a better tiki 21

Discussion in 'Multihulls' started by guzzis3, May 7, 2019.

  1. oldmulti
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    oldmulti Senior Member

    The problem in KSS and other methods is how much do you want the perfect hull shape? Glass can take a limited amount compounding especially if it is thin glass skin thin foam cored. KSS can produce a great hull shape as long as you cut darts in it and delete foam at high bend areas. BUT you then have repair the dart cuts and fill in the solid glass area's to reinforce the hull. KSS big advantage is having a finished exterior surface that you then have to fair after you have repaired the darts you cut. Rob Denny in some of his earlier proa's did some glass bending on hulls and it worked OK as long as it was done at the right time of curing. He eventually changed to creating a simple hull shape full mold technique that allowed the layup of a complete hull in one shot. Please don't simplify something to create a lot of work for yourself. A suggestion. If you are building a woods Sango and you want a foam glass version create a simple mold for the hull above the turn of the bilge as per the hard chine version then do as Thomas Firth Jones did on his original Dandy design, create a small curved mold for the bilge shoe that he attached to the rest of the hull as described in his "New Plywood Boats" book.
     
  2. redreuben
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    redreuben redreuben

    I haven't tried it of course, but I have done a lot of fibreglass work, my intuition is telling me as soon as the darts start moving away from the cored area you will just end up with a series of flats.
     
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  3. oldmulti
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    oldmulti Senior Member

    Redreuben built glass boats for a living at one point, his experience is valuable.
     
  4. guzzis3
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    guzzis3 Senior Member

    Yes I know.

    I was just wondering if there was a quicker easier or less scary method. My whole thought on the tiki 21 was how you would achieve a better or equivalent boat for less money and time. If _I_ were building it I'd probably do as you suggest, cast to the waterline either in solid, foam or strip then use flat panels to get the required flare with a fair surface, tabbing the panels and just glueing them on to the bilge. But that scares people. The only reason people build V hulls is they think they are saving time. The hull skins aren't the problem, it's the death by a thousand cuts that follow.

    What I am suggesting is completely omitting the core from the waterline down, just infusing the outer skin, then as the panel is double curved snipping transverse cuts in that skin to take out any buckling. The glass would slide over itself so you'd have little wedges of double thickness, which is trivial to fair out later. The question is could these cuts get you a fair smooth result. If they sit against the mold fairly then you lay up extra solid glass thickness inside.

    This has nothing to do with wizzer/sango. The only proper way to build that boat is either fully cast foam, strip or the hard chine ply or flat panel foam option. I really don't think you could mix and match.

    BTW I did try and get a price on paulownia the other week. More than double the price I can get pvc foam for. Given it adds about 150 kg and is probably slower unless you are building a bright finish it's hard to justify.

    Anyway thank you for the thoughts.
     
  5. redreuben
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    redreuben redreuben

    For an improved Tiki 21 hull I would use 4mm tortured ply, think Tornado. If you are set on a foam glass boat just use the bilge section as a female mould and set it in female frames and yes just make the shoe. Resin coat the ply in waxed polyester and finish to the standard of your choosing.
    Do the whole thing in vinyl Ester
     
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  6. rob denney
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    rob denney Senior Member

    Sorry for the delay, I was not following this thread (thanks for the heads up, Luke).
    Glad you like the boats. The mini cargo ferry is not 'styled', at all. It is the most possible boat for the least effort and money. It had to be easy enough to build that someone could build one, then return to his/her island and show others how it is done. It also had to be cheap, buildable with a minimum of tools and no fastenings, a payload of 1 ton/tonne, able to sail upwind and generate no plastic waste. The latter is why it is ply and not Intelligent Infusion. In the competition to choose it was a Wharram style cat, which did not come close to meeting these requirements.
    A "traditionally styled" cargo proa would be easy enough to design, but it would add build time, weight and cost and sail worse. I'd note that the Wharram look is a recent, and short lived 'tradition'.
    Give me a couple of weeks to get the rig sorted on the prototype mini cargo proa I have just built and come for a sail (Runaway Bay, an hour south of Brisbane). It doesn't look 'pretty', but I doubt you could build anything of similar speed/payload as quickly or as cheaply.
    Rwatson, The rig and steering was chosen as it is what the locals are used to, is cheap, easily built and repaired and less likely to be damaged. Windsurfer type rigs (and 'proper' rudders) would cost more and, although easier to shunt, are not as easy to remove and stow.

    Couple of other things from this thread, based on my experience:
    Epoxy is so close to the cost of vinylester that Ve is not worth the trouble (secondary bonding, curing, age limits, stink).
    Pitching is not a function of equal volume ends. It is the product of the added buoyancy from immersion of the ends x the distance from the centre of pitch. This distance increases (moves closer to the stern) quicker on an unrockered hull than it does on a rockered hull. The longer the hull, the straighter the rocker and the shallower the draft, the lower the pitching. However, there is a combination of wave height and period that will start any hull pitching. The longer the boat, the less likelihood of meeting the specific combination and different length hulls tend to dampen it. This is one aspect of why a 'traditionally styled boat' with overhangs, rocker and a V hull would be a worse performer than the zero rocker, double ended, maximum length hull of the mini cargo ferry.
    Overhanging bows in waves react more sharply than vertical stems as the impact is diffused. Wave piercing bows take this a stage further, but need careful design and weight watching.
    Fibreglass does not compound unless it is bent before full cure, which is possible, but scary and needs a full mould. It seems like it does (ie, you get a large sheet and support it on a single point, it appears to compound) but when you put a batten on it, you discover it bends, but doesn't compound. Cored fibreglass will, but it does so by deforming/crushing the core. Not a problem in low stress areas, a serious one in high stress.
    Based on the 2 workshops harryproa sponsored KSS is a great way to build compared to other conventional methods, but is still a lot of fairing and no compounding.
    Tortured ply is a lighter and easier way to build a hull than ply, stringers and frames, if you have or can get the panel shapes right. Applying wet resin by hand is a wasteful, time consuming and health damaging way to build a boat.
    A poor upwind rig will not be helped much by an efficient upwind leeway resister and vice versa.
     
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  7. Dejay
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    Dejay Senior Newbie

    I quite like the "no-style style" of your boats. Form follows function. Beauty is in the ease of the builder?

    I wish there were more reviews of builders who have build with your intelligent infusion approach. I still have zero experience but from what I've read it really sounds like the smartest approach. If I wanted to build a sailboat I'd most likely build a harry proa. But woe to those who pursue unusual ideas :)
     
  8. guzzis3
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    guzzis3 Senior Member

    I was referring to the Harryproas generally. As I've said to you before if you or anyone had a catamaran designed using the intelligent infusion system I'd be up for building it. Such a lovely system. But I love cats so I can't come at proas just as I struggle to get enthusiastic about tris.

    As I said I was asking a different question. This isn't about being sensible. I just remain surprised no one has tried to out wharram Wharram (see what I did there ? I made him a verb :D ). Acorn and Mr Toad are good solutions to teh small cheap easy cat, but given the success of the Tiki 21 you;d just think someone would have copied and hopefully improved on the idea.

    Anyway..

    A poor upwind rig will not be helped much by an efficient upwind leeway resister and vice versa.

    Have you had any experience with crab claw rigs ? are they terrible to windward ?
     
  9. BlueBell
    Joined: May 2017
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    BlueBell Ahhhhh...

    Guzzis3,

    I believe you are the one to design and build a better Tiki 21!

    I would suggest sticking with the general shape but lengthening it.
    Using infused foam if that floats your boat.
    Lighter, longer, faster, better.

    Note: You realize a proa is simply a modified cat, right?
     
    Last edited: Jul 2, 2019
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  10. rob denney
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    rob denney Senior Member

    Woe, indeed! ;-) Best way to find out about Intelligent Infusion is to buy a cheap vacuum pump, materials, a sheet of window glass and have a play.

    Guzzi,
    I sailed on a very well built and fitted out (carbon/kevlar hull, nice sail, etc) crabclaw rig in Germany several years ago. It was dire. Weight shift steering required me to hang off the lee hull stern with my legs in the water, leeway (assymetric hulls) was appreciable, pointing poor, made worse by if you pinched too high the rig fell down to windward.

    However, the guys who did the investigating into the boat required for the Marshall Islands did a lot of sailing with the local experts and reckon the rig works well. One of them built a model which sailed pretty well, including tacking through 80 degrees.


    Based on this and the mini cargo ferry having a crab claw (they apparently prefer the term 'ocean lateen') as that is what the locals know and use on their race boats, I built a test boat with an ocean lateen rig and a lee board. 2 x 6m booms at 60 degrees made from top masts of windsurfer rigs, a main mast from old tubes I had lying around and a tarpaulin sail duct taped then sewn. As expected, the main mast was too flimsy, and is being beefed up. Should be sailing in a week or so.
     
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  11. redreuben
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    redreuben redreuben

    I don’t see length as the problem that’s easy, add 100mm to each frame spacing. Shape is the issue, torture the sides more, add daggerboards and foil shaped rudders, a transom you can walk up, waterline length, some thoughts put into headroom. Either cabin rising from bow or more freeboard or.....

    Harryproas, start another thread though it’s been done to death.

    In a nutshell great concept that has never been properly demonstrated, at least to my satisfaction.
    I was fired up by the Bucketlist program but it just petered out into a half assed effort that went nowhere.
    Intelligent Infusion, same.
    Great idea but has never been clearly demonstrated from go to whoa, from flat table to finished boat.
    I’m not sold on the bulkheads glued into slots to me it still seems like snap on dotted line.
    Happy to be proven wrong.
    I haven’t met Rob Denny but have great respect for his ideas and enthusiasm, I just wish he’d finish something before moving on to his next inspiration!
     
  12. guzzis3
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    guzzis3 Senior Member

    Mr Denney,

    The model sails well, but good reaching and running is no surprise. The last shot of it sailing to windward was the most interesting for me. Perhaps the trick to a good oceanic lateen is good design. I have wondered for a while if the failures of A frame masts on cats, large foresails and OL rigs have had a lot to do with aspect ratios. A lot of them seem to end up being low aspect and that will always yield poor results on a multihull...

    Redreuben,

    I thought quite a few harryproas had been built and are sailing ? I guess there are no online videos showing II from start to finish but I am pretty sure the boats have been built.

    I had though 23' was a reasonable loa with a waterline about 20'. As you say freeboard is the issue with the tiki, not just for accommodations but bridgedeck clearance...
     
  13. Dejay
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    Dejay Senior Newbie

    The website mentions FEA engineering so I would assume that includes laminate schedules of the actual skin geometry and should give a high confidence estimation of those areas. I'm just curious Redreuben, assuming done properly, would you consider that good enough "proof"?
     
  14. redreuben
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    redreuben redreuben

    Dejay,
    In theory there is no difference between theory and practice.
    In practice there is.
    I’m a practical person.
    Mate I used to glass boats for a living, foam sandwich, vacuum bagged, epoxy, vinyl Ester, all sorts.
    I think intelligent Infusion sounds well thought out, undoubtedly clever and will save a lot of mess. But no wet laminating at all ?
    Call me a cynic but I just think it’s being a tad oversold.
    I’ll go and read the latest info and see if that changes, I haven’t really looked at the site since the first animations went up.
    Meanwhile Tiki 21’s yes.
     

  15. oldmulti
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    oldmulti Senior Member

    Just to add a little extra to this. There have been a few glass and foam glass Tiki 21's built, the globe circling Cooking Fat the most famous. The hull structure of one Tiki 21 was 225 gram cop strand mat, 1708 biax, 9 mm divinycell foam, 1708 biax on the inside all done in vinyester resin. This would be a strong hull and probably could be built lighter with sensible internal fitout reinforcing a lighter hull structure.
     
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