SibLim update

  • 06 Feb 2021 14:08
    Reply # 10065596 on 4315719

    Ah, no, this can't be the latest version, but I'm unable to go back into the Freeship model and check it at the moment. One thing that I'm sure of is that Annie let me add 50mm more draught,  3 layers of steel plate instead of 2, so the ballast is all external, a bit lower, and its weight is 1200kg.

  • 06 Feb 2021 12:45
    Reply # 10065452 on 4315719
    Anonymous member (Administrator)

    Thanks, David for the numbers, most interesting.
    I notice that she shares some main dimensions with the Alo 28, Johanna. She have about the same length and beam in the waterline, and almost the same displacement.
    The difference is that Johanna has 1400kg finkeel and the SibLim design has about 40cm wider beam over all than the Alo.

    From the numbers it appears that the outside keel is 791kg and then there is 400kg inside ballast. Was FanShi actually built this way?

    Another thing; the vertical CB of the whole underwater body is given as 0.41m.
    Then the vertical (z plane?) COG of the whole boat is 0.761m, or well above the waterline. Does that mean that she is unstable within the first couple of degrees heel? Practical sailing has already shown that this is not a problem. I am just curious if the description ‘corky’ could have something to do with this.


  • 06 Feb 2021 08:16
    Reply # 10065218 on 10063585
    Arne wrote:

    ‘Corky movement’
    I think that is a result of the detail I like most on FanShi. It is my view that David has chosen just about the best mid-section you can have on a shallow-draught boat. It ensures a narrow boat in the waterline (dimensions, please) for good light-wind performance, and then, as the boat heels, the wide ‘cheek’ ducks under and the centre of buoyancy literally jumps sideways and stretches the righting arm. Excellent! In addition, this section helps to lower the cabin sole for better headroom. The slightly ‘corky’ movement is a little price to pay to get a seaworthy boat with shallow draught.

    Congratulations, both to the Builder and the Designer!


    Hydrostatics results are attached, for all the dimensions and ratios.
    1 file
  • 05 Feb 2021 19:03
    Reply # 10064089 on 4315719

    The motor is a 4-stroke, 6hp Nissan/Tohatsu.  I wouldn't have a 2-stroke motor.

    I cleaned the carburettor very carefully before using the engine.  I also filled the tank with new petrol.  Anyway, it now seems a lot happier.  I guess like all of us, it just wanted care and attention!

    David has drawings of the self-steering gear, on the website.  At this stage, I cannot praise it too highly.  It is far better than any servo gear I have lived with.  I wonder if 2 rudders and 2 trimtabs help with this.  There is a lot of power from those big trimtabs and they are always fully immersed.   However, I haven't used it in heavy conditions, so cannot say that i have thoroughly tested it.

    Yup.  I am perfectly happy with a bit of lee helm in very light conditions.

  • 05 Feb 2021 15:33
    Reply # 10063585 on 4315719
    Anonymous member (Administrator)

    Lots of interesting stuff by Annie and David, below.

    Lee helm:
    It appears that Annie has sorted this out well enough. Since tacking goes well and the wind vane copes, it is probably no big deal. I suggest you leave it as it is, Annie until David have designed SibLim 2 and 3 etc. and tested them. My own Johanna had lee helm in the same conditions as FanShi, and I hardly noticed it. Some noted it when sailing her in the JRA rallies in Stavanger  -  but they didn’t blame Johanna for being slow or difficult to sail.

    Asymmetric helm
    Only on my Malena have I noticed this. My guess was that on starboard tack, with the sail undistorted, the CP was sitting further forward of the geometric CE. This was expected to happen on Johanna as well, but I was unable to detect any differences. My hunch is that the (welded, distorted metal section) rudder, which pulled slightly to starboard, neutralised such tendencies when tacking under sail.

    Directional stability.
    To me there is no such thing as too good directional stability as long as tacking and harbour manoeuvres go well.

    ‘Corky movement’
    I think that is a result of the detail I like most on FanShi. It is my view that David has chosen just about the best mid-section you can have on a shallow-draught boat. It ensures a narrow boat in the waterline (dimensions, please) for good light-wind performance, and then, as the boat heels, the wide ‘cheek’ ducks under and the centre of buoyancy literally jumps sideways and stretches the righting arm. Excellent! In addition, this section helps to lower the cabin sole for better headroom. The slightly ‘corky’ movement is a little price to pay to get a seaworthy boat with shallow draught.

    Self-steering gear.
    I hope Annie will produce a real write-up, with sketches, photos and a few numbers. I bet many more than I are impressed that the brand new FanShi was launched with a brand new, home-made wind vane, which worked from Day One.

    Is that a four-stroke or a two-stroke? Since it appears to behave better and better, it may well have had problems with sludge in the carburettor from old petrol. I have seen coughing, spluttering outboards getting a new life after the carburettor has been taken off, opened and given a good rinse. And a new spark-plug, of course. My own 4-stroke, which I start some 30-60 times a season, but which only runs long enough to burn 2-3 litre, is kept happy by running on alkylate petrol.

    Congratulations, both to the Builder and the Designer!


  • 04 Feb 2021 10:06
    Reply # 10060758 on 4315719

    Before this topic is wrapped up, and thinking about the hoped-for SibLings rather than the now completed FanShi:

    1. Probably the mast's forward rake should be reduced by about 2˚- that would bring the CE aft and lower the clew.
    2. Or a higher peaked yard, as per Arne's planforms, to bring the CE aft, reducing the balance area a bit.
    3. Maybe the skegs could be smaller, to move the CLR forward, but I don't think that would help much.
    4. Maybe the boards could be toed-in by a degree, to give them more lift and reduce lee helm, but again, I'm not convinced.
    5. The whole design could be stretched to 9 metres LOA, on the same bulkheads, to make her slimmer and even more easily driven, and to add length to the berths for a taller crew.
    6. I could think about changing the construction to use CNC-cut, slot-together internal elements, as on the SibLim 7 design, for a higher budget, shorter build time project.
  • 04 Feb 2021 04:56
    Reply # 10060455 on 4315719

    Whew!  What a lot of comments, advice, critiques and ideas; too many to deal with, in truth!

    I haven't concluded this thread until today because I wanted to have more time with the boat, and I've also happily been in places with poor Interent connections.  If anyone responds to this post, I shall try to reply, but as SibLim is now FanShi, I think the thread has run its course.

    Firstly, let me deal with the only negative that I have found: the lee helm.  After trying all sorts of different variations, I finally concluded that what was needed was to move the sling point about 18 inches further forward.  The top of the sail doesn't set perfectly, because the natural inclination of the yard is to sit at mid point, but it doesn't look too bad.  Today Alan and I fiddled with the LHP which is now a bit of a cross between a THP and an LHP, going from the top sheeted batten back to itself and then down to a block.  Set up with a reasonable, but not excessive, amount of vigour, it removes most of the creases; but the sail is more or less in the same place as it was in its previous setting, which I have now used on a couple of passages, covering about 40 or 50 miles in total.  Yesterday I deliberately went out in very light airs and spent a fair bit of time on starboard, which is where the lee helm is/was most apparent.  It is still there up until an honest F2, when it gradually disappears.  Indeed, close-hauled in F3 I could leave the helm to look after itself and the boat sailed herself.  I would guess she was sailing a bit more freely than ideal, but the real point is that she kept on course.  I think all the junks that I have been shipmate with had lee helm in very light condtitions, and I am now perfectly happy with that aspect.  The only other drawback, to me, is that the boom is very high aft.  Alan can easily reach it, but I can't.  That, in combination with the extreme camber, does make it difficult to work on the rig.  I anticipated this to an extent and have the lazyjacks made off on cleats, with an eye in the end so that I can bend on an extra line and lower the sail down to a sensible level. 

    So what else?  The boat is very stiff and has an unusual, corky, buoyant motion which reminds me a little of sailing a catamaran.  It seemed very odd at first, but I am quickly getting used to it.  She doesn't seem inclined to roll unless hit by a big wake, bang on the beam when the motion is as violent as it ever gets and things might even fall over.  Generally they don't!  I haven't observed her at anchor in any amount of wind, from another boat or from ashore, but on board she feels as though she doesn't sheer around too much, and she certainly doesn't sail to the end of her cable, lean over and then head back the ther way.  Or at least she doesn't appear to, which is the main thing as far as onboard comfort and a sense of security are concerned.

    The bilgeboards are easy to use; I don't think I get them as deep as David intended, but they seem more than adequate and FanShi - so far - has tacked without the slightest hesitation.  Generally, they are quiet at anchor, unless it is very choppy, when little waves slap and crash in the boxes.  Underway they are also quiet except in a beam sea when the noise can be quite appalling as they rattle and crash.  However, if the board is raised properly it becomes a lot quieter and I am starting to think that when the lee one starts rattling, it is a hint that it's no longer doing anything and I might as well haul it up.

    The balance in the sail, even though now somewhat reduced, makes for a soft gybe, as I had hoped.  I'm happy with the weight of the yard - it brings the sail down easily, but is no effort to raise.  I just hope that it is strong enough to stand the sling point being moved forward.

    The boat tracks amazingly well, even with the boards up, but she is very sensitive to being overcanvassed and protests strongly if that happens.  I reckon she and I are both happy to take the first reef at the top of F3 and the second and third come pretty quickly after that.  I would say that the strongest gusts so far have been about F6 where she would really like to have 4 reefs.  I like the shallow angle of the yard.  My only concern is that they boat is perhaps too easily driven: I am a nervous sailor and don't really enjoy sailing at much over 5 knots.  However, I have no intention of going out and looking for strong wind, either!

    The self-steering gear is absolutely superb.  It starts to work as soon as the boat is ctually moving with the wind, is sensitive and so easy to adjust  - much better than the complexity of a servo-pendulum.  The first time I tried it out was sailing down Whangarei Harbour with the lightest of breezes from dead astern.  It held us on course without a problem.  Originally there seemed to be too much friction, but I unlocked the trim tabs for 48 hours and let them swing back and forth and that seems to have sorted it out.

    As for the poor, much-maligned engine, I have to say that having given it a couple of good, long runs, it seems to have decided that it might as well co-operate.  Having squeezed the bulb and pulled the choke right out, I usually start it after 2 or 3 pulls.  I can't say it takes much effort to turn it over.  At first I needed to play the choke very arefully, but now I can just run it with the choke pulled out less than 10mm and after 3 or 4 minutes push it in completely.  It idles more and more smoothly each time I use it  I shall treat it to a new spark plug when I get the opportunity!

    There is still, of course, lots and lots to learn.  I don't really know how she goes to windward and certainly not in anything of a chop, but I'm happy with what I've seen.  Overall, I think David has created something that ticks all the boxes.  Indeed, I rather suspect that, with my penchant for reefing sooner rather than later, her sailing potential will be wasted on me. I'm sure she could surprise more than a few people in the local regattas, if I were prepared to push her.  SibLim is completed and at this stage, I really hope that some sisters are built very soon! This seems like too good a boat only to have one incarnation!

  • 02 Feb 2021 19:33
    Reply # 10056589 on 4315719

    I see that there's a new, long entry in Annie's blog, detailing the sailmaking process, and then going on to the story of the launch (which we know about, and have seen some photos of, but there are more photos here).

  • 26 Jan 2021 04:21
    Reply # 10033070 on 4315719

    Thank you Graeme (and Zane) for posting the videos. I had the great privilege of being there and enjoyed it all immensely - you have captured the event perfectly. What an amazing job Annie has done building Fan Shi.

    I do hope Marcus keeps Freebie - as we know he gets such pleasure out of using her. 

    Thanks again.


  • 25 Jan 2021 20:48
    Reply # 10032249 on 4315719

    Graeme, that's wonderful. Thanks so much for putting it together, and for posting where we all could see it.

       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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