High Power Very Small Tri(s)-10'-14'-why not?

Discussion in 'Multihulls' started by Doug Lord, Jun 27, 2010.

  1. Munter
    Joined: Jul 2007
    Posts: 285
    Likes: 11, Points: 18, Legacy Rep: 125
    Location: Australia

    Munter Amateur

    Hi Doug,
    Multiple issues with your proposed design have been noted over the previous pages. Simply repeating the same information and pictures of boats you have previously already posted within this thread does not make these problems go away. You are considerably underestimating the mass, you have no solution to the problem of leeway and you haven't addressed the concerns I raised in my last post over the impact of downward pulling foils in respect of this increasing the loads on the boat (other than cutely including reference to a maximum RM in the mindlessly repeated piece of creative writing above - how will you ensure the RM does not exceed this amount? Ejector Foils(tm)?).

    The discussion does keep going around in circles. You keep asserting a design breakthrough, I raise issues with the design, you dismiss these with either an invalid or simply no methodology and then you repeat your performance assertions. You end up back where you started simply because you have not generated anything that actually takes you anywhere. Present something with substance and based on reality and perhaps the discussion can move forward.

    Its interesting to have a look at the links to the two boats you post above. Compare their stats to the ones you propose. How much do they weigh? Both weigh more than your target mass despite one being shorter, both being narrower and both carrying about half the sail area of your imaginary boat. Nor do they appear to be capable of flying on a single hull, further reducing their specification. OK, they are only built from organic carbon instead of the presumably space grade stuff in your design but don't these figures seem problematic to you? Imagine how heavy they would be if their beam was stretched to 14 feet, the rig size was doubled, foils were added and then two lounges thrown on top? All the data points in the space show a likely mass far higher than you are assuming.

    Rather than repeating the same text proclaiming a design breakthrough how about you actually address the multiple design issues that completely undermine your proposed design?

    With respect to the comment on the mocking manner. You completely missed the point in the rush to refute it. I was telling you that it was inappropriate to mock somebody's tertiary education. You incorrectly interpreted that as criticism of mocking in general which was not the point. It doesn't really matter but it is another example of your determination to refute rather than read and understand. For what its worth, I'm comfortable with the comments I have previously made in this thread.
    You also seem to consider quoting my comment on being condescending as making some kind of point. I guess it shows the capacity for a little self reflection and I don't consider that to be anything to be ashamed of. Frankly, I find your posts asserting design brilliance condescending as they assume the reader will put aside all logic, reasoning and independent design evaluation and simply believe the absurd claims you have repeatedly made.
     
  2. Alex.A
    Joined: Feb 2010
    Posts: 348
    Likes: 9, Points: 0, Legacy Rep: 108
    Location: South Africa

    Alex.A Senior Member

    1 person likes this.
  3. Doug Lord
    Joined: May 2009
    Posts: 16,631
    Likes: 312, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Class 10

    -----------
    Alex, thank you very much! Found a lot of good information and some cool pictures.


    Rules

    Length over all (LFT) Not exceeding 10 ' - M.3 , 048
    Width not exceeding M.3 ( multihulls )=9.8'
    Sail area may not exceed 8 sq.m=86 sq.ft.
    ------------------------------------
    10' tri weights

    Central hull 12 kg=26.4lb
    amas 4x2kg(?) = 8 kg= 17.6lb
    + 3.3 kg comes rudder 7.26
    Sailing(?) 3.8 kg= 8.36lb
    mast + boom = 10 kg=22lb
    Bars(?)= 3 Kg=6.6lb
    towels few grams
    ---------------------
    Tot.barca armed 40.1kg=88.2lb
     

    Attached Files:

  4. Munter
    Joined: Jul 2007
    Posts: 285
    Likes: 11, Points: 18, Legacy Rep: 125
    Location: Australia

    Munter Amateur

    Hi Doug,
    You haven't actually adressed the queries, you merely assert that you have. For example - what about the issue of the foils providing downforce that increases the righting moment during gusts? Your previous comments were that the boat could be lighter than a Weta because it had less righting moment. I have put forward a common scenario where I think the righting moment would be higher than you suggest and rather than address the issue you have simple charged on posting the same creative "I was walking on a deserted beach and made an amazing discovery story". I raised it a couple of posts ago and there has been no response at all.

    Your calculations re mass using a laminate weight are a good step but how did you come up with the area? What are the assumptions? Without some kind of explanation it appears you have just picked two numbers to arrive at a pre-determined conclusion.

    Don't get indignant, just come up with answers instead of excuses.
     
  5. Doug Lord
    Joined: May 2009
    Posts: 16,631
    Likes: 312, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    -----------------
    I have answered every legitimate issue raised. You might try rereading some of the stuff above. Other than that what I can say is that I disagree 100% with your uninformed interpretations of my information. And your condescending attitude and personally insulting rhetoric is something I won't deal with,period. I've been into boat design and building for 45 years, have designed and built dozens of boats from scratch and therefore, have a great deal of confidence in what I have presented. You have repeatedly, and obviously, ignored a number of very key points and "discussion" with you is not worth the time and effort.

    see post#70,again
     
  6. Munter
    Joined: Jul 2007
    Posts: 285
    Likes: 11, Points: 18, Legacy Rep: 125
    Location: Australia

    Munter Amateur

    Hi Doug,
    Simple copy paste doesn't really move your position forward. It is merely avoiding dealing with the questions. If you had addressed the problems why wouldn't you just put a succinct summary instead of avoiding the question? I'll put a non-exhaustive list of some of the questions in abbreviated form and you can provide the actual answer ok?

    1. How do you limit the max RM being produced by your tri given that there are foils in the water which cannot change altitude instantaneously in response to gusts?
    2. How does the boat stay together when the righting moment maximum is exceeded during this situation? You noted that the scantlings for the hull could be reduced because of this limit - does that mean it will fall apart if this situation is encountered?
    3. How is it that the mass of the proposed tri can be so light when all the data points for vessels with less sail, less righting moment, less beam, less complexity in the surrounding size suggest that it will be significantly heavier? Won't all the gadgets and sprockets you propose add to the mass?
    4. How will you stop leeway when the main hull is on foils and only a proportion of the foil will be in the water? (Using 10% of the horizontal foil as leeway resisting hardly seems effective and would only work when the foil is actually pulling down)
    5. How is it that you know the mass of the folding mechanism design but have not yet given any indication as to how it would work or what it looks like?
    6. How are you able to produce planing floats at less than 6kgs when a similarly dimensioned sailboard (ie a planing surface) typically comes in at far greater mass even though it need only support the mass of a single man?


    A simple hand wave saying "I have answered every legitimate issue" doesn't really suffice when you have an opportunity to address the issues right here. It should be no more difficult to copy paste real answers than the excuses that have been flowing for the last couple of pages.
     
  7. Chris Ostlind

    Chris Ostlind Previous Member

    Doug,

    I get the feeling that your "numbers", as they pertain to weights, specifically, have been fudged in order to arrive at a conclusion that suits your expectations... so, help me out here, will ya'?

    Example: You say that the sail for your wonder boat is going to be 130 sq. ft. and that it will weigh a scant 10 pounds... and I quote from your post: "--Sail Area- 130 sq.ft". You go further to state that this sail will weigh 10 pounds... quote: "Sail=10lb." Yet, in the information you just posted regarding the teensy trimarans, the good Italian folks say that their sail, at 86 sq. ft. weighs-in at 8.36 pounds. Looking at the two sails and comparing like for like, I get that the rig on your boat is 1.5 times bigger than the Italian Job. Yet, when we look at your weight figure for your rig, we do not see a 1.5 ratio for the stated weight. You say it's going to be 10 pounds and the ratio so established says it should be more around 12.5 pounds... at least. It could be more, as it's not necessarily clear as to the actual sailcloth weights and needed reenforcements that might be required for the bigger sail.

    It's the process of these few pounds being overlooked that indicate that there's something fishy going on with your crack numbers team and their possible need to get the package down to a certain figure to meet other goals as intended.

    Hey, I'm no engineer, but I can quickly see why Munter would have his eyebrows raised over just about everything you have said about this craft of yours. When the weight for the sail alone is factored to be lighter, then I'm kinda curious as to where you get the values for all the rest of the stuff being shown here. Munter's question about the yet-to-be-seen folding system is right on target in this regard. The 20% error on the sail weight is more than a big deal. Perhaps another handy relational formula should be created that represents the illusive fudge factor we seem to be seeing? ;-)

    I guess that this penchant for lots of numbers as the only real, viable descriptive form is kind of a double edged sword, no?
     
  8. Paul B

    Paul B Previous Member

    You guys don't get it.

    It WILL BE because the Lord says it is so.
     
  9. Alex.A
    Joined: Feb 2010
    Posts: 348
    Likes: 9, Points: 0, Legacy Rep: 108
    Location: South Africa

    Alex.A Senior Member

    I am NOT a foiler-fan and will never sail one - and doubt they will ever be mainstream.... but if no-one had thought to use them, we wouldn't have funky moths or huge speed records etc.
    Give Doug a break :p
    I even had a really stupid idea - a small foiling proa/ tacking outrigger - picture it!!!:eek: But then it is almost a tri.....
     
  10. Munter
    Joined: Jul 2007
    Posts: 285
    Likes: 11, Points: 18, Legacy Rep: 125
    Location: Australia

    Munter Amateur

    Alex - I'm not anti-foiler either and foiling isn't on trial here. Yes, I've raised a few issues relating to the foils but I certainly don't have any aversion to their use. Foiling really is a step change technology, the likes of which doesn't come along often in sailing. I'm all for people experimenting with the technology to see which configurations work and which ones don't. Stupid ideas are fine if you learn from them and move forward. I'd happily see them on more boats if the various technical problems and issues they come with are resolved.

    What Doug is being pinged for is making unsubstantiated claims over his proposed design. He asserts that his numbers are robust and sound. He presents his information in a manner that leads the reader to believe there is sound engineering behind them when in actual fact there is very little. It is readily apparent that they don't stack up and I find it innappropriate that so many claims about performance, comfort and speed and being made when there are so many areas that appear to have flaws. I don't think this sort of behaviour deserves a break so I keep raising the questions.
     
  11. Chris Ostlind

    Chris Ostlind Previous Member

    It would seem that the only boats to be actively using foil assist in a fashion that might be called recreational, are the Stealth and the Nacra 20.

    Alex... The whole thing with foils has been going on since way back in 1906. http://www.hydrofoil.org/history.html The technology is not new, I would suggest that it is not revolutionary and it has as many problems associated as it has benefits. In spite of those truths, I enjoy foiling boats for many reasons.

    Doug has flat-out told us that, "... the detail (accurate data) is required to understand the concept and to explore its feasibility." One can only wonder, then, as to the feasibility of the concept, if the data is not accurate.
     
  12. Alex.A
    Joined: Feb 2010
    Posts: 348
    Likes: 9, Points: 0, Legacy Rep: 108
    Location: South Africa

    Alex.A Senior Member

    Yeah - ok i do get that - but..... you guys also have a lot of experience - you could be positive - and maybe even help come up with some solutions?
    I've noticed a negative trend of "doug bashing" and also said something stupid myself - then thought about it and realized how negative that is.... so turn it around - show how clever you guys re by showing it can be done instead of always pointing out why it can't?:p :D :p :D :p :D :p :?:
     
  13. Chris Ostlind

    Chris Ostlind Previous Member


    Running at my own pace, Douglas. I have interests beyond this Forum.

    You have accurate details?... That could be true if you were to prove the source of your accumulated data. The simple comparison and discrepancy with the little Italian trimaran sail weight and your boat's claimed sail weight is enough to keep me from bothering to look any further.
     
  14. Chris Ostlind

    Chris Ostlind Previous Member


    While I love your enthusiasm, Alex, it may be helpful to fully digest the persona/process you wish to mildly defend.

    Doug brought his "idea" here on his own. Nobody forced him to do so. He must feel compelled to do so, or some other motivating factor is in play... who knows, really? During my time in design school, it was always incumbent upon the person doing the proposing to make his case clear and to have the means to argue his position should it be challenged. It is not the obligation of the reviewers to rescue a design that has been poorly conceptualized. Besides, perhaps you can name the point in time in this thread when Doug actually asked for help in the matter and showed that he was open to external suggestions?

    Doug has proposed a craft for which there is no precedent. Sure, that’s fairly bold, but it carries with it some specific obligations. He seeks to convince the Forum members here that the boat is viable, that his calculations and estimations regarding the capabilities of same are sound and that it would hold up as a functional boat. His numbers are suspect and that has been pointed out respectfully, numerous times. He has done nothing to counter those arguments save to say, "It's true, because I said it was true" and to avoid the difficult questions and observations.

    As a counter to that type of “never been done before” position, I very briefly suggested a different type of boat to fit this indicated genre and showed a couple of renderings to whet the appetite, as it were. The boat I am showing has more to do with an interesting, solution oriented design process that takes the genre in a new direction on many levels, albeit incrementally. It is devoid of hyper-technical and complicated components and is easily buildable by a minimally experienced, boat building beginner in his home workshop.

    The new design is also a boat that has technological idioms that are well understood in the field of trimaran sailing. There are thousands of examples of boats similar to the one I suggest and I do not have to argue the efficacy of the type as a result. Doug could have chosen that path, but for some reason, finds it more interesting to pursue that which does not exist. As a result, he needs to show us more than inaccurate numerical values and when challenged, he needs to justify his reasons for arriving at such values… or he can simply walk away and leave it be until another time when he has things more carefully drawn.

    He has done none of these things and that's where the argument falls apart on this new idea. Since there's no working example, it shall remain unresolved by casual peer review. Again... this is not bashing. It is the crucible of science at work, weeding-out that which does not hold-up to scrutiny.
     

  15. Chris Ostlind

    Chris Ostlind Previous Member

    Apparently amended from Doug's first post on the subject... I'll comment on the new vessels mentioned. Subjects with no comment have already been addressed in a previous post.

     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.