Building RYD-16.9 Rocky - Hull 21

Discussion in 'Boatbuilding' started by John Theunissen, Aug 5, 2017.

  1. PAR
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    PAR Yacht Designer/Builder

    Be careful John, you've built on the heavy side, so start thinking about reducing weight where you can. The clamp can tolerate some heft, but there's other elements that can be lightened or reduced in dimension, so you can gain back some of the weight you've lost in other areas. Nice number of clamps you have . . .
     
  2. John Theunissen
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    John Theunissen Junior Member

    Ahh..Paul, you found me out - that naturally conservative engineering approach with a safety factor on top. Needless to say you are right, and I’m thinking about how I might reduce weight in the construction after the bulkhead installation stage, which is then progressively less structural in nature. Any ideas welcomed.
    I’m considering combining the rubrail and the toe rail into a single laminated structure.
    I’m also scratching my head about attaching the bowsprit compression posts to the bow stem as it looks like I should have bolted them in before planking the hull - I’ve an idea that should work so will sketch that out and post a comment with it.
    Regards, John
     
  3. John Theunissen
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    John Theunissen Junior Member

    Paul, just following on from the last post, here is my suggested way to secure the compression posts to the bow stem.
    Regards, John T.
     
  4. John Theunissen
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    John Theunissen Junior Member

    13A28F8A-BBDE-4A59-8278-ACAC79745908.jpeg Oops, too quick on the button...
     
  5. John Theunissen
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    John Theunissen Junior Member

    ACF08CEC-7E23-4689-A033-9C58E766CCA3.jpeg Here’s what I’m thinking about for the combined rub-rail and toe-rail.....but it will add more weight. Perhaps best to use an aluminium strip for the toe-rail.
     
  6. PAR
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    PAR Yacht Designer/Builder

    No need to over think the compression post. In fact I suspect the bulkhead will do fine in this role, but the post on the back side will carry the loads to the keel. I'd just half lap it and put a couple of through bolts through it and the lower stem.

    The sheer clamp and the rub are simply 1x2's, though the rub could be dressed a bit, with a cove, tapered bottom, etc. Your drawing seems to show considerably more material than the two 1x2's sandwiching the planking, the plans show. Is this the case or is this just a laminate of thinner stock? If it's the laminate thing and the dimensions aren't too much bigger than spec'd, then I'd say go for it.
     
  7. Angélique
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    Angélique aka Angel (only by name)

    The interior could have a structural support function too, so best ask the designer before making any changes there, either in position or dimensions or scantlings of these items.

    Good luck, and thanks for sharing all the info . . :)
     
  8. John Theunissen
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    John Theunissen Junior Member

    Thanks Angelique, that is very wise, and I have one of the best designers in the business (I’m biased of course)!

    Paul, the laminate construction uses thinner stock so the overall thickness is around 22mm (3x7mm plus glue) for both the sheer clamp and the rub-rail so it is consistent with a 1x2 solid piece of timber - that should be ok.

    Thanks for your advice over the compression posts, I do tend to ponder some of these things a bit more than I should. I’m not sure that I can achieve a through bolt arrangement with the lower stem - there simply doesn’t look like enough space there to drill/thread the bolts. I like your lapping idea, so will do that, together with a bolted wooden bridge above as shown in my earlier diagram.
    Regards, John T.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Yeah, it's pretty tight down in there isn't it. Epoxy bonding will do. The real key to the compression post, is that it's square with the vertical load over the stem. Focus on this and you'll be fine.

    I too like to laminate pieces that tend to bend in multiple directions. Springing in a piece that just bends around is easy enough, but once some twist or compound gets in, then it's easier to laminate from thinner stock.
     
  10. John Theunissen
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    John Theunissen Junior Member

    2C770F5F-B8FF-4B8C-ABB8-96DF43EF4E0A.jpeg Greetings,
    Engaging my wife in the project, even if it is only to show the proportion of the hull.
    I have started with the filleting and taping of the interior seams and tackled the bow stem over last weekend. Achieving the perfect constituency of the epoxy mix is challenging - the starboard side was a little too soft so I had to nurse it in the near vertical segment for a while before it stayed in one place and the tape went over fine. On the port side I was determined to have a stiffer mix but it wasn’t, despite me thinking it was before starting to apply it. Anyway, I was a bit too confident and in too much of a hurry to apply the tape and so ended up with some unequalness in the joint. I need to learn to put into practice what I read on the forums - wait for the epoxy to gel before applying the tape! Lesson learnt.
    Regards, John T.
     
  11. PAR
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    PAR Yacht Designer/Builder

    You don't have to wait for the epoxy to gel, though this can be helpful on vertical and overhead surfaces. One of the keys to getting these non-sagging mixes the right consistency is to spread it out thin, on a non-porous surface as you add filler materials. This is because the thin mix will delay the exothermic process much longer, then if the goo is in a pile. I spread it out so it's less than an 1/8" thick at any point on the mixing board. I use several things for this but scrap pieces of Formica work good. With the goo spread out, just take the Formica (or whatever) to the work and being spread out so thin, it makes picking up goo in uniform amount really easy.

    If you apply what seems to be thickened enough goo to a joint, seam, whatever, it becomes massed up, so the exothermic process accelerates and this causes the goo to thin out a little and sag. Judging this is all experence, but can be quickly learned after you screw a few fillets. I usually apply tape right after I have a length of seam filleted. I have precut pieces of fabric ready to go and once I have filleted enough area for several of these pieces, I drop on the fabric. This takes some planning, but not particularly hard to accomplish. This assumes you will quickly get the fabric down and likely also apply neat epoxy over it. I first lightly smooth the fabric over the goo, which partly wets it out, then the neat goo goes on.

    Kind of you to provide sufficient padding for the little lady. Those look similar to the ones I have on the shop floor, to save my back, while standing on concrete.
     
  12. John Theunissen
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    John Theunissen Junior Member

    Thanks Paul,
    I have never thought about doing it that way, and it makes a lot of sense.
    My technique up to now has been to mix the thickened goo in a plastic tub (about 500ml capacity), spoon it into a double layer plastic bag (sandwich bag), cut off a corner and dispense it like piping cake icing. I find that this at least places the goo where it needs to go, and then I can shape it as needed....but it suffers from exactly the points that you make about speeding up the chemical process and making the mixture more fluid.
    I’ll give your method a try. Hopefully I can improve my placing of the goo where it needs to go, otherwise its going to be a bit of a mess.
    Regards, John T.
     
  13. PAR
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    PAR Yacht Designer/Builder

    My method is granted a little more messy, but once you get a handle on how to "play" with epoxy on a plastic applicator, putty knife, etc., you can really "toss" it around. The pastry bag approuch, I know many love, but I've cooked way too much goo using this method, because I wasn't fast enough to get the huge mass out in time.

    Everyone that uses epoxy learns the usual lessons, like mixing well, proper ratios, etc., but then develops their own techniques. Some of these, are simply preferences as to how to do things, like the pastry bag thingie. Others might include how to make really neat fillets, the dry or wet fabric lay down, etc., etc., etc. None are incorrect though with practice, some do seem to work (for you) better and with more predictable results, which is the real goal.
     
  14. Angélique
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    Angélique aka Angel (only by name)

    John, there's very sad news with the sudden passing of Paul.

    I wish you strength to process this news, and the same to his loved ones, friends, other builders of his plans, and fans, of which I became one.

    Please keep on posting on your build thread, as I'm sure that would make him happy, and perhaps the forum will take over some of his guidance,

    See the sad news thread: RIP Mr. Paul - PAR - Riccelli

    Vale Paul . . :(
     
    Last edited: Jun 2, 2018

  15. John Theunissen
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    John Theunissen Junior Member

    Thanks Angelique, that’s very sad news indeed! My sincere condolences to his family.

    I’ve been off-line since the end of May so have only just seen the RIP thread. Absolutely concur with the many positive comments and eulogies given in his memory.

    Paul was the main reason I’m building Rocky - A couple of years ago I had already bought plans to build another boat but continued to have some reservations. I had always admired and appreciated Paul’s posts on another forum, and then realised he had a range of his own designs - I fell in love with Rocky and Paul was amazingly supportive. I will miss him dearly as I continue to build. Hopefully I can do justice to his design, and will continue to post the progress.

    In Paul’s absence I will be happy to welcome any comments and forum support along the way.

    Blessings, John T.
     
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