A 7 metre variant of SibLim

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  • 06 Feb 2019 22:06
    Reply # 7150742 on 7149601
    David Tyler wrote:

    Heavily modified, of course, and his photo gallery shows some interesting ideas, particularly the companionway.

    That looks similar to Mingming II Companionway without as much bridge deck. I like the fire brick on the stove to help the heat stay in the boat longer when the stove is on. I would think it radiates a lot better than the flame gasses. (for some reason my spaces are working this time) I found it hard to see much else in the way of mods but I don't know the boat well to begin with...
  • 06 Feb 2019 09:42
    Reply # 7149601 on 6954893
    David wrote:
    Annie wrote: Well, I'm not sure how prudent I am - my form over the past couple of decades would appear to indicate the opposite if anything - but if the 7m variation can sail around the world, then taking my 8m to Fiji (as I have tentative plans to do) seems less than foolhardy.

    Hey, you might as well dream while you build.

    I wouldn't for a moment want to claim that the SibLim 7 can sail around the world. Only that it should be able to tackle the easier "milk run" trade wind passages across the Atlantic and South Pacific. Size does matter, bigger is better, more is more (BibMim), when the height of breaking waves is more than the beam of the boat is when knockdowns become more likely. As the GGR entrants are demonstrating, 32 - 36ft is a bit marginal for going nonstop south of the Great Capes. 40 - 50ft boats have a rather better track record, eg Hawk, sailed by Evans Starzinger and Beth Leonard, 47ft LOA.

    I would say: dream on, but happiness is adjusting your dreams to realities and practicalities. Yes, SibLim 8 can go to Fiji, as could SibLim 7, but I would hesitate to take either down to Stewart Island. Can SibLim 7 sail from Japan to NZ? According to World Cruising Routes, it could be somewhat of a windward slog to get out to Guam or the Marshall Islands, so the rig had better be pretty good, but then it should be easier on the SE trades past Vanuatu.

    Well, I might have to rethink that.

    The OCC 2018 Awards have just been announced, and the Jester Award has gone to 

    Szymon Kuczynski, Atlantic Puffin

    For his 270-day non-stop singlehanded circumnavigation via the three Great Capes, in a boat of only 6.36m (just under 21ft) LOA and with no outside assistance, a new world record. Click here for more information.

    His boat is a Maxus 22, which is very similar to my Hunter Sonata/Duette and is only rated CE Category C.

    Heavily modified, of course, and his photo gallery shows some interesting ideas, particularly the companionway.

  • 04 Jan 2019 21:26
    Reply # 6983893 on 6010674

    Sure, Len, this is a helpful observation and immediately brings up an idea or two, on how to get around the problem.

    Again I must say though, that it is a method being worked over to suit a boat smaller than this 7M design.... specifically the 5M one mentioned in the other thread about the 5.7M SibLim derivative.

    As you say though, it would be a good thing to work this out on a model, so the final build size is not of that much importance.

    Last modified: 04 Jan 2019 21:30 | Anonymous member
  • 04 Jan 2019 18:53
    Reply # 6983681 on 6982994
    Jeremy Walker wrote:

    At 2M beam, 1/2 beam distance is reachable(with my average length arm as a distance quage), and when one or other of the halves is theoretically flipped to face inside upwards.

    Joining the halves on the centreline, should make the flat workshop floor a convenient flat building bed, on which to  lay the bulkheads and frames-- with the CL horizontal and the waterline vertical.

    I think this is one of those ideas that would need to be modeled. The normal thought (from planking days) has been to put panels on both sides at the same time (or one on one side then one on the other) rather than doing one whole side and then working on the other. The reason given is to keep the stresses balanced on both sides and the craft straight. Doing the build in halves, I would see the hull panels trying to fan the halve bulkheads out as the hull panels try to remain remain flat. Now from origami or stitch&glue building, it can be seen that joining panels already gives shape. I think that where the centre line is put on the floor there would have to be a strong back affixed to the bulkheads to keep it straight until ready to be joined with the other half. I had first thought of anchoring the half to the floor but doing so would take away the ability to turn things over for inside work. The centre hull panel would have to go on last as part of the joining process and would need to have access from the inside for glassing. I think some doubling of structural components may be needed too. Yes, there would have to be a centre hull panel I think even if it was only 200mm wide. If one really wanted a pointy front end, I think a wedge would be mounted over that.

    If it was a usable system, I don't think 2 metres would be a limit. Though it needs to be remembered that the half would still be 2 metres in one dimension.

  • 04 Jan 2019 11:38
    Reply # 6982994 on 6010674

    Although the 5.7M SibLim thread is the apt one for my following suggestions, there could be some value WRT the 7M version... where building is done in the way of filleting, glass taping, and also epoxy painting the interior, whilst still in the early stages of exterior sheeting.

    It should work out to be flipping modules, so that access is possible to all corners, while standing with feet on the workshop floor.

    At 2M beam, 1/2 beam distance is reachable(with my average length arm as a distance quage), and when one or other of the halves is theoretically flipped to face inside upwards.

    Joining the halves on the centreline, should make the flat workshop floor a convenient flat building bed, on which to  lay the bulkheads and frames-- with the CL horizontal and the waterline vertical.

    The topside planking/strake, is bent over and onto(the bulkhead frame structure), as the first sheeting step, with the  chine and the deck/sheer lines being the guides to a fair lay of the panels.....perhaps I do not fully appreciate the details of pre-cut panel construction, but surely accurately cut panels wired together along their edges, should produce a fair curve?

    Stringers and battens strategically placed between the chine will then help to support a fair assembly.

    I would like to see a template panel of the arched deck, used as an assembly aid, and possibly with a small log on the inside edge of this deck template/panel. This, as well as the chine, should create the coreect and fair shape shape?.

    Surely a chine log would not be needed, and double bias taping inside and out would be all that is needed, to create a stiff enough hull piece, that can flipped over for working the inside?

    Last modified: 04 Jan 2019 11:48 | Anonymous member
  • 03 Jan 2019 11:58
    Reply # 6981337 on 6010674

    Before I stow the part-built model away for the time being, here's what it looks like right way up:

  • 02 Jan 2019 17:59
    Reply # 6980062 on 6978522
    Gary wrote:

    Now while I feel there is still some to learn about the final skinning of this vessel, it probably won't be learned other than at full scale. I am also mindful that David Tyler is a scarce resource (only one of him in the whole world apparently) and I would not want to think about him contemplating how many puzzle joints can dance on the head of a pin when he could be working on his new improved soft wingsail or answering the loads of other interesting queries that come his way.  

    I think I'm going to act on that, and lay the model aside pending further impetus to take it further. Building a hard chine plywood hull is not new technology, it's been done for years in many different ways which can be employed here, according to taste.
  • 02 Jan 2019 03:42
    Reply # 6979419 on 6010674

    Couple of things here - Without vast experience in plywood sheeting, the work done has gone Ok (working alone) by having a ledge to place/locate the sheet, then turn in one screw to fasten and prevent movement of that edge.Then the sheet is progressively bent over the frame/stringer structure, with more screws turned in to arrive at a fair panel.Slots and tabs with wedges would obviously aid the process

    As for preference of wood over alloy masts  -- when I was  not yet aware that an alloy of say 6061 with a T6 temper was up to the task , a grown spar was chosen and proved to have been a good choice, both in performance and price.

    Now I would probably buy the alloy tube and trust its integrity.

    Still, before forking out on such a thing, I would make a timber box section wooden mast with internal composites reinforcement (If I had the shop facilities to do so), or (if a tent was a make-do option) I would do epoxy infusion of long S glass inside  thin wall alloy tubes that have been TIG welded together, making up the required length.

    This way, the made-up composite wall (inside the alloy tube) can be made thicker near the partners, and can also have a taper where the wooden topmast piece is inserted.

    Last modified: 02 Jan 2019 04:01 | Anonymous member
  • 01 Jan 2019 06:44
    Reply # 6978522 on 6976845

    I did the rough fairing of the chine logs on Annie's Fánshì (as we must now learn to call her) using an electric plane. It took quite a while, and I made buckets and buckets of shavings. On the model, there's less physical work, but it's harder to work accurately. I'd like to get away from that, but retain the fairness of having solid timber there. So I went back to the Gougeon Bros and looked at their stringer-on-frame method. They put 1 1/2in x 3/4in stringers on edge, to get the maximum stiffness, and therefore fairness, using the least material. I think we can do that here:

    I have been thinking about this quite a bit. Chine logs are a bit of a pain to fair and poorly done can also lead to wobbly chines. I was thinking that something like the above only using ply, notched into the frame. Alternatively GB's stringer could also be readily notched to assist frame edge placement / stability. A stringer however is also stronger and easier than ply to get a fair result. And if its in the Gougeon brothers book its probably been tested a zillion times. Incidentally their book has been a free download for some time now:

    https://www.westsystem.com/the-gougeon-brothers-on-boat-construction/

    I agree with David on Topsides first, and I particularly liked his idea of "hangers" incorporated in the frames from which to hang them. that should ease their installation dramatically. Once hung they will sit patiently awaiting wire or cable ties or whatever. 

    I am curious about why Jeremy is happier with a timber mast than an alloy one. I _think_ I read recently that Michael Storer says the performance of a box section mast is better than a birdsmouth and lighter than alu. (hope I am not misquoting him). He does mostly do dinghies however. Then again C-Tech in In-Zud seem to be offering almost affordable rices for carbon: http://www.carbon-tube.com/index.php 

    Really don't know about butt joining the bottom a piece at a time. I would have thought that it would be easier to get a fair twist with a contiguous piece of ply, but if the butt joints landed on something substantial with a good deal of overlap its not going to be a big deal to do and the outside is glassed anyway so for sure there is more leeway. 

    On the topic of cleanup and clamping being required for puzzle and scarf joints then its hard to see it being terribly different amounts of work, and having just built all my kitchen worktops from 45mm wide hardboard planks I can attest to the prowess of the Makita BO6050J which will make cleaning up anything fairly trivial. So I am still inclined to use puzzle joints where applicable.

    Now while I feel there is still some to learn about the final skinning of this vessel, it probably won't be learned other than at full scale. I am also mindful that David Tyler is a scarce resource (only one of him in the whole world apparently) and I would not want to think about him contemplating how many puzzle joints can dance on the head of a pin when he could be working on his new improved soft wingsail or answering the loads of other interesting queries that come his way.  




  • 31 Dec 2018 20:21
    Reply # 6978217 on 6977744
    Anonymous wrote:
    Jeremy wrote:

    Seven metres length and 2.5M beam is more than my garage space will allow, but I have just heard that David has a 6M design as well ...

    Well, that might be overstating it a bit. In response to a query about a size to fit within a 20ft shipping container, I had a quick look to see that it was feasible. I think it is, with  sizes of 5.7m LOA, 2.2m beam, 2.2m maximum depth. But that's as far as I've taken it, and would need a serious declaration of intent to build, and then a design brief (as with Annie and Gary) to take it any further.
    Thanks for that David.Although max beam and height dimensions of2M would be about all I could manage, because of the door aperture, and Maybe there are others with similar restrictions, so a micro SIBLiiM thread could possibly be a way to get around to putting out ideas on this.
    Without moving toward thread drift, it might cover that last suggestion by admitting that the complexity of two drop boards and rudders are design features of SIBlim that I am grappling with.So, losing the 0.5M beam at the same time as inserting a single case for a lifting ballast keel is what underscores/mitigates the loss of beam proposal.



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