Building of Aluminium Boat . Mounting of hull framing structure

Discussion in 'Boat Design' started by an2reir, Feb 27, 2019.

  1. an2reir
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    an2reir fifty boat designs

    Hi Efficiency thanks for feedback. I think thats allright getting the longitudinals to touch the plating without dramas :) In my opinion to try and mount the entirely welded bottom framing into the hull bottom thats made on a support that is not tight is not right ; is not to be attempted at a first build of the boat. I think the concept of developable surface in the mathematical sense with zero gaussian curvature is one thing and " unrollable" surface in the sense wich is being in daily engineering design office practiced in dozens of companies is a slightly different thing. for example when need to make fast hundreds of "unrollable surface you do not have the time to check their mathematical developability of zero gaussiaon curvature other than by the surface curvature check in Rhino-
    so in practice there may be many folks like me to take
    their unrollability validation for good. I' ve met people who were required to produce such dozens of developable surface and they just had no time to valiadate each and every one with the perfect procedure . In my view a surface check of gaussian curvature with the limits set - 0.000005 mm to 0.000005mm showing light bluish is valitation enough bottom is buildable.
     
    Last edited: Mar 4, 2019
  2. an2reir
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    an2reir fifty boat designs

    Today the builder did weld the framing to the bottom starting from rear towards fwd and the gaps were closing at this hour until and including station 4. ( wich is a very big deal) My builder did take the decision to go this way by himself ; it is not the method I recommended and I did illustrate with the Professional Boatbuilder magazine article . The builders were strating from the rear of the boat pulling the boat bottom upwards with a small crane . It did look quite promising as they did succeed to wels all frames including frame number 4. To be noted that the bottom they are attaching is a bottom made by welding the bottom sides at center on the inside with contihuous wels plus the chines welded on the chine line . They did not learn not too much from the Professional Boatbuilder Magazine article I sent them saturday. It seems more the Divine intervention is indeed here at work.
     

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    Last edited: Mar 6, 2019
  3. TANSL
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    TANSL Senior Member

    Keep in mind, I suppose you already do, that forcing the plates to go to the reinforcements could introduce great internal tensions that, at some point, could give a dislike.
     
  4. an2reir
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    an2reir fifty boat designs


    Hi TANSL yes tensions indeed may very likely have been induced- but then it appears 90 % bottom framing is already welded.
     
  5. DCockey
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    DCockey Senior Member

    For volume production would it be preferable for the plates to be bend easily and quickly into position for welding without needing to pull on them with cranes or similar?
     
  6. an2reir
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    an2reir fifty boat designs

    Hi David, yes of course that would be preferable. Your above drawings of a correct developable surface of zero Gaussian curvature are an excellent illustration of how a boat bottom may be designed 100% correct developable . I did undersand that clearly.
     
  7. Ad Hoc
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    Ad Hoc Naval Architect

    One should never pull or force aluminium plates into place. It is bad shipbuilding practice and leads to a multitude of problems later.
     
  8. an2reir
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    an2reir fifty boat designs

    Hi Ad Hoc, I do totally agree .
     

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  9. an2reir
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    an2reir fifty boat designs



    Hi Ad Hoc, thank you, I did more research in regards the unrollability vs developabilty of aluminium boat bottom. I want to express thanks to the author" for their work - the article " Order of Assembly " in Professional Boatbuilder Magazine issue 151 Oct Nov 2014 - and for the feedback in regards aluminium boat building. I am reading carefully the article in the Professional Boatbuilder Magazine USA. Yesterday I did some further research with Lowell Walmsley from McNeel. Essentially the result is : a. the bottom surface Lowell made is unrolling in a cutting file that is identical to the cutting file of the bottom surface I originally made. My keel and chine curves were considered by Lowell good to create the developable surface on.
    b. As David Cockey has made clear in his posts , Rhino and Paneling Tools do unroll surfaces that are not 100% developable but are "good enough" c. that means I now have one bottom plate cutting file and two sets of bottom framing cutting files - because I just made a new set of cutting files for a new set of bottom frames & stringers to adapt to the more rounded bottom version of the bottom and to potentially to be easier workable by the builder. d. It appears the bottom may have been buildable allright in the first place if the mounting and welding done skillfully . c. I thought of one option for mounting the initial bottom plate ( wich has its sections slightly rounded but on a very large radius - therefore more "tight" to mount ) would be to look at the ruling lines and mark them, and start attaching one bottom plate at the 3/5 towards forwards on the keel and at the chine where ruling line indicates - and move alternatively towards fwd and rear. I am now searching for a text version of the article in the Professional Boatbuilder magazine so I would be able to translate it. I would probably think of fairing the boat bottom with epoxy fairing like was done at the sail boat I did design and was built in South Korea ( attached photo above post)
     
    Last edited: Mar 6, 2019
  10. an2reir
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    an2reir fifty boat designs

    Thank you everybody and I am wishing you a Happy Easter ! Just to let you know : the aluminium boat has been launched and tested and did look good . That seems to indicate success in my endeavor to implement aluminium boat design and production to Danube River Delta - Romania :)
     

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  11. DCockey
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    DCockey Senior Member

    Thanks for the update.
     
  12. an2reir
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    an2reir fifty boat designs

    Happy Easter David ! Happy Easter to all who kindly gave their input and thoughts.
     

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  13. Maxxi
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    Maxxi Junior Member

    Very nice build! Looking to do something similar, but only one piece for private use. Quite suprised how much talk there was before, when there was an issue, but no comments now when the hull is finished and tested on water..? Pretty sure that the issue wouldn't been there in first place if the hull would have been assembled little differently.
     
  14. an2reir
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    an2reir fifty boat designs

    Hi Maxxi happy Easter to everybody ! Thank you for appreciation. Actually I did learn from all those who were kind to write their feedbacks, and I was very glad to read from experts from various continents. In real life the answer to my query came in a different way. Axctually there is a kind of setup for the proper precision fabrication of the aluminum boats - that is not complicated but does require some work. And yes my boat does look brilliant on water at launch day doesnt she :) ?
     

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  15. Maxxi
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    Maxxi Junior Member

    Yes she does indeed :):cool:
     
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