19m semi displacement / planing hull "Port service boat"

Discussion in 'Boat Design' started by Devu De Goa, Oct 29, 2016.

  1. Devu De Goa
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    Devu De Goa Junior Member

    Dear Sirs,

    I am currently doing a Masters course in ship design at a University in the European Union. As part of the curriculum we are required to do a vessel design project. I have chosen to design a port service boat of about 19m.

    The attached pictures shows the approx values of Froude numbers for different lengths and speeds. I hope it means that the vessel of this Froude number should be expected to start planing at 23 knots. So it has to perform at semi displacement mode from 20 to 23 knots. This is a challenge for me.

    I am at a stage of choosing a good hull series for this project. I want to make it a good learning experience by considering all options at every stage (as time permits). At the end of this semester, i.e. about 2.5 months from now we will be expected to do model tests for our hulls. So there will be an opportunity to actually verify the results of our discussions here.

    Keeping this in mind I would request the guidance of the senior members in this forum in choosing different parameters for my vessel. To begin with please suggest a good hull series which will give good performance (stability and maneuvering).

    Thank you.
     

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  2. TANSL
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    TANSL Senior Member

    Imo, a "Port service boat" should never reach planing speed, is more,speeds bigger than 4 or 5 knots are prohibited inside the ports.
    Imo, a "Port service boat" should be prepared to take, at some point, very heavy loads so a displacement hull type is more appropriate. They usually have a cabin with seating for no more than 12 passengers, a wide and clear deck and a hydraulic crane, for example, 15 t*m.
     
  3. Devu De Goa
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    Devu De Goa Junior Member

    Thank you Sir, for the reply.
    You are right about the speeds. But this is the requirement given to us by the Professor in the project specification sheet. So can not deviate from that. As a University project sometimes the objectives are different from an actual working project so we will have to take it in that spirit.

    So I will have to focus on the semi displacement + planing range, to choose a hull and ensure that it performs well in both ranges.
     
    Last edited: Oct 29, 2016
  4. TANSL
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    TANSL Senior Member

    I know that a college project may be at the limit of possible but should be possible. In your case the high speed will not allow carry much cargo, which is essentially for a port service boat, unless the vessel, even if that type, need to perform other services that have nothing to do with the normal port services. In that case, you should give us a more complete SOR.
     
  5. Devu De Goa
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    Devu De Goa Junior Member

    Okay. Kindly find attached the spec.
     

    Attached Files:

  6. TANSL
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    TANSL Senior Member

    I'd forget planning speed and to continue with your SOR, I'd think of a boat semi-displacement although I think it would be better a displacement hull.
    Although it is not what you ask, let me make the following comments.
    I do not understand why it is required a length of 18 to 22 m if you plan to carry just 8 passengers.
    Good maneuverability, how fast ?. Usually they need to be very maneuverable at low speeds.
    These boats are frequently hit with the other boats. Do you think correct selection of an aluminum structure?
    A range of 10 hours seems very low for this type of vessel. It is not practical to have to go to refuel every 10 hours when the workday of this boat should be 24 hours a day, 7 days a week
     
  7. mydauphin
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    mydauphin Senior Member

    Kind of reminds of the small supply vessels used for oil rigs.
     
  8. Ad Hoc
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    Ad Hoc Naval Architect

    DDG

    Firstly forget all the nonsense above from Tansl. Your brief is very clear, the reasons for such are irrelevant, except to satisfy them.

    Your first task is to draw up on a sheet of A3 or A4 paper, with scale rule, in pencil a simple layout. The layout of a deckhouse which carries 8 passengers, in seats and then the 4 crew, and then also the small galley and the toilet. Everything you draw to be correct scale.

    After you have drawn this up the space envelope of what type of hull to use becomes clearer. Since either you will or will not have room for a monohull. Then the same with using a catamaran. Each selection has its merits.

    Once you have done that, begin the draw your GA in a bit more detail. Plan and profile view. Again still in pencil but with a scale rule.

    Then you can estimate the size (length) of the engine room, this too adds to the length/choice of hull.

    Once you have done that, select the hull that you prefer to use, perhaps because it is easier to fit the engines in, or perhaps because it offers better stability etc.

    So, now you have a very simple set of lines that can be drawn up, very roughly. From this you can sketch up a midship section. This can be used for your review of Class rules for the structure.

    Now you have enough information to begin a preliminary weight estimate. Once you have the weight estimate you can establish in more detail what size of engine you will need to achieve the required speed, and also which chose of propulsion...jets, or props.

    After all of this, review again...can you still satisfy the brief?..if not change that which needs to be changed and review again.

    Simple :)
     
  9. waikikin
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    waikikin Senior Member

    Get cracking

    Some top advice from AH there above.
    That text is your marking criterion...

    Your GA is due TOMORROW!!!

    All the best from Jeff
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    1000 litres of freshwater capacity eh ? Must be for the Jacuzzi after a hard day's work.
     
  11. waikikin
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    waikikin Senior Member

    Could be to wash the windows after blasting around at 20 all day...
     
  12. TANSL
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    TANSL Senior Member

    Thanks Ad Hoc, you are my idol. I will always be grateful for your lectures.
    I agree with some of your recommendations, not all. I have not tried to change the "brief" indicated by the OP, I simply expressed my opinions, what's your problem with it ?, which of them is nonsense ?.
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    I'd guess the student has only to comply with the brief as laid out, his is not to reason why, his is but to do, or die (wondering why it got a fail).
     
  14. fcfc
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    fcfc Senior Member


  15. TANSL
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    TANSL Senior Member

    Of course, that is so, I agree. But it would not be the first time anyone, without leaving the subject of some thread, not directly answers the question but expresses one opinion. If what I have done is wrong, I apologize. In any case, what thing that I have said is nonsense?. Because, perhaps we all could learn something with that explanation.
     
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