SibLim update

  • 13 May 2020 07:12
    Reply # 8965266 on 8964488
    Annie Hill wrote:

    No David: your comments may be appropriate to someone who is desperate to get afloat and, for whatever reason, couldn't find a boat to suit, but if you are really so pragmatic about building and have money to employ labour and buy in, you would almost certainly, in this day and age, be able to find something that could be converted and would suit you almost as well.

    I am not sure which David these comments are aimed at. Certainly there are many boats out there which could be bought and converted to a junk rig, or just renovated to better suit the purchaser. Annie and I have built our boats for different reasons. She to get the boat that best suited her having being perhaps dissatisfied for various reasons with Fantail as her ideal liveaboard, cruising yacht, and not being able to find anything else she fancied for the money available (?). And what a boat Annie has ended up with. To have someone build that for her would cost so much more than what could be afforded. And I hope you have enjoyed the journey Annie.

    I began building my little catamaran as a project more than anything, but also chose the design because it seemed like the type of boat I would possibly like to down size to. After one and a half years of very part time building I was flagging a wee bit and getting to the stage of wondering whether the boat would ever get done. Then along came the Covid-19 lock down and I have spent almost 7 weeks full time boat building. I have seen rapid progress and enjoyed using my boatbuilding skills, and seeing the boat represented in the plans come to life. I am now only finish fiber glassing, painting and fitting out away from being ready to launch, and like Annie with her beautiful boat, I know I will have something unique and satisfying to me, and among the hundreds of either very old, or fiberglass boats available in New Zealand there just was not anything comparable for the sort of money I wanted to spend and which suited my idea of what a boat should be like, which included being built of wood. I am now back at work so progress will slow back to part time boatbuilding, so I may not be inside the two years construction time. I have been thinking over the past several weeks about the 'next one', but I am not sure that I want to put all that time and effort in again, maybe a dinghy next time!

    Last modified: 13 May 2020 17:19 | Anonymous member
  • 12 May 2020 22:28
    Reply # 8964488 on 8960485
    I'm not sure I could be described as a serial boatbuilder.  I happily assisted on the first, was dragged screaming and kicking to the second, and have only actually been credited with building this one!  However, what may be a self-evident truth to The Great One, is not so to everyone.  I know lots and lots of boatbuilders who have thoroughly enjoyed the several to many years they have put into the project.  Not everyone can afford to employ labour and buy components, not everyone wants to use the winter to do other things than build their boat.  Many people enjoy the journey as well as the destination: there is romance in creating a boat as well as in sailing her.  Indeed, if you don't enjoy the journey then you are really wasting your time.  How annoying to pop your clogs before launch date having resented the effort spent in the previous few years - not of course, that you would know about it.

    No David: your comments may be appropriate to someone who is desperate to get afloat and, for whatever reason, couldn't find a boat to suit, but if you are really so pragmatic about building and have money to employ labour and buy in, you would almost certainly, in this day and age, be able to find something that could be converted and would suit you almost as well.

  • 11 May 2020 09:29
    Reply # 8960485 on 4315719

    Words of wisdom indeed, from two serial boatbuilders. I believe it is axiomatic not to take on a large project of any kind that you can't complete in two years. Don't try to build something too big and complicated. Employ labour, buy components rather than make them, do whatever it takes, but don't get bogged down in the middle of a many-years-long project where you can't remember the beginning and can't yet see the end.

    Specifically, for boatbuilding: Two summers of hard work in good weather for the epoxy and paint work, with a winter in between for recovery and doing other things, and then a final winter for installing hardware, etc, and inside jobs such as sailmaking. If it's going to take longer, and the aim is to go sailing rather than to see if you can build a boat - buy one; it's less expensive and a quicker way to get afloat.

  • 11 May 2020 07:04
    Reply # 8960303 on 8958568
    Annie Hill wrote:

    James: building a boat is sheer insanity. But then so are a lot of things that give us pleasure. From my experience, as someone who was wondrously inept with tools and even now has huge problems with converting two dimensions into three, the main drawback of it, is that you have to devote your entire life to the project, if you ever want to complete the boat. If you are used to woodworking and competent, this would possibly be less of an issue. However, unless you are single, it’s probably not the most sensible thing to do. A spouse would either have to be equally enthusiastic about the project or extremely tolerant to be happy with the work, time and energy building a boat requires. I’m happy that I decided to do this, but would be less so if it were as a way to go sailing, rather than a culmination of many happy years afloat. Even so, I’m pretty much over it and would like to get my life back.  Chafe shouldn’t be a problem with the rudders, because the rope doesn’t move.


    Annie has shared some real words of wisdom about the boat-building gig. I once heard a saying; 'Fools build boats for other people to buy'. Building any reasonable sized boat takes hundreds or thousands of hours. Yes, a designer may say that the boat can be built in 800 hours, but even that is close to six months full time work. Building hours quoted are really just a stab in the dark, achievable perhaps with quick and nasty boat-building, or a highly skilled professional. For the rest of us building a boat is a real odyssey. So why do it? Perhaps it is the only way to get the boat you want for the money you have available. Maybe it is the satisfaction of creating something beautiful out of a pile of wood. For me it is the creative and technical challenge. Many construction dilemmas have been solved while unable to sleep at 1 am in the morning.

    While many non-builders may have lots of 'advice' to offer, it is the person on the end of the glue stick who has got to come up with a balance of what is the perfect way, perhaps, of doing things, and the sheer reality of the fact that there is so much boat to build, so many details to figure out, so in the end the builder tries to achieve the best balance between time and skills and material available, and hopefully always motivated by the dream and vision of this boat creation one day actually being in the water, anchored up in some beautiful cove, or skimming rapidly along the coast. But sometimes us boat-builders ask, 'remind me again why am I doing this'

    Last modified: 11 May 2020 07:05 | Anonymous member
  • 10 May 2020 14:44
    Reply # 8959040 on 4315719

    Ah, I see, you've got it the wrong way around, Eric. For zero lift, the boards would need to be toed out, not in - and then they might just as well be symmetrically shaped, as the camber would not produce any extra lift. All the references that I can find agree on toe-in, to maximise lift, they only differ on the amount, from 0˚ to 4˚. I gave Siblim only 1.6˚, because the more the toe-in, the more the sail power needed, and this is not meant to be a hard-driven boat, it's meant to be for more relaxed sailing.

  • 10 May 2020 13:47
    Reply # 8958929 on 8958728
    Anonymous wrote:
    Eric: no the boards are not toed in. I guess I shall just have to develop my biceps.

    I'm not sure what Eric meant there. Drawing a line from the mid point of the LE to the mid point of the TE of the board, it's at an angle of 1.6˚ to the centreline of the boat, so even though the flat outer face of the board is parallel to the centreline, there is actually that amount of toe-in. But this makes the boards harder to get up and down - in theory - because they are feeling more water pressure on them. In practice, it doesn't seem to make any difference. You use the weight of the board to get it down, when it's on the windward side, and the floatation to help to get it up as you tack, but in both cases, you do it when there is no hydrodynamic lifting force being generated.


    Bonjour Annie and David


    I will take as support the figure joined.



    For the cambered sail the figures shows that, in this example, the angle of attack that gives a 0 lift force  is - 3°.


    So to have no hydrodynamic drift (or opposed drifts between the two lowered dagger-boards) while motoring or sailing downwind the dagger-board should be toed in by 3°.

    If you don’t toe in the dagger-board, when you are leaving your morning with a significant current, when you try to lower the dagger-board, you’ll have a lateral force, a drift, that will apply an horizontal torque (the dagger-board can not rotate into the case) on the dagger-board that tends to squeeze the dagger-board (as when you want to rise or lower a dagger-board in a dingy while sailing windward).

    On other issue is that, when you are sailing headwind with both dagger-board down, if the dagger-board are parallel, if the drift is, let say 5°, the windward dagger-board (if down) will have an incidence of -5° + the 3° of offset and it will work « inverted » from - 8°. The profile doesn’t work properly at negative angle and it creates drag.

    On an asymmetric profile, the reference cord is the cord associated with the O lift. That cord should be parallel to the boat axis.


    For SibLim it might be possible to twist the dagger-boards in there cases by having a difference in thickness in the HDPE wedges. I don't know what profile was chosen but normally a few degrees of toes in should be enough.
    Eric


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    Last modified: 10 May 2020 13:53 | Anonymous member
  • 10 May 2020 08:12
    Reply # 8958728 on 8958568
    Annie wrote:

     Honestly David, the paint job as planned, has been on my ‘avatar’ for a couple of years now!

    Harrumph. it's a woman's prerogative to change her mind.

    Eric: no the boards are not toed in. I guess I shall just have to develop my biceps.

    I'm not sure what Eric meant there. Drawing a line from the mid point of the LE to the mid point of the TE of the board, it's at an angle of 1.6˚ to the centreline of the boat, so even though the flat outer face of the board is parallel to the centreline, there is actually that amount of toe-in. But this makes the boards harder to get up and down - in theory - because they are feeling more water pressure on them. In practice, it doesn't seem to make any difference. You use the weight of the board to get it down, when it's on the windward side, and the floatation to help to get it up as you tack, but in both cases, you do it when there is no hydrodynamic lifting force being generated.


    Last modified: 10 May 2020 09:16 | Anonymous member
  • 10 May 2020 03:20
    Reply # 8958568 on 4315719

    James: building a boat is sheer insanity. But then so are a lot of things that give us pleasure. From my experience, as someone who was wondrously inept with tools and even now has huge problems with converting two dimensions into three, the main drawback of it, is that you have to devote your entire life to the project, if you ever want to complete the boat. If you are used to woodworking and competent, this would possibly be less of an issue. However, unless you are single, it’s probably not the most sensible thing to do. A spouse would either have to be equally enthusiastic about the project or extremely tolerant to be happy with the work, time and energy building a boat requires. I’m happy that I decided to do this, but would be less so if it were as a way to go sailing, rather than a culmination of many happy years afloat. Even so, I’m pretty much over it and would like to get my life back.  Chafe shouldn’t be a problem with the rudders, because the rope doesn’t move.

    David D: I have no work ethic, I can assure you. Indeed, I have successfully spent the majority of my adult life avoiding work. To me it is a means to an end: to earn money. Once I had enough money for my tastes I made the money do the work so that I could go and do more interesting things.

    OK, Len. I get the idea. Our sockets have room for plugs and chargers. On the tiny screen of the tablet, I don’t think that there’s room for a keyboard and it’s certainly too small for even my hands to touch type. With the screen turned sideways, I can only see two or three lines of what I’ve written at one time, which I find very frustrating. I’ll buy a separate keyboard when we can finally go to the shops again. To be honest, it’s fairly low on my list of priorities.

    Graeme: I have seen the lashings and still don’t really get how they work. But I can see that they do, which is the main thing. However, I hope I can get them as tight as they will need to be for the heavy rudders that they support.

    The copper is one third of the volume, so 2/3 epoxy. The graphite about 10%. As Coppercoat reckons its product can be used over a primer with alloy or steel hulls, I can only assume that the copper that one exposes with the occasional brisk sand, is too little to cause a problem. It makes no difference to me, where the 1,200 kg of steel keel can fizz for a long time before being seriously affected. Shirley was advised to put carbon fibre and epoxy over alloy battens to strengthen them. The carbon has affected them and she has now dumped them for new, larger alloy ones. On the other hand, they were over 15 years old ... I don’t believe that there is any risk at all of galvanic action between the Coppercoat and the graphite, which is, anyway, out of the water. The graphite also makes the epoxy harder, which is a good thing for things that tend to get hit on occasion.

    David T: yes, the HDPE is slightly recessed and when we tried the ‘dry run’, there seemed ample room for the boards to slide up and down. They were a bit tight fore and aft, but the circular saw dealt with that issue. The wedges are only held with epoxy. My boat has no fastenings left if I can possibly avoid it. When I made the indents for the rudder lashings, I cut off the glass. Anyway, they are sealed in with epoxy and don’t move, so it’s essentially irrelevant. Honestly David, the paint job as planned, has been on my ‘avatar’ for a couple of years now!

    Eric: no the boards are not toed in. I guess I shall just have to develop my biceps. I have come across vacuum bagging, but never in such an ingenious way as the French have developed it. How does one hold the mating parts in place so that the pieces of wood don’t slip out of the way? I suppose a screw at each corner and then the vacuum. That would probably have been much better than my method – and I could have had an excuse to drink some wine! (And what a cute little plane!!)

    David D (again): You can’t get to the other side of where the wedges go: it’s a Void (scary!), but, as noted above, all the screws come out again. Quite apart from the cost and the weight of a zillion screws, I prefer to take them out so that in case of the boat being damaged, I can just take a saw, router or whatever to the damage and cut it out, without having to worry about hitting fastenings. Not wanting screws to penetrate the hull has occasionally made life more difficult for me: on the other hand, it has allowed me to finish the interior as I go, whereas if I had put the screws in from inside, I should have had to (re)paint those areas later. I would probably have run out of patience by then and not done as careful a job as I did.

  • 05 May 2020 10:35
    Reply # 8947442 on 4315719

    Hi, Annie.

    Really enjoying your boat build blog and just had a look at your recent progress.  

    Just reading that you screwed the filler wedges at the bottom of the bilgeboard slots to the skin with only 10mm of screw going into the skin.  

    If you haven't epoxied them into place and can gain access to the inside, it's normally better to screw through from the thin side to the thick side.  This allows longer screws for better grip and you could maybe  put a big penny washer under the screw head to help spread the load over the wider area of the thin skin. 

    I'm sure you have your own valid reasons for doing it the way you have and I'm not criticising in any way.  I wouldn't even have the courage or perseverance to start a build like yours, never mind do such a good job.

    Can't wait to see it finished and sailing.  Keep up the good work and excellent blog. 

    Regards.   


  • 03 May 2020 17:52
    Reply # 8943594 on 4315719

    Bonjour

    Great job !

    I don't know if it has been done on Siblim but with asymmetric dagger boards it is interesting to pinch inwards each dagger board a few degrees in order to have the neutral cord (the zero lift incidence ) of the dagger board parallel to the boat speed. It allows to rise or lower them when the boat is in motion more easily.



    To glue the bended surfaces of the dagger-boards there is a useful trick: the "vacuum cleaner" press associated to the red wine pressure gauge (so French). Once in place, the dagger board (for example) is wrapped in a plastic sheet. The edges are clamped loosely with cloth pins (there must be some leaks to cool the vacuum cleaner engine).The hose of the vacuum cleaner is introduced into the plastic bag. At the other end of the bag, a crystal flexible plastic tube is introduce and shaped in a vertical U. A little red wine is poored  into the plastic tube. The difference of hight between the two surfaces of the wine indicates the pressure.  10cm of wine hignt give a pressure of 100kg per scare meter. The remaining wine may be drink as a reward while the glue dries !


    Eric

    PS : The vacuum technique was invented by Mr Colomban to glue the aluminium skin of the Cricri's aircraft wing !


    Last modified: 03 May 2020 18:01 | Anonymous member
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