S2 6.7 Junk Rig Conversion

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  • 22 Apr 2020 08:19
    Reply # 8920813 on 6872873

    David T: “The tops of these tapered tubes are generally parallel for a short distance, to enable the lamp-post makers to fit the light more easily, so in fact, getting a good fit for a short extension is no problem.

    That is good news and negates some (though perhaps not all) of the reasons for suggesting that a larger diameter heel plug extension might be better or easier to make than a small diameter topmast extension.

    I sure wish we could get these lamp posts in New Zealand.


    Last modified: 22 Apr 2020 08:27 | Anonymous member
  • 22 Apr 2020 07:33
    Reply # 8920791 on 6872873

    I was in the same position with both Tystie and Weaverbird, wanting my aluminium mast to be a bit longer.

    On Tystie, I made a wooden extension, a metre long, and that was a mistake. It failed due to fatigue (but only after sailing the Pacific from top to bottom). It was the combination of too much length, too little diameter and possibly unsuitable timber that did for it.

    On Weaverbird, I got a 9.2 metre tapered pole, and really wanted just a little bit more. I got my brother in law to turn me a short extension from PVC bar, and drilled and tapped it for M8 screws to fasten on stainless steel eyeplates. This has been entirely satisfactory. The tops of these tapered tubes are generally parallel for a short distance, to enable the lamp-post makers to fit the light more easily, so in fact, getting a good fit for a short extension is no problem. I would choose to do this over making a heel extension at a much greater diameter. Black nylon would be stronger than PVC, and durable hardwood such as oak would also be very good. Since the masthead needs to be capped in any case, this is as good a way as any.

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    Last modified: 22 Apr 2020 08:00 | Anonymous member
  • 22 Apr 2020 04:22
    Reply # 8920579 on 6872873

    Not to contradict David Th, but if you are concerned about weight and want the top to remain light, you also have the option of inserting a somewhat heavier plug into the bottom of your tube instead, and extending it a few inches. If the tube is already tapered, I would personally prefer the extended heel plug, which, by the way, would also be much easier to make. This is because the walls of the tube will be parallel at the bottom, easy to fit a plain round plug. But if the lamp pole is tapered, fitting an extension to the top is quite... well...  I don't even know you would do it.

    I agree with David Th, also from unhappy experience - it is better to have the mast too long than too short. If you need to keep your options open for retrospective changes, the bottom of the mast is easier to modify than the top, especially after you have made your masthead fittings. This, too, points to a wooden heel plug extension rather than a masthead extension.

    (The beauty of a wooden top section is when you just have a parallel-sided tube. The plug-extension is then easy to fit to the top, and you have the advantage of being able to put some taper into the top of the mast.)

    Last modified: 22 Apr 2020 08:21 | Anonymous member
  • 22 Apr 2020 03:48
    Reply # 8920534 on 8919967
    Anonymous wrote:

    My lamp pole arrived. For some reason the 25' pole I ordered is actually only 24' 8" long. Not sure what is going on there. I need to measure all the other dimensions to see if anything else is off. I have no idea how I could verify the alloy and the temper. I suppose I have already decided to just trust the vendor on that.

    At some point I determined that 24' was the absolutely minimum length for my mast. Hopefully that was correct.

    I am able to lift it and carry it around. It is not easy but I can do it.

    I am sure that if you find that you need a little bit of extra length that it will be quite easy to add a short timber extension to the top of the mast. This could incorporate the various mast head attachment points for halyards etc. I know from experience that it is much better for the mast to be too long, rather than too short.
  • 21 Apr 2020 21:22
    Reply # 8919967 on 6872873

    My lamp pole arrived. For some reason the 25' pole I ordered is actually only 24' 8" long. Not sure what is going on there. I need to measure all the other dimensions to see if anything else is off. I have no idea how I could verify the alloy and the temper. I suppose I have already decided to just trust the vendor on that.

    At some point I determined that 24' was the absolutely minimum length for my mast. Hopefully that was correct.

    I am able to lift it and carry it around. It is not easy but I can do it.

    1 file
  • 14 Apr 2020 14:34
    Reply # 8897866 on 6872873

    Thank you David Th. and David T. I hope you are both doing well during these unprecedented times.

    Your two comments read like echos of my own thoughts. First I would convince myself that wood soaked in epoxy and filled with stainless steel might actually be stronger than it was before. Then shortly after I would remind myself that my boat is not Speedwell of Hong Kong or Oryx so I can probably use lighter hardware.

    I will look for 3/8" threaded SS rod first. If for some reason 1/2" is easier to find then I will use 1/2".

    Thanks again.

  • 14 Apr 2020 07:37
    Reply # 8897425 on 6872873

    Pete was making tabernacles for larger, heavier, stiffer, ocean-going boats. I wouldn't use more than 3/8" studding on a 22ft boat intended for lake sailing. If set in epoxy, with large washers under the nuts, there can be no doubt about the overall strength of the assembly.

    Last modified: 14 Apr 2020 07:38 | Anonymous member
  • 14 Apr 2020 06:49
    Reply # 8897394 on 8896559
    Scott wrote:

    I am concerned about drilling 1/2" holes in four different places on the sides of the tabernacle. The boards I used are 2" dimensional lumber which is 1.5" actual thickness.

    I am trying to decide if drilling out a third of the thickness will significantly weaken the structure.

    Does anyone have an opinion to share?

    I think it will be just fine because you are gluing the bolts in with I imagine epoxy. So long as you get a good bond, the bolts, (threaded rod), will just become part of the timber. But this would be a good occasion to adhere to all working with epoxy rules.
  • 13 Apr 2020 19:35
    Reply # 8896559 on 6872873

    I have started thinking more about tabernacle details. I am following, as much as I am able, what Pete Hill wrote in JRA Magazine issue 61.

    The only concern I have right now thinking through the build is the size of the threaded rod that I will need to glue into the sides of the tabernacle.

    Pete recommended 12mm threaded rod for a sail approximately the size of mine. This works out to just about 1/2" in the freedom units we use here.

    I am concerned about drilling 1/2" holes in four different places on the sides of the tabernacle. The boards I used are 2" dimensional lumber which is 1.5" actual thickness.

    I am trying to decide if drilling out a third of the thickness will significantly weaken the structure.

    Does anyone have an opinion to share?

  • 03 Apr 2020 22:54
    Reply # 8878063 on 6872873

    I am still not sure why the sign at the store says '0.703" actual' if the nominal is 18mm (0.709") for this plywood. It seems like the 'actual' on the sign would be the nominal value.

    There are clearly bigger problems in the world right now.

    Evaluating risk of normal activities has become complex. For now, since our Governor has ordered everyone to 'Stay Home, Stay Safe' I am going to avoid going over to the boat storage.

    I will be working on cutting and shaping plywood for the mast partners here at home today. I am not sure what I am going to do when I eventually need a tool that I left on the boat.

    But yet the supplier for my mast, on the other side of the Lake Michigan, in Wisconsin, sent me an email. They claim to be able to keep up with any existing or new orders as normal. They gave me an expected ship date that is just about a week earlier than what I expected.

    Daily life is paradoxical right now.

    Last modified: 03 Apr 2020 22:54 | Anonymous member
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