x 1 douglas fir, but they were nothing like as stiff, when the arrived.

    I don't recall the sail area of your new rig.  However, I was relieved to see you had gone for larger battens: I managed to bend a 38mm, T6 batten quite badly and another one slightly.  It rather put me off alloy battens, but most people have no problems with them.

    My sail is 22 sqm. If I did the math right then PJR recommends spruce battens with a 1.125" section. I have given up on using metric for everything. I am using mixed units in my head and for paper calculations.

    I just finished a weekend long sprint of ripping seams, cutting fabric and re-learning how to use my sewing machine. The new battens seems much better. There is some deflection but I think they have more stiffness than 1.125 inches of spruce.

    I like this video. Watching the materials bend under load and how they fail was very educational for me. It seems that correct type of fiberglass or standard modulus carbon fiber tubes would be the best option. They are stiff but also flex and return to their original shape after extreme loads. Watching the aluminum tube buckle and fail was not very reassuring.

    But in the end the only reasonable option for me was to go with what is available locally. I guess there are more people building commercial and industrial stuff out of 6061-T6 than unidirectional fiberglass where I live.

    2 files
  • 25 Oct 2020 18:34
    Reply # 9324785 on 6872873

    Yes, that is exactly what happened with my fibreglass battens.  Equally irritatingy, I said to the suppliers that I wanted an equivalent stiffness to 2 x 1 douglas fir, but they were nothing like as stiff, when the arrived.

    I don't recall the sail area of your new rig.  However, I was relieved to see you had gone for larger battens: I managed to bend a 38mm, T6 batten quite badly and another one slightly.  It rather put me off alloy battens, but most people have no problems with them.

  • 23 Oct 2020 07:08
    Reply # 9321009 on 9319328
    Anonymous wrote:
    Kris wrote:

    Scott,

    I scroll back thru the conversation to the info regarding a lamp post. Does your post has an inspection door in the lower part? What you going to do about, if so? This is my case and I am not certain how to deal with it.

    Hi Kris,

    Your profile says that you are building one of Jerome Delaunay's designs. I like how his boats look as drawings. I hope you will share some build photos. The center cockpit scow with two masts looks especially interesting.

    The short answer is that my lamp post does not have an inspection door.

    The long answer is that I was able to avoid the issue with the inspection door after some persistence. The first two vendors I contacted stopped talking to me as soon as they found out I wanted to use the the lamp pole as a mast.

    I tried to keep quiet about my intentions with a third vendor but eventually he told me that they can't sell a lamp pole without an inspection door. The inspection door is required by the NEC (National Electrical Code). I imagine that there are similar regulations in the EU.

    However this third vendor was very happy to sell me a pole without a hand hole after I told him that I would not be using it for a lighting application. I had to sign several documents but in the end I was able to purchase a plain tapered 6063-T6 pole without any holes.

    I remember seeing photos from at least one JRA member who purchased the pole longer than necessary and then cut off the lower section with the inspection door. If I remember correctly the mast on Ming Ming II was made this way.

    Please understand that I have not yet built a functional junk rig with this pole. The most I have done is get the mast vertical in the tabernacle. I am not any sort of an expert or authority. With that said I think you have a few options.


    1. If the pole is long enough cut off the lower section

    2. Cut off the lower section and extend the upper section with wood or an alloy tube

    2. Get a different pole

    3. Add a sleeve inside the lower section or on the outside of the lower section

    4. Determine, somehow, that the pole is strong enough with inspection door installed normally.

    Thank you Scott for sharing the story. Lucky you and persistent enough. I went exactly thru the same, ending up in a whole-seller warehouse keeping mouth shut. Since I planned to use the tabernacle anyway, I think will make it higher then 10% and burry the part with a door, which is about a 1 meter. 

    Regarding my new "ANNA LUCJA 2" i post frequently on my FB account ( https://www.facebook.com/kris.matuszewski.1 ), but of course along with other stuff.

    Yeah, I must do better with the CARAVELINA topic here in the JRA site 

    https://www.junkrigassociation.org/technical_forum/7917477#7926500

    I  am very interested to watch your progress with the conversion and learn a lots from all the discussions. I am waiting for reports from the sea trials. 

    Good luck

    Kris



  • 22 Oct 2020 21:49
    Reply # 9320366 on 9320170
    David Th wrote:

    Possibly slight overkill with the diameter but you should have pretty bullet-proof battens. You could probably use the same tube as your boom. The tube should also be very light with that wall thickness, which makes a difference when it is time to hoist the sail.

    I would like to go to the warehouse like you did and get a feel for how light or heavy, stiff or bendy each option is in person. I have not found anything around here.

    I ordered a sample pack of the fiberglass tube from MGS before placing the big order. Looking at the 2 foot long samples I thought it would be fine. It was very different when the full size tubes arrived.

    Since I have to replace the batten pockets anyway I am aiming for 'too big' on this second try.

  • 22 Oct 2020 19:53
    Reply # 9320170 on 9319603
    Scott wrote:

    I ordered some more tube with this spec:

    'Aluminum 1-3/4 OD X .065 WALL(1.620 ID) 6061-T6 EXT STRUCTURAL TUBE P1'

    I hope I can make these work and also find a purpose for the floppy fiberglass tube. It is getting difficult to explain why I need all these long pieces hidden around the house and garage.

    Possibly slight overkill with the diameter but you should have pretty bullet-proof battens. You could probably use the same tube as your boom. The tube should also be very light with that wall thickness, which makes a difference when it is time to hoist the sail.
  • 22 Oct 2020 16:37
    Reply # 9319603 on 9317726
    David wrote:
    Er, no, perhaps he isn't, not having used aluminium battens for more years than he cares to remember. A more recent user can probably speak with more authority, but purely as a guess - 1.25" x 0.065" 6061T6, at least for the upper sheeted battens, even if the lower ones can be 1" x 0.065"?

    I ordered some more tube with this spec:

    'Aluminum 1-3/4 OD X .065 WALL(1.620 ID) 6061-T6 EXT STRUCTURAL TUBE P1'

    I hope I can make these work and also find a purpose for the floppy fiberglass tube. It is getting difficult to explain why I need all these long pieces hidden around the house and garage.

  • 22 Oct 2020 14:43
    Reply # 9319328 on 9318798
    Kris wrote:

    Scott,

    I scroll back thru the conversation to the info regarding a lamp post. Does your post has an inspection door in the lower part? What you going to do about, if so? This is my case and I am not certain how to deal with it.

    Hi Kris,

    Your profile says that you are building one of Jerome Delaunay's designs. I like how his boats look as drawings. I hope you will share some build photos. The center cockpit scow with two masts looks especially interesting.

    The short answer is that my lamp post does not have an inspection door.

    The long answer is that I was able to avoid the issue with the inspection door after some persistence. The first two vendors I contacted stopped talking to me as soon as they found out I wanted to use the the lamp pole as a mast.

    I tried to keep quiet about my intentions with a third vendor but eventually he told me that they can't sell a lamp pole without an inspection door. The inspection door is required by the NEC (National Electrical Code). I imagine that there are similar regulations in the EU.

    However this third vendor was very happy to sell me a pole without a hand hole after I told him that I would not be using it for a lighting application. I had to sign several documents but in the end I was able to purchase a plain tapered 6063-T6 pole without any holes.

    I remember seeing photos from at least one JRA member who purchased the pole longer than necessary and then cut off the lower section with the inspection door. If I remember correctly the mast on Ming Ming II was made this way.

    Please understand that I have not yet built a functional junk rig with this pole. The most I have done is get the mast vertical in the tabernacle. I am not any sort of an expert or authority. With that said I think you have a few options.


    1. If the pole is long enough cut off the lower section

    2. Cut off the lower section and extend the upper section with wood or an alloy tube

    2. Get a different pole

    3. Add a sleeve inside the lower section or on the outside of the lower section

    4. Determine, somehow, that the pole is strong enough with inspection door installed normally.

    1 file
    Last modified: 22 Oct 2020 14:56 | Anonymous member
  • 22 Oct 2020 06:45
    Reply # 9318798 on 6872873

    Scott,

    I scroll back thru the conversation to the info regarding a lamp post. Does your post has an inspection door in the lower part? What you going to do about, if so? This is my case and I am not certain how to deal with it.

    1 file
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