Swain BS_36 Stability curve

Discussion in 'Stability' started by junk2lee, Mar 9, 2011.

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  1. TeddyDiver
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    TeddyDiver Gollywobbler

    So you might be a good beach ball designer :rolleyes: How about doing that for a bean with a steel stick on the other side.. :p
     
  2. tazmann
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    tazmann Senior Member

    Didn't Haidan cut the tank out ?

    Nope my mistake it was the fuel tanks in the keel he cut out
     
    Last edited: May 25, 2011
  3. pdwiley
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    pdwiley Senior Member

    Hmm, interesting. My mental picture of the force vectors from a crash may be wrong.

    I think nearly everyone is going to crash into something hard sooner or later. Given my boat handling skills it's pretty much a given. That's why I'm building in steel.

    The nice thing about spending time in icebreakers was, you were *allowed* to hit stuff. Running down a lead at speed and making a turn, you'd do a bank shot off of the side of the lead to set you up. Good idea to remember there was some 80m of ship behind you tho and to be careful round meal times or the chief cook gave you his full & frank opinion of your driving skills. As I said, lotta fun though I don't miss it, BTDT.

    Woe betide any seal or penguin having a rest on a floe too.

    PDW
     
  4. HReeve
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    HReeve Junior Member


    No wonder there's so little evidence of BS36's having stability issues while under sail.

    The darn things spend all their time on the rocks!
     
  5. HReeve
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    HReeve Junior Member

    Wrong. The "C&C smile" occurs at the joint between the fibreglass hull and the lead keel. It occurred regardless of whether or not the vessel had ever been grounded, and occurred no where near the point where the trailing edge attached to the hull. It is easily prevented by annual checking of keelbolts, and the use of G-Flex or similar to fair the joint.

    I would hardly call this a high aspect keel.

    [​IMG]

    On the topic of C&C's, how many do you know that have ever had stability issues? For that matter, how many have sunk due to the "high aspect" fin keel been driven up into the hull and causing a breach.

    Of all the brands of production fibreglass boats to pick on, you picked what has to be one of the historically most overbuild brands out there. I would MUCH rather spend my $$ on a 30 year old production fibreglass C&C than any similar vintage steel vessel.
     
  6. Jack Hickson
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    Jack Hickson New Member

    What you need Troy, is a comparison. Now tape a doubloon to something flatter , like a beamy flush deck, like a sheet of styrofoam, and throw that in. It would take almost enough weight to sink it, to make it self righting, if you ever did get it to self right. This is a comparison between something round and buoyant to something flat and buoyant. More buoyancy in the middle ( like a trunk cabin, closer to the shape of a beach ball, or foot ball) and less on the edges, makes it much easier to achieve complete self righting ability, with very little ballast.. Less buoyancy in the middle and more on the edges undermines self righting ability( Like wide flush deckers, or the sheet of styrofoam)
    Yes, leading edges are pulled down in a collision , but for them to go anywhere ,the plate between the chine and centerline has to stretch, at 60,000 PSI tensile or 45,000 PSI yield . The plate at the trailing edges has only to dent, so it does the moving. The leading edges tend to be the pivot point.
     
  7. Jack Hickson
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    Jack Hickson New Member

    Haidan had enough ready built, free stainless tanks , he didn't need keel tanks.
     
  8. Jack Hickson
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    Jack Hickson New Member

    Pete . How many years did it take you to get to this stage? Looks like a week or two for an origami boat
     
  9. pdwiley
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    pdwiley Senior Member

    Hard to say because I really don't work on it full time and I go interstate for months. Less than a year for sure because it's only about a year elapsed time not working time. I probably only do 4-6 hours at a time too as my left arm is buggered from a bad fall and I'm left-handed.

    It's fair to say that it has taken me a *lot* longer than an origami hull, no doubt about it. However it's a lot stronger hull too and part of the time has gone into things like a compound curvature bow below the WL and separate bulwark plates. These things take a lot of welding.

    Some things I wouldn't do a second time, others I would. It's all a learning experience. If I build another hull, who knows what design I'd pick, maybe one that hasn't even been designed yet. An origami hull shape that had some decent transverse framing added is always a possibility, as is one of those Van De Stadt inside-out builds (but not with a reverse slope transom because I can't stand them). However I think I'm going to buy a set of plans for Tom Colvin's DOXY design, lots of space, heavy displacement and still shoal draft. Were I to build another steel boat of anyone's design (except maybe round bilge) it'd go a lot faster. You always have to pay your dues.

    I don't think any of us would argue that building origami fashion gets you a weathertight hull in a short time. Just that I don't consider that is the only valuable criterion, just one of them. I'm happy with my build to date and since the hull is basically finished now, there isn't much challenge left in the rest. Cabinetwork, plumbing and wiring are a piece of cake, done it all before.

    PDW
     
  10. Northman
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    Northman Junior Member

    I don't think anybody on this forum ever doubted that.

    And that is something only BS makes to a pivotal question. Every other boatbuilder, designer or NA here has pointed out that building the hull is the least time consuming part of the project.

    That's what this debate about the BS Origami way of boatbuilding is all about - again!:rolleyes:
    As usuall, BS has deflected any challenge to provide evidence for the basic calculations for his designs. No surprise since he has done the same on every other occasion: for framing (http://www.boatdesign.net/forums/classification/transverse-frame-calculation-32584.html and http://www.boatdesign.net/forums/metal-boat-building/welding-skin-frames-demystified-24066.html), construction in general (http://www.boatdesign.net/forums/metal-boat-building/origami-steel-yacht-construction-248.html and http://www.boatdesign.net/forums/metal-boat-building/good-bad-ugly-steel-building-methods-34211.html) or in this thread on stability.
    I'm with Peter on this. I like the basic concept for the BS boats as a simple and affordable way to building. I also rather like the rugged look. There are not many steel designs in that size with pilothouse out there. But before I would touch a BS boat I sure would doublecheck everything with a NA because BS has made it clear beyond doubt that his approach to boat design rests on learning by doing, guesswork and polemics.
    Regards
    Walter
     
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  11. Jack Hickson
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    Jack Hickson New Member

    Some prefer evidence and actual experience, like 30 years of trouble free cruising and surviving extreme conditions and torture tests, as evidence of a boat's structural integrity. Origami has it hands down, and is more than adequately proven by that standard. Others prefer to give paper calculations, and speculations, sometimes by someone who has never set foot on a boat, as "proof" of structural adequacy ,and value such unproven promises over actual experience. For those who prefer paper promises over the real world , such believers in naive assumptions should look for boats which are far less proven that origami boats, and should seek the paper promises they put so much stock in.
    Those who prefer experience over speculation should get their advice from those who have sailed long distances on the boats they are considering, not from armchair speculators who have never set foot on one, nor sailed anywhere in one. How tender is she? Go for a sail in a stiff breeze, among other types of boats, and find out .
    In BC, there are many BS 36 cruisers who have done everything from circumnavigations to circle Pacific cruises to back and forth across the Pacific. Go tell them that what they experienced was simply imagined ,as you know more about what they have been doing for several years than they do.
    There is no shortage of enough common sense, practical people, to keep origami construction continuing to take over small boat building, and eventually become standard practice for small cruising yachts.
    If someone is determined to seek out the most tedious means possible to get what he could easily do in a fraction the time, with far better results, using more modern methods , more power to him. They have a right to make costly and time consuming mistakes. It's their money and their time. Time is a dream killer in backyard boat building projects, so why add unnecessary work to what is already a long project. If a hull can be launched a month after the steel arrives and it takes another ten days to finish the detailing,another ten to paint her, a couple of days to rough the interior in and a week to get her sailing, then what percentage of the work is the hull and decks? What effect on the total would taking six months or more to get the shell together have ?
    How big a part of the boat the hull is, depends on how complicated you make the boat. If you ignore the designers suggestions for keeping things simple and inexpensive , then who's fault is it, if it goes over budget and overtime? Not the designers! Read the directions!
    What kind of answer could you expect from a designer who doesn't get the concept, and who's livelihood depends on making things time consuming and expensive , so the cost of design help is dependent on the number of hours billed for? Or from a designer who expects his clients to pay for his expensive lifestyle, by the number of hours he gets to bill them for? Who pays for his fancy design office with a view, his state of the art computers, new car, etc etc? The client does. Expect him to do his own sales pitch , not to pitch the ideas of his main competitors, especially competitors who show ways of reducing time and expense ,including design fees, and who's lifestyle requires far less income from his clients.
    If you are cruising the origami boats site, check out that posting by willyacht, may 28, 2001. It's one of the best posts I've seen on the internet , and hits the nail right on the head.
     
  12. Jack Hickson
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    Jack Hickson New Member

    Is the floor on the trailing edge that keel stronger than a half by 4 inch steel flatbar on edge, or a welded in steel tank?
     
  13. rwatson
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    rwatson Senior Member

    NORTHMAN - A very astute summary of the threads.


    Even more prefer BOTH. If one or the other isnt given what is the underlying problem ?

    Is it the inverted snobbery of a calculation illiterate amateur ? It is certainly coming across that way.

    Are you saying all designers are rich and live opulent lifestyles ? What severe trauma coloured your whole life to the degree that everyone else is an evil capitalist ? Or is it just a clever marketing trick to entice the poverty stricken amateur out of their retirement dollars ? This is just as bad as an overpriced consultant - you are just taking bites out of the other end of the wallet.

    This is really rich considering you had had numerous offers of having the stability calcs done for free - which you didnt take advantage of !

    There is the opposite end of the "ultra rich designer", and that is "the cheapskate, no service designer"

    Someone who declines to provide the basic calculations relating to a topics that lots very experienced sailors have come to grief on - stability - has some severe problems.
     
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  14. welder/fitter
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    welder/fitter Senior Member

    Walter's post "sums up" the reality of the situation. While it can be frustrating to, once again, encounter Brent's circular logic - this time in consideration of stability - I suppose that we have to accept that this is the most that Brent is capable of. To date, on these forums it has been shown that Brent is not the boatbuilder or designer that he pretends to be. As Brent often falls back on the argument that he has cruised for 11 months each year & that several/many boats built to his design have recorded significant offshore miles, perhaps, it is time to shine a light on the truth of these matters, but that belongs in another thread. For now, the owners of the BS36have enough reasons to arrange an inclining test in their local area, the results of which would be a reason to continue this thread. Fortunately, there are other designers of a similar method of boat construction - Tad Roberts, for one - who the builder or owner can have great confidence in knowing that the design will be well thought out from a person of both knowledge & experience.
     

  15. Northman
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    Northman Junior Member

    That shows the extend of BS' credibility. Mike Johns offered to do a structural analysis and pointed out that significant structural improvements could be made with nothing more than leftover material from building and a few hours more work. Tad Roberts did really impressive work with the stability calculations in this thread.
    So, instead of the highly overpriced working professionals ripping of their clients, here were two highly competent members of this forum offering to do the job for free that BS is not capable of doing himself.
    Each time BS does nothing but deflect the results that don't fit in his universe of unsubstantiated marketing claims.
    Since it doesn't seem possible for BS to accept anything but his own mantra, it should be pointed out in threads like this that everything BS has to offer has been shown to be wrong before.
    Regards
    Walter
     
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