SibLim update

  • 12 Jul 2017 22:13
    Reply # 4971500 on 4969399
    David Tyler wrote:You're both right, of course. The load when sailing is taken by the bottom of what I think of as the fender locker, but I understand is now the woodshed (Tys tie's fender lockers totally fill with water when hard on the wind in fresh conditions, and I was under the impression that wet wood doesn't burn as well as dry wood...) I was thinking of the times when I was short tacking with both boards down, and when the windward board was inadvertantly dropped. There was definitely some discernible movement, though of course Tystie has pivoted boards, which transmit forces through the pin, and Siblim doesn't.

    Your port side shelves will be fine.  Put something similar on the other side, and all will be well.

    The wood lockers are intended for wood that has just been brought aboard.  Quite apart from the fact that there is heaps of room under the foredeck for fenders (which will probably only be used at junkets, when someone wants to come alongside), I know from harsh experience that not very much wood takes up a lot of space until sawn into stove-sized lengths.  I shall have a box below for the sawn-up wood which can dry out nicely there (not that I have any intention of sailing hard on the wind in fresh conditions if I can avoid it!)  But putting newly-gathered wood in the deck lockers, will avoid bringing insects on board, and if any wood happens to have rot spores, they won't be finding their way below.


    I shouldn't have thought that even with both boards down, the windward one would put any serious loading on the inside of the box, but I shall certainly assume that you are correct.  I have an enormous capacity to worry and am now thoroughly discomforted with respect to the bilgeboards, so I am fitting an extra 12mm, shelf, at the same height as the stringer the deck lockers are attached to.  (From what I can gather from drawings showing the bilgeboard down, this is where the top will be.)  Well filletted to the bulkheads and board casing, I trust this will do the job, although the shelf below it will be somewhat less useful.  On the starboard side, as I said, I am fitting a fore-and aft counter, which is about 800 mm long and, fortuitously, at exactly the correct height.  With the bulkhead cut, coated and framed up, it would have been more than vexatious to have to start again on that side.  I can't put a similar set of shelves that side, because the passageway is already well to starboard of the centre line.  The amount of strutting and bulkheading in the heads compartment will put HMS Erebus to shame, when completed!

  • 12 Jul 2017 03:49
    Reply # 4969399 on 4969273
    Annie Hill wrote:
    ueli lüthi wrote: as the leeward board will take the big part of the forces. it's the outward side of the case that needs to be strong on bilgeboard top level – and there the hull should provide sufficient strength…

    utnik


    Well, I have to admit that this was my thinking, but I'm the first to admit to being totally ignorant about engineering stresses and very challenged when it comes to thinking about them.
    You're both right, of course. The load when sailing is taken by the bottom of what I think of as the fender locker, but I understand is now the woodshed (Tys tie's fender lockers totally fill with water when hard on the wind in fresh conditions, and I was under the impression that wet wood doesn't burn as well as dry wood...) I was thinking of the times when I was short tacking with both boards down, and when the windward board was inadvertantly dropped. There was definitely some discernible movement, though of course Tystie has pivoted boards, which transmit forces through the pin, and Siblim doesn't.

    Your port side shelves will be fine.  Put something similar on the other side, and all will be well.

    Last modified: 12 Jul 2017 07:36 | Anonymous member
  • 12 Jul 2017 01:16
    Reply # 4969273 on 4969252
    ueli lüthi wrote: as the leeward board will take the big part of the forces. it's the outward side of the case that needs to be strong on bilgeboard top level – and there the hull should provide sufficient strength…

    utnik


    Well, I have to admit that this was my thinking, but I'm the first to admit to being totally ignorant about engineering stresses and very challenged when it comes to thinking about them.
  • 12 Jul 2017 01:13
    Reply # 4969271 on 4969200
    Graeme Kenyon wrote:

    A good answer; I was just wondering, that’s all. I’m going for the high fulcrum myself anyway, for other reasons, and as you already know, that will work just fine. But one thing I do know – you won’t need 8 men to help you with the mast, although I can’t imagine any shortage of willing helpers. If you rig things right, you will be able to do it yourself. If you can pull up an anchor, you can raise a mast.

    Go for it Annie – don’t let anyone change your mind, only you should do that. I do enjoy and admire that faintly defiant tone of self determination in your posts – and what a great job you are doing.



    Well, as I say, I can still change my mind.  I could be wrong about the fulcrum height making any difference.  I would need to put a wedge at the foot of the mast in the tabernacle to ensure the water drains, but that's not exactly difficult.
  • 12 Jul 2017 00:27
    Reply # 4969252 on 4967090
    David Tyler wrote:

    Remember that the inner side of the bilgeboard case needs plenty of support at the level where the top of the board is going to rest against it.

    as the leeward board will take the big part of the forces. it's the outward side of the case that needs to be strong on bilgeboard top level – and there the hull should provide sufficient strength…

    utnik

  • 11 Jul 2017 23:50
    Reply # 4969200 on 4315719

    A good answer; I was just wondering, that’s all. I’m going for the high fulcrum myself anyway, for other reasons, and as you already know, that will work just fine. But one thing I do know – you won’t need 8 men to help you with the mast, although I can’t imagine any shortage of willing helpers. If you rig things right, you will be able to do it yourself. If you can pull up an anchor, you can raise a mast.

    Go for it Annie – don’t let anyone change your mind, only you should do that. I do enjoy and admire that faintly defiant tone of self determination in your posts – and what a great job you are doing.


  • 11 Jul 2017 22:46
    Reply # 4969113 on 4967087
    David Tyler wrote:

    Graeme and Ron,

    I tried, and failed, to persuade Annie set the tabernacle in the boat with the open side aft, and then to put the pin through the heel plug, where it can do no harm. Easy to do, and a no brainer where there is no coachroof to clear, as is the case with SibLim. And as you say, for occasional use there need be no pin. This arrangement has been used for centuries in the Yorkshire and Northumberland cobles, and would work well here, too.

    To me it wasn't a no brainer.  The SibLim mast isn't a short, stout stick like on a coble, and I'm unlikely to have half a dozen stalwart men to help me get it down. And Pete preferred the arrangement that we went for.  By having the fulcrum a little further up I think you have a little more control.  I prefer, in this instance, to go with what I know and with what I have used in the past.

    But as Graeme says, should I (or the rest of you) change my mind, I can always reverse the tabernacle!  It's not installed yet.

    Last modified: 11 Jul 2017 22:53 | Anonymous member
  • 11 Jul 2017 22:43
    Reply # 4969109 on 4967090
    David Tyler wrote:

    Annie, 

    Lots of good thought going into the heads compartment, this is looking very fine.

    Remember that the inner side of the bilgeboard case needs plenty of support at the level where the top of the board is going to rest against it. On the port side, the shelves are going to do that, so make 'em strong.

    I can't figure out where the battery is going to go now?


    Er, your drawings don't show this and I don't recall you ever mentioning it.  There is a C-head to port with an athwartships counter and your original drawings showed a heater on the other side.  The newer drawings show a C-head going right out to the bilgeboard case, with a small counter forward.  Nothing on the other side.  As it happens, I intend to put a decent counter on the starboard side and have a fore-and-aft bulkhead inboard of it.  It so happens that the counter has ended up at the same height as the stringer on which the bottom of the 'fender locker' rests.  But the shelves on the other side - which also have a fore-and-aft bulkhead inboard of them, have been fitted for heights according to what is going to be stowed on them.  I can, I suppose, remove the top one, put a small, but thicker one higher up and fillet it all in.  Perhaps you would like to tell me what you had in mind before I go ahead and fit what I've already made.

    The battery is going under the cabin sole on the starboard side.


  • 11 Jul 2017 11:10
    Reply # 4967236 on 4315719

    The KISS tabernacle hinge.

    If the mast has to swing over the top of the tabernacle as mine will have to (because I have a cabin top/dodger in the way of the lowered mast) – and as Annie might have to do now, because the tabernacle is made – then I think the simple answer is to just put the “damn big pin” through the tabernacle instead of the mast. (Shove it through the back plank of the tabernacle as near to the back of the mast and as near to the top of the tabernacle as possible, have a couple of inches sticking out both sides and that’s it, finished. The pin is static and acts like a horizontal belaying pin – might even be useful for that. When lowering the mast just lash it to the pin with a simple square lashing (with a bit of slack so it won’t bind up when the mast swings – and maybe rig a preventer against the mast slipping down) and that gives you something like the arrangement which Ron has just explained. (Thanks Ron – nice to find someone else has done the same thing.)

    Now a step away from KISS but an improvement – make a strong neat fitting which attaches the pin to the top of the tabernacle, at the back of the mast, so the pin is mounted about a rope’s thickness higher than the sides of the tabernacle. A nice little engineering challenge for someone with metal-working tools – or better still, just take a enough off the sides of the tabernacle so they are a rope's thickness lower than the pin. The main thing is, the pin is attached to the tabernacle not the mast – and now the square lashing can be made as good and tight as possible. The pin itself is now the pivot point for the back of the mast, and the pin centre is the centre of rotation. The lashing will then rotate around the pin together with the mast, all secure and with no binding up. I think this is what I will do, and I will complicate things even a little bit further by setting the pin back a little from the mast so there is room for the pin to carry a stout rubber roller. A tight square lashing around the mast and the two ends of the pin, the mast bearing on the rubber roller – and that’s the hinge – and when the mast is down it can roll forward still being supported – the gallows at the back having a roller as well.

    The pin can stay in place all the time, not too obtrusive, and maybe handy the rest of the time if you need to belay a halyard or some other line at the mast –  or swig against it – or hang your hat on it.

    Now for the real KISS. I think David has hit the nail right on the head – with the tabernacle  open at the back, the mast can go up and down and will never slip forward or slip out of the tabernacle, and you don’t even need a pin (at least, not for the hinging function) Why didn’t I think of that? I remember in the forum when it was mooted, and thinking at the time Annie’s right, why would you pivot the mast at the heel? I have had a number of little boats with hinges at the heel of the mast and always found the system to be rubbish – so had a pretty strong prejudice, and was blinded by it. But this is different. This is a proper tabernacle we are talking about here. For me, the penny has just dropped – with a flush deck boat why would you not do what David suggests and then you don’t need a hinge or a pin or even a lashing for the raising and lowering of your mast. That’s KISS. Pity its no good for me, because I need to get the pivot point up as high as the cabin top or dodger. But Annie, just out of interest, why did you not like the idea of making the heel the pivot point for the mast, in your (SibLim’s) case?

    I shouldn’t be suggesting to someone who knows much more than me how to suck eggs, but at least I have got David on my side, so I will boldly suggest that it looks to me as though you could still change your mind if you wanted to, just by facing your tabernacle round the other way when you get around to mounting it. (Like any boat builder, you must be driven nuts sometimes by unsought bystander advice – but never mind, you are in the same league as Joshua Slocum now, and he got through it!)


    Last modified: 11 Jul 2017 22:37 | Anonymous member
  • 11 Jul 2017 08:07
    Reply # 4967107 on 4966751
    Graeme Kenyon wrote:

    Annie, your blog has given me hours of interesting reading, but I had forgotten about it lately. Now I find you have described the making of your tabernacle - wonderful - I have wanted for some time to come and visit you to have a look at it, but reluctant to interrupt your valuable boat-building time. Now I don't have to, its all in the blog! (By the way, your link did not work for me, but your blog site address is easy to remember.)

    There's an 'e' missing from the URL.
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