Uni Ship Design Project Help Needed

Discussion in 'Boat Design' started by Rian199, Sep 29, 2015.

  1. Rian199
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    Rian199 Junior Member

    Hi, I am new here on this forum. I am a second year Naval Architecture student in Australia. For our final project, we are to do a concept design for a passenger ferry, adhering to a given design brief which I have attached. Note, it is the passenger ferry, not the patrol boat. I have a semester break and will be working on it this week, but I am feeling a little stuck on the hull design since there are so many possibilities. Though our lecturer suggested we stick with monohull, which narrows it down a little. But I would like to get some more advice on the specific design etc. I have started on a workboat example hull in MaxSurf, and gave it a hard chine, and modified the dimensions to suit my specifications, and our lecturer also gave us one of her examples to look at. I aim to use water jets for propulsion, and I know I still have to allow for that at the stern section, so I will still design that. I have attached both the designs as well, so if someone can please have a look at the brief, and the designs and maybe give me some tips/advise on how to proceed, and any design additions/changes that would be beneficial for the design specs, that would be very much appreciated :)
     

    Attached Files:

  2. fredrosse
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    fredrosse USACE Steam

    Water Jets?

    Just curious, why water jets? I am under the impression that this type of propulsion would be inefficient compared to open propellers, what might be the conditions that would justify water jets here?
     
  3. Rian199
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    Rian199 Junior Member

    It's just what is in the design brief, though, having said that, our lecturer said that she would be lenient on some of the specs, given we could give good reasoning why made the changes
     
  4. NavalSArtichoke
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    NavalSArtichoke Senior Member

    Several years ago, I was involved on a similar project where the owner built an aluminum crewboat approx. 65 m long which was powered by water jets.

    This boat was intended to operate in West Africa, where there aren't many prop shops. Using water jets also cuts down on draft requirements for these vessels, since there's no shafting sticking below the hull. The jets also provide steering, hence no rudders are down there either. Without all that stuff sticking down, hull resistance is reduced.

    Operating at speed most of the time is an important consideration, too. There's no cavitation to worry about with a jet, and the jets are about as efficient as props at typical boat speeds.

    http://www.hamiltonjet.com/global/waterjet-overview
     
  5. Rian199
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    Rian199 Junior Member

    Actually just as I was going through my notes, I came across a section where my lecturer said pretty much exactly what you just said, without the cavitation remark, which is actually a really good point that I haven't considered before.
     
  6. Ad Hoc
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    Ad Hoc Naval Architect

    Rian199

    I wouldn't worry/focus too much on the exact hull form shape. All you need, from your hull, is a set of hydrostatics. Since you will need to do the following first:

    1) Draw a GA....search the interweb for similar size vessels. See how they are arranged, and then draw a similar one to your own design and that follows the profile shape of a hull, any hull.

    2) Do a weight estimate. I realise this is not so easy first time. But you should start to learn the standard group format:
    Group 1 = Structure
    Group 2 = Machinery
    Group 3 = Electrics
    Group 4 = Comms/control
    Group 5 = Aux Machinery
    Group 6 = Outfit
    Group 7 = Armaments
    Group 8 = Fluids in systems

    Then add your payload.

    Doing your first weights will be a challenge, but try to get as much eqpt weight as possible. For the structure, just take the surface area, assume a constant thickness of say 6mm all over, that's your plate weight and double it for internal frames, then add foir misc items = group 1...do this for all the other groups in a similar fashion.

    Then once you have that, what is the weight and does it match the hydrostatics at the design draft..and more importantly..the LCB and LCG??..if not redesign/draw to match the two together.

    That is the hardest part and shall take you the most amount of time. Once you done that, you can look at the rest as it is easier.

    Good luck.
     
  7. Rian199
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    Rian199 Junior Member

    Thanks Ad Hoc

    Thanks the advice, that does make sense. We have done sample weight estimates, and I have set up an spreadsheet for that, and we covered General Arrangements as well. So what you are saying, the best way to do this is doing those first and then the final hull shape to fit the calculated characteristics (ie. LCB, LCG etc.)? Would I do that using the parametric transformation function in MaxSurf, and then just adjusting the coefficients to get the desired speeds etc.? Or?
     
  8. Ad Hoc
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    Ad Hoc Naval Architect

    Correct..that's how you do it, not the other way around. Since the "design" is the SOR = Statement of Requirements. Your SOR is the list you attached in post #1. So you must design your vessel to satisfy that SOR.

    What you often find is that once you have done this once.... the design spiral...you find that may be the weight is too much or you can't find enough room for all the pax etc etc...then..well, that's where one begins being creative :)

    Nope, yuor first task is to match the design/weights/GA to a hull form you have. If you find you can't, as noted above..what can you change so it does match? If you find after many attempts you can't match it, then yes, you need to select another hull, if you have one, or, simply modify the existing one you have to match the DESIGN parameters you have created.
     
  9. Rian199
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    Rian199 Junior Member

    Also what software is best to do the GA? thanks again
     
  10. Rian199
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    Rian199 Junior Member

    Okay, got you. We have actually done the design spiral during one of the weeks, and I'm a little stupid for not referring to that.. Guess I just saw the project as a whole and didn't start by breaking it down,so it just looked a little intimidating.. Okay so I will follow it that way and try and work those out in the next few days and see how I go. Again, just in case you might have missed that post, what software is good for the GA? We have discussed and learnt about GA's but I haven't done one before
     
  11. Ad Hoc
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    Ad Hoc Naval Architect

    Don't get stressed about that. There are more software packages out there than I can shake a stick at! It is the least of your worries. Just use any CAD that you know how to use or have easy access to. Since a picture is a picture, no matter what electronic bits n bytes are used in the process! So long as the end results looks like a GA...it matters not.
     
  12. Rian199
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    Rian199 Junior Member

    Ok, well I would have to brush up on MicroStation then, because I've got a student version of that. While reviewing our study on General Arrangements I found this ferry design online:

    http://mwdesign.net.au/30m-mono/30m-decks.htm

    Please correct me if I am wrong, but I figured it is pretty close to my requirements, and by tweaking the capacity, beam and propulsion, it could satisfy what I need. Since I only need a 120 pax ferry, I thought if I decreased the beam by eliminating the two rows of chairs on either side, I could get lower resistance, and by increasing the propulsion power I could possibly achieve the desired service speed. Of course I know it's not that simple and I would need to check the new stability data, weight estimates, Fr etc. after the modifications. I just made these assumptions intuitively. Though I do see that I need 10 times the amount of fresh water capacity of this design according to my SOR, but (again correct me if I'm wrong) by crude calculations and assumptions, I would need a lot less capacity for fuel, since I am refueling daily after 4 trips (120NM in total)?

    I will try not to hassle you with too many questions because I already appreciate the effort to answer my questions out of your own free will. So thanks
     
  13. cnnammu
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    cnnammu New Member

    Hi,Rian 199

    If you have rough hull form, you should check your hull form whether it is satisfied whether or not , your required speed and preliminary stability.As you are using maxsurf, you can do it with maxsurf stability & resistance module. Using that softwares, you can make more easier and quickly for your design spiral.
     
  14. fredrosse
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    fredrosse USACE Steam

    Jet Drive

    I understand the several advantages of Jet Drive, but if they were the right choice for a passenger ferry you would see them in fast passenger ferry service. I think they are a rare arrangement in ferry service, and there are logical reasons for this, generally cost based.

    Literature from Jet Drive companies will always be biased toward favoring jet drives, while realistic evaluation will often show them to be very expensive compared to conventional drive. Don't fall for all the glorious statements about jet drives on a jet drive manufacturer's website.

    High speeds tend to close the gap between propellers and jets, but at the stated speed requirements for your project I think you will find the propeller(s) are most valuable. This ship will be burning on the order of 300 US Gallons of Diesel fuel per hour, an expense that should have close evaluation considering propulsive efficiency.

    For ferry service, entering ports again and again, the clearance advantage, (as well as several other jet advantages) will often become moot points. As far a cavitation issues, these can be addressed very well with propeller drives.
     

  15. NavalSArtichoke
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    NavalSArtichoke Senior Member

    Well, the US Govt. uses Wartsila jet drives for the JHSV high-speed, shallow draft transports currently being built for the US Army.

    https://en.wikipedia.org/wiki/Spearhead-class_joint_high_speed_vessel

    Hamilton Jet has a rather extensive list of vessels and vessel types which use their jet drives, including a number of fast crewboats, similar to the one I mentioned:

    http://www.hamiltonjet.com/global/applications

    Incat high speed ferries also use Wartsila water jet drives for their Ro-Ro ferries which operate around the world. These vessels are approximately 100 m in length and can carry up to 1000 passengers and 150 cars at speeds of up to 50 knots.

    http://www.ship-technology.com/projects/francisco-high-speed-ferry/

    If these are not a sufficient number of installations, I'm sure I can find more.

    If no one was buying these drives, manufacturers would not be building them.
     
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