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

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

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    I don't think Ad Hoc missed a calling in the Diplomatic Service, what is "irascible" in Spanish ? Maybe you are getting the blame for the Spanish Armada ? :D However, I'm not so sure spoon-feeding answers to students is strictly in the spirit of learning, after all, the idea is to become independently competent in your craft, not have someone else do it for you.
     
  2. TANSL
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    TANSL Senior Member

    The "Spanish Armada" which Spain went against England, sank off the coast of that country due to bad weather. There is therefore no reason for Ad Hoc hate me for that. Much of the wealth that England had at that time was because the English pirates ransacked Spanish galleons which, loaded with gold, came from America (which we were fleeced). Nor, therefore, would that cause for hatred. So what?:confused:
    As for the OP, we are used to see many students using this forum to solve problems easily and comfortably. It would be more correct to express their doubts to his teacher but I do not know why, they don't. I thought that, perhaps, to question certain things on the brief and discuss them with the teacher could have some educational value. Some say that's nonsense.:p
    By the way :
    irascible (english) = irascible (spanish)
    prepotent (english) = prepotente (spanish)
    deified = endiosado
    fatuous = fátuo
    pedantic = pedante
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

    Correct on both counts.

    For example:-

    A students’ question:

    A rectangular vessel is 15m wide and 10m deep and has deck plating of 5mm thick and its sides and bottom are 9mm thick. It is subjected to a bending moment of 65MNm and shearing force of 3.15MN, according to classical beam theory calculate the max tensile and compressive stress.

    Tanls reply:

    Rectangular, that’s rubbish. Boats are not rectangular. …what would make someone want a rectangular vessel, please tell me why? Deck plating of 5mm, why 5mm….should it not be 6mm as per other vessels and why are the sides and bottom thickness the same…seriously why on earth are they made the same, it doesn’t make any sense to do that it is not efficient. Please tell me why they are the same.

    Students’ reply:

    1) Elect to answer the question given using the data provided,
    or
    2) Query the question endlessly showing a lack of understanding of what is being asked and hence how to actually calculate and answer the question at hand!

    Anything other than no.1 is nonsense.
     
  4. TANSL
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    TANSL Senior Member

    Another lecture, given by an intellectual. Thanks, Ad Hoc.
    Good example, it is good to have these distractions, jokes, among serious discussions. It allows us to relax. You make my life happier, Ad Hoc. Thanks again.:D
     
  5. Devu De Goa
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    Devu De Goa Junior Member

    Thank you for the document Sir. I enjoyed reading the other replies, but will reply when I have some more time.

    LOL about machiavellian. :D But precisely that is a challenge area and a good topic for further research. Will explore more on this as we discuss further.

    Thank you everyone Sirs.
     
  6. jarmo.hakkinen
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    jarmo.hakkinen Junior Member

    Some papers

    I've spent some time in the wonderful world of the internet, searching for the online information about designing of boats and marine craft in general. Here's a link to my Drive account, where there are some papers (some 30 of them) about semi-planing ships, predicting their behavior in terms of resistance, seakeeping, stability (also dynamic), trim, squat etc.... Have a look, you might find them interesting to read and study, to make more relevant and more accurate educated guesses (that's called design) on your project. You might like to study for instance the NOVA-series, if shallow-water application is of concern. https://drive.google.com/open?id=0Bw3Uk0r4KE0JZk0tTkdZVkVDbms
     
  7. Devu De Goa
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    Devu De Goa Junior Member

    Wow! Thank you very much Sir. It's wealth of information. Thank you so much.
     
  8. Devu De Goa
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    Devu De Goa Junior Member

    :D Thank you for you wishes Sir. I managed to submit a preliminary GA. Kindly find it attached. But there are some comments of the Professor, so will have to revise and resubmit. Will update when that is ready.

    Kindly provide your comments on this one so that I can add to my revision. :)
     

    Attached Files:

    Last edited: Oct 31, 2016
  9. waikikin
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    waikikin Senior Member

    Hi Devu,
    I'd offer the following though not really my field..
    -push forefoot forward.
    -raise freeboard forward
    -square off the bow for pushing on/boarding
    -illustrate fairleads and bitts with safe working clearances
    -better/sheltered access to machinery space
    -access wc & wash facilities from wheelhouse/deck level
    -offset helm stb and raise above passenger seating for sightlines
    -reverse forward screen rake

    Some stuff not clear on my machine like tank details, your power & speed stuff I have little idea.

    Jeff.
     
  10. TANSL
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    TANSL Senior Member

    In addition to the good points from waikikin, risking someone tries to show how ignorant I am, signaling the stupidities I say, I would add the following views:
    • Place the rudder and engines, most aft.
    • Place the emergency group.
    • In the engine room seems to be enough place to put fuel tanks within this space. This would probably help to reduce the height of the double bottom.
    • Try, according to the above, the floor of the cabin superstructure is level with the main deck. The height of the space below the main deck would be small but this is normal in boats, small length.
    • Place the air intakes and exhaust of engine room at the rear of the superstructure, at side, to try to have the aft deck as clear as possible.
    • Hatch assembly/disassembly of machinery on main deck.
    • Access to the forward store could also be performed by a door in its aft bulkhead.
    • Make flush watertight access to the steering gear compartment.
    • The crew area, under deck, needs a secondary/emergency exit.
    • Missing bollards and other deck equipment.
    • Considerate the opening of the main deck to ensure its structural integrity and tightness.
    • The stairs down to the local crew, probably, needs to have coaming with sealing possibility.
    • In these boats it may be that passengers need access by the bow. Leave a hole in the bow railing.
    • It takes a tank for gray water.
    • Elements of rescue and fire-fight throughout the ship and on deck.
    • The relative position of the winch and the anchor pocket does not seem right.
     
  11. Devu De Goa
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    Devu De Goa Junior Member

    Sir, coincidentally, I got similar comments to what you have mentioned above from my Professor. Already revised the GA today before I could see your comments, but I guess most of what you wanted is done. Still I will recheck the GA with your comments again.

    Kindly find attached the revised GA. :)
     

    Attached Files:

  12. TANSL
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    TANSL Senior Member

    Later I'll take a look at your new GA. You note that my comments do not have to be the truth. I can only express my opinion based on the design of some ships of this type that I've done. But there are many other circumstances that may influence your project and I do not know.
    Greetings.
     
  13. Rabah
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    Rabah Senior Member

    Hi Devu De Goa,
    There can be this model it is pleasant to you. It was made by me with training aim. The sizes:
    Loa=17,576m; Boa=5,964m, Hmax=2,46m
    At-sea with draft=1,2m it is received displacement=51,848t
    Calculation on Orca3D is the following:
    At VCG=1,4m the hull will float in a semi displacement regime as Fnv <3
    At velocity 20kt total power=2 x 900kW; Fnv=1,7; dynamic trim=7,19deg
    At velocity 25kt total power=2 x 1100kW; Fnv=2,137; dynamic trim=7,42deg
    That now to you is necessary to make it is to scale the model up to those sizes which are necessary to you also with approval of the professor.It will help you only provided that you yet have not accepted final award for the geometric shape of the body line of the hull! I wish you good luck.
    I help because I remember my student's years. I hope that when you will be on my years, you will help too to young students.
    __________________________
    NA Razmik Baharyan
     

    Attached Files:

  14. Rabah
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    Rabah Senior Member

    Hi Devu De Goa,
    Friend from Norway - NA Alexander Aleksanov, has given me idea to make the transom from curvilinear surface and has shown as it to make on Shape Maker saving thus outlines of all remaining surfaces. The idea was pleasant - see realization on Rhino. Except for that I was a little bit pick up the bow, so that now the sizes are the following:
    Loa = 17,392m
    Boa =5,964m
    Depth max =2,6m
    At draft = 1,2m in sea Displacement = 47,39t; LCB=6,349m; VCB=0,781; Cb=0,493; Cwp=0,808; Cx=0,702
    Advisory - the vessel should be projected so that LCG=LCB=6,35m, certainly if these ship dimensions will be saved.
    _______________________
    NA Razmik Baharyan
     

    Attached Files:


  15. nzboy
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    nzboy Senior Member

    Im glad this is just a model and not a production boat. 51 tons for this size boat is a lead sinker . 1.2 total draft maybe acceptable but not hull draft
     
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