Free Vessel PLANS

Discussion in 'Boat Design' started by Barbaros, Jan 26, 2008.

  1. Guillermo
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    Guillermo Ingeniero Naval

    Eric,
    In my opinion that propeller is going to still have free surface over it and be too close to it, as draught (draft) will not be even 1m (23 tonnes is too much for a 12 m boat). A clearance of 10% diameter over the top tip could be enough. When I mean tunneling, I mean a semi-tunnel conformed by the hull.

    Before going any further, I think it would be interesting to first refine the lay out, perform a detailed lightship weights analysis, a load conditions study, what the trimmings would be, a basic parametric study, etc, etc. I think it is still too soon in the design stage to go full speed ahead with the developing and drawing of a detailed structure. I think you need first to turn a couple of more turns around the designing spiral, otherwise the design may be very nicely draw and displayed but present important design flaws. Don't you agree?

    Cheers.
     
  2. Barbaros
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    Barbaros Junior Member

    Aft lowered & semi-duct propeller

    Hello Guillermo,

    Please find attached, few pictures approaching what you suggest in this forum.

    There is no trim at all aftward.
    It is a good idea to let the hull to sink a little on the aft.
    The propeller will have more water around and at the "top" in particular.

    8.1.jpg
    8.2.jpg
    8.3.jpg
    8.4.jpg
    8.5.jpg
    8.6.jpg
    8.7.jpg

    The profil is lowered in the and a semi tunnel added on top of the propeller.
    Now, this is ready for a second series of plans.

    Regards
    Eric.
     
  3. Guillermo
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    Guillermo Ingeniero Naval

    If you're going to keep that stern, I'd bring the propeller and rudder forwards, eliminating that semitunnel you draw.
    I think it's inconvenient to have the rudder strut extending under the keel, because it can be damaged more easily when grounding, be it accidentally or deliberately. I'd keep it straight with the bottom of the keel or even bringing it upwards the necessary degrees to keep it level, if the boat trims by the stern.
    If there is not enough room for a conventional 3 or 4 blades propeller, you could try a 5 blades, less diameter one. Or then mount another kind of propulsion, such as tractor jets or epicicloidal whale-tale propulsors (this last very adequate for canal navigation). That, again, would need a redesigning of the stern.
    Cheers

    P.S. Visit also: http://books.nap.edu/openbook.php?record_id=5870&page=955
     
  4. Guillermo
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    Guillermo Ingeniero Naval

    On the other hand, if the limiting draught is 1.4 m, you could rake (incline) the whole keel downwards 40 cm or the like (as well as the engine-shaft), making more room for the prop.
    Cheers.
     
  5. timothy22
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    timothy22 Junior Member

    One possible solution to the propeller problem

    may be the Seabright skiff hullform used by William and John Atkin to mount a large propeller on a shallow draft boat. It is essentially a hollow keel and skeg that allows reverse deadrise in the aft sections. See http://www.atkinboatplans.com/ for some examples, particularly the River Belle 35 foot river cruiser.
     
  6. Barbaros
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    Barbaros Junior Member

    Hello Guillermo and Timothy,

    I think trimming the boat by stern and a little work to install the engine with
    the shaft using some slope should sink the propeller enough for better efficiency.

    It will be very helpfull to rework and redesign the basic curves until they
    become satisfactory.
    Guillermo you are right, the design process is a spiral around some hydrostatics.
    The displacement is 15tons for 80cm of draft.
    This is quite correct for 13m steel hull.
    But, I think the final weight will be 18tons with even a better position for
    the propeller.
    The shroud on top of propeller is now removed.
    The work continue ....

    Guillermo, many thanks for your advice.
    Best regards from Paris.
    Eric
     
  7. Barbaros
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    Barbaros Junior Member

    Free Vessel PLANS (Sister ship LUXEMOTOR)

    Now a shipyard in France is building the sister ship of "Free PLANS".
    The hull is longer offering more space.
    img14.jpg
    More virtual pictures showing the construction phases are coming soon.
     
  8. Guillermo
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    Guillermo Ingeniero Naval

    Congs, Eric!
    I have to say with some envy :) that I would like to be able to use Rhino as you do. But unluckily I'm clumsy whith that kind of programs and I do not have enough time to learn now. That's why I need some other people to do that kind of works for me.
    Cheers.
     
  9. FAST FRED
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    FAST FRED Senior Member

    The only problem I have with the first design is the bow seems so high that standing in the Pilot House the water forward would only be visible near the horizon!

    FF
     
  10. Barbaros
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    Barbaros Junior Member

    Front View

    Hi Fred,
    You are right, I have to send also the front view from the helm position.
    I think it is quite good. But, please, give me your opinion, of course.
    This could be improved by lovering the bulwark near the bow.
    img16.jpg
    The 2nd picture is the profil view which say's that anything above 70cm at
    21m distance remains visible.
    While I was sailing in French Canals with different style boats, I was always looking away from the bow.
    But again, it could be improved.

    This is about the 2nd Luxemotor design.
    Next time I will reproduce the same pictures for the 1st design.

    img17.jpg
    Regards
    Eric.
     
  11. Barbaros
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    Barbaros Junior Member

    Hello Guillermo,

    I have some spare time and if I can help you somehow please let me know.
    As you can notice even if I can use quite well Rhino, I need a Naval Architect.
    This should be what the people usually call "complementarity".

    Kind regards.
    Eric.
     
  12. Barbaros
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    Barbaros Junior Member

    Front end visibility

    Fred,

    Please find below two pictures showing the front visibility of Free Vessel PLANS.
    9.1.jpg

    As you can notice the bow height is not modified.
    But, this is an open subject (it could be lovered without problem).
    I agree with you, this is an important subject in Canals.

    9.2.jpg

    The pictures which you see is the work under progress as recommended by
    Guillermo. But it is not finished yet.

    Regards
    Eric
     
  13. Guillermo
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    Guillermo Ingeniero Naval

    Hi Eric.
    Perhaps we can collaborate in the future. We'll discuss it when the adequate job arises.
    Regarding visibility from the bridge forwards, take into account that trimming by the stern reduces it.
    Cheers.
     
  14. Barbaros
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    Barbaros Junior Member

    One Hull two different Vessels

    Hello Guillermo,

    With some minor modifications, same hull (bottom and chine) could be used for two totally different Vessels.

    The 1st one should be OK for Sheltered Water navigation and perhaps some
    coastal Navigation also.

    10.2.jpg

    The 2nd one seems to be a little ambitious.
    But there is much more space for habitation for exactly same dimension.

    10.1.jpg

    While I continue to work on 1st one, could you please give me your comments on 2nd Vessel.

    Regards.
    Eric.
     

  15. Guillermo
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    Guillermo Ingeniero Naval

    My dear Eric,
    Please don't get offended, but I cannot go on with advising you through a full design process through these posts. I strongly recommend you to hire the services of a NA before proceeding any further with your designs, be it me or any other colleague.
    All the best.
     
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