Empirical Formulas for Catmaran passenger ship

Discussion in 'Boat Design' started by Tasnel Tayyar, May 4, 2020.

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  1. Tasnel Tayyar
    Joined: May 2020
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    Tasnel Tayyar Junior Member

    Hello there,
    I am studying Naval Architecture and Marine Engineering, for this term I need to design a catamaran passenger ship but I couldn't find any empirical formulas for calculating main dimensions.

    Is there any source you can recommend for me?
     
  2. DCockey
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    DCockey Senior Member

    Start by searching for vessels similar to what you are designing.
     
  3. bajansailor
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    bajansailor Marine Surveyor

    Welcome to the Forum Tasnel.
    As David mentions above, just have a look for other passenger catamarans on the internet that are similar to your Statement of Requirements.
    You don't need 'empirical formulas' - sister ships already built are a much better source of information.
    Maybe you could tell us a bit more about your SOR?
    How many passengers, what speed is required, what is the route and what is the range required?
     
  4. oldmulti
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    oldmulti Senior Member

  5. Tasnel Tayyar
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    Tasnel Tayyar Junior Member

    Thanks for your warm welcome firstly :), I looked for many sample ships and I found some main ratios like L/B B/T, etc. but I was not sure that it works because my other friends are using some formulas for their bulk carrier desings.
    My requirements are 400 passenger capacity and 32-knot speed, she will work between Istanbul and Bursa it is about 50 miles.
     
  6. TANSL
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    TANSL Senior Member

    Do not search for magic formulas, or similar, because they do not exist.
    The first thing you should do is a much more detailed SOR. For example, carrying 400 passengers on one deck is not the same as carrying them on two decks. Do you need a seat for all of them ?, there will be a bar service, drinks, etc?, Autonomy ?, design category ?, what regulations should be applied to the ship ?, materials to build it ?, limitation in dimensions for any reason? ...
    Once that is defined, make a General Arrangement plan to check that there is space to carry everything you want, see if there are catamarans similar to yours and, after all, of course, if you want, ask again in this forum.
     
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  7. Tasnel Tayyar
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    Tasnel Tayyar Junior Member

    Alright then, thank you very much for all your answers
     
  8. bajansailor
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    bajansailor Marine Surveyor

    Tasnel, have a look through the archive on the Baird Maritime / Workboat World site - lots of nice articles about catamaran ferries are available here for reference.

    Work Boat World Vessel Reviews Archives - Baird Maritime https://www.bairdmaritime.com/work-boat-world/work-boat-world-reviews/
    And
    Passenger Vessel World Archives - Baird Maritime https://www.bairdmaritime.com/work-boat-world/passenger-vessel-world/
    Also their Facebook site -
    Work Boat World - Baird Maritime https://www.facebook.com/workboatworld/

    Incat Crowther are world leaders in large fast catamaran ferry design -
    Tourist vessels designed by Incat Crowther http://www.incatcrowther.com/products-tourist
    And
    Incat Crowther – Commuter http://www.incatcrowther.com/products-commuter

    Also BMT Nigel Gee -
    Projects https://www.bmt.org/projects/#Markets/1062

    Lots of amazing ferries for reference in the links above..
     
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  9. Ad Hoc
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    Ad Hoc Naval Architect

    There are more of these types than I can shake a stick at!!
    You will have no problems identifying similar types of catamarans.

    But a vessel of this nature is driven by the required deck area... the amount of area you need to sit 400 pax.

    Thus just search any of the weblinks given by Bajansailor and you'll quickly find common ratios.
     
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  10. gonzo
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    gonzo Senior Member

    I don't know what regulations apply for your area, but usually there is some formula of deck space per person, with a number for standing and one for seated.
     
  11. TANSL
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    TANSL Senior Member

    It would be very interesting to know some of those formulas.
    .. and, on fast ferries, all passengers are required to have a seat.
     
    Last edited: May 5, 2020
  12. bajansailor
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    bajansailor Marine Surveyor

    There are SO many fast catamaran ferries out there that are capable of a service speed of 32 knots while carrying 400 passengers - Tasnel should be able to come up with some empirical data of his own if he compiles a spreadsheet of essential particulars re these vessels?
    All (or most) of the information required should be available on line, on the websites of the fast ferry builders and designers?
     
  13. Tasnel Tayyar
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    Tasnel Tayyar Junior Member

    Wow
    Oh thank you very much again i am looking them now :)
     
  14. Tasnel Tayyar
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    Tasnel Tayyar Junior Member

    I also saw some formulas and actually that was the reason I wanted to ask for whole empirical formulas to this site. To illustrate this formula used for calculating waterline length:
    1.15 x L x B = passenger capacity x 0.75 but there was no reference for this formula
     

  15. TANSL
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    TANSL Senior Member

    L/B or B/T ratios, etc., which are intended to ensure certain stability or load capacity in the first moments of design, in a catamaran have no reason to exist. Stability is assured and catamarans are not usually boats with large differences between light ship and full load weight. So I tell you that these formulas do not exist, the designer has many more options. It is very important that there is enough space to house the entire passage and all the services associated with it (do not forget the facilities for the disabled, width of corridors, toilets, doors and access ramps). For more aesthetic or tourist than functional reasons, it may be desirable to carry the passage in one or two decks. Therefore, the first thing is to do a GA drawing because everything else, displacement, stability, ... with a catamaran, can be arranged.
     
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