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A 7 metre variant of SibLim

  • 02 Dec 2018 14:47
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    Reply # 6941957 on 6010674
    Anonymous member

    The tabernacle completed far enough to install this bulkhead. The block at the bottom bears the heel of the mast, and extends forward, tapered to match the foredeck, so as to link the tabernacle strongly to the foredeck. Later, blocks with semicircular cutouts to match the mast (38mm dia) will go at top and bottom of the recess.

    Making up the cabin headlining (1). The area to the left will be cut away to form the companionway.

    Making up the cabin headlining (2). The area to the left will be cut away to form the companionway. The companionway slide will run on top of this piece.

    [It probably isn't clear what I'm doing here, but I hope it will become so when I set it in place.]
  • 02 Dec 2018 07:55
    Quote
    Reply # 6941734 on 6941644
    Anonymous member
    Annie wrote:

    It's all very clever, David, but I can't help wondering how you are going to do this in full scale.  How are you going to handle these enormous sheets of joined-together plywood - it's hard enough dealing with one full sheet, from my experience.  How are you going to be able to spread the glue without it starting to kick off at one end before you have even got to the other?  And you can't move things to different angles for ease of access in the full-size version.

    Just wondering.

    The first of these large tasks is putting in the longitudinal berth/cockpit fronts. Only a few tab and slot joints need to be assembled at once, so the gluing is not difficult. It's just a little glue to be put onto the sides of the tab and into the slot. When they are holding things firmly, the filleting can be done at leisure. It's just the weight and general unwieldiness that's an issue to be addressed. I think it's solved by enticing a couple of mates with talk of beer and BBQ afterwards. Otherwise, in the internal structure, there's nothing bigger than your bulkheads.

    The bottom panels are thin and narrow, so not too much weight involved. They would be long and fragile if pre-assembled, so I propose to put them on after section first, then forward section/bow transom, making up the puzzle joint in situ (much as you did with your hull panel scarphs). Two layers of the bottom like that, then the third as a final operation once the middle panels are in place. When I get to the topsides and middle panels, these will be put on dry, with just one tab for fore-and-aft location and cable ties elsewhere. The cable ties will be loose, while epoxy is worked into the gap between bulkhead and panel, then tightened up. Again, I think it's a three man job for an afternoon, so there will be talk of chilled six-packs and snags on the barbie as an inducement. Then the filleting and glassing can be done at leisure.

    Last modified: 02 Dec 2018 08:28 | Anonymous member
  • 02 Dec 2018 06:12
    Quote
    Reply # 6941709 on 6941644
    Deleted user
    Anonymous wrote:

    It's all very clever, David, but I can't help wondering how you are going to do this in full scale.  How are you going to handle these enormous sheets of joined-together plywood - it's hard enough dealing with one full sheet, from my experience.  How are you going to be able to spread the glue without it starting to kick off at one end before you have even got to the other?  And you can't move things to different angles for ease of access in the full-size version.

    Just wondering.

    When I built my Tiki 30 I dealt with 9 meter long sheets of plywood in a variety of gluing operations. I don't recall it being too difficult, but I did need to be organised! The biggest single gluing operation was attaching the 9 meter long top hull panels to the lower  hull panels. I had help with that and I do remember some fairly frantic mixing of numerous batches of epoxy and glue powder.
    I have recently being looking at how RM yachts in France assemble their large plywood hulled yachts, as a way of learning something more about plywood/epoxy composite boat-building. They manage very long sheets of plywood, admittedly in a factory situation, but there is a lot that can be learned from the experts. Slow hardener in winter?  

    I imagine a lot of the 7m Siblim would be stitched together before gluing, and a lot of coving and filleting? I like the idea of minimising the timber framing and putting the plywood together with stitch and tape methodology. If I build another boat after this current project I would like to be a bit smarter about the way I connect the sheets of plywood. Once I complete the hulls of this catamaran I am going to try and use a lot of weight minimising stitch and tape wherever I can.

    Anyway, back to the sticky epoxy!

    Last modified: 02 Dec 2018 07:14 | Deleted user
  • 02 Dec 2018 04:34
    Quote
    Reply # 6941644 on 6010674
    Anonymous member

    It's all very clever, David, but I can't help wondering how you are going to do this in full scale.  How are you going to handle these enormous sheets of joined-together plywood - it's hard enough dealing with one full sheet, from my experience.  How are you going to be able to spread the glue without it starting to kick off at one end before you have even got to the other?  And you can't move things to different angles for ease of access in the full-size version.

    Just wondering.
  • 30 Nov 2018 22:09
    Quote
    Reply # 6940563 on 6010674
    Anonymous member

    After the epoxy had set, the wedges came out without any trouble.

    Adding the tabernacle to stn 1 bulkhead.
  • 29 Nov 2018 14:01
    Quote
    Reply # 6937872 on 6010674
    Anonymous member
    http://www.junkrigassociation.org/resources/MemberAlbums/2757889/SibLim%207%20metre%20-%20model%20at%201_4.25%20scale/P1030192.JPG

    The strongback, 4880 x 1220 x 300 high at full size, with square hole forward to accommodate the tabernacle.

    http://www.junkrigassociation.org/resources/MemberAlbums/2757889/SibLim%207%20metre%20-%20model%20at%201_4.25%20scale/P1030193.JPG

    The central section of deck, located between angle brackets. Cutouts for companionway, forehatch and tabernacle.

    Deck stringers glued on, carefully aligned with forward end of central deck.

    Athwartships framing at forehatch.

    Athwartships frame to limit forward movement of companionway slide.

    Temporary strut to hold after end of deck stringers at the correct spacing.

    Deck stringers glued to central section of the deck.

    Stn 1 bulkhead, bow former and foredeck filleted together.

    After face of stn 1 bulkhead, showing tabs, slots and wedges glued and assembled.


    Last modified: 29 Nov 2018 14:10 | Anonymous member
  • 28 Nov 2018 16:42
    Quote
    Reply # 6936607 on 6010674
    Anonymous member

    This boat is to be built, not only upside down but also inside outwards and last things first. So it's needed some head scratching to determine the order of assembly. Today, I did a complete dry run of the setup. It went well. There were some small errors, which are not serious and can be corrected before the full size version is built. Some operations are a bit tricky, and I don't know how easy it will be to manage them at full size. A two-person job, anyway.

    Gary, you were right about the wedges. I need a lot of them, it's a tedious job to cut them out, and now I have an idea what size they need to be, I can add them to the CNC job.


    3 files
  • 24 Nov 2018 09:01
    Quote
    Reply # 6930341 on 6010674
    Anonymous member

    The topsides.

    That completes the puzzle joint assembly (except for the side decks).

    Now it's time to start setting up.

    1 file
    Last modified: 24 Nov 2018 09:02 | Anonymous member
  • 23 Nov 2018 09:12
    Quote
    Reply # 6929397 on 6010674
    Anonymous member

    Middle hull panels and upper topsides

    Bottom panels and a bow transom. At full size, these will be three layers of 6mm plywood with staggered joints.

    2 files
  • 22 Nov 2018 09:32
    Quote
    Reply # 6928523 on 6010674
    Anonymous member

    The second puzzle joint gluing session, which went better than the first; I used colloidal silica rather than microfibres, and plenty of heavy engineering bricks to hold the parts flat.

    Central piece of the deck, with forehatch cutout
    The longitudinals that form the cockpit, settee and galley sides
    Deadwood final layer
    Deck stringer, that also forms overhead handholds in the cabin

    [GRP straightedges to check alignment]

    1 file
    Last modified: 22 Nov 2018 09:35 | Anonymous member
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