I need some Freeship help

Discussion in 'Software' started by Red Dwarf, Aug 22, 2012.

  1. Red Dwarf
    Joined: Jun 2012
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    Location: USA California

    Red Dwarf Senior Member

    I am working on a canoe stern design in Freeship. I have 2 issues.

    First what does the error "There is no submersion 0.000, 0.914, 2.233" mean. I have looked at the point in the x,y,z mentioned and see no issue? What should I look for?

    Second how the heck do I model a CS hull corrrectly. I have attached my model and a picture of a CS hull. I need to chop off the area below the flat, where the prop will mount.
     

    Attached Files:

  2. philSweet
    Joined: May 2008
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    philSweet Senior Member

    First, add a transom face. Add a point on the centerline at sheer, then add a face, then run model check in tools to make sure the orientation is proper and all your leak points are well above the WL.

    The simplest way to deal with the keel is to add some points in the CL edge using Edge>edge split a couple times and then push the points around. You will want to go back and square up your grid once things are close. Often, you need to add faces and the easiest way is often just to delete a face and then extrude a sample ribbon into that space with all the bends then extrude that perpendicularly to fill the space and then graft it to the rest of the hull with the face command. Download the manual, print it out, and read it. It's worth reading the wiki on the surfacing technique used by freeship.

    It would also help to know what version you are using. Mine is ancient. There have been some forks in the road the last few years.
     

    Attached Files:

  3. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    I am a simple soul ..I design it in Carene about 5 min then export to freeship and bend it to what I want eg extra plank gets bent over to become the deck......for a canoe and simple boats up to about 16 ft I find this works great .
     
  4. lewisboats
    Joined: Oct 2002
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    Location: Iowa

    lewisboats Obsessed Member

    An alternative to add a transom is to highlight the side and bottom lines at the transom and extrude the edges in a negative direction. Set the new points to 0 and your hull is now enclosed. As to the bottom... Split the centerline edge with a point near where you want it, make the point a corner and pull it to the correct position, make any other points corners as necessary and you should come out with what you are looking for.
     
  5. Red Dwarf
    Joined: Jun 2012
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    Location: USA California

    Red Dwarf Senior Member

    Thank you for the tips. Closing the transom fixed the error. I am still trying to model the hull using your hints. I am using version 2.6.
     
  6. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    thought i could give you my model to resize or do with as you wish, but i forgot it was done in a different program, not freeship...


    [​IMG]
     

  7. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    from your first rendering, split the fin on the bottom so it has another point where you want the prop to be longitudinally. Then drag that point upto the level of the flat part of the stern, and check the box "corner". You will have to make another point again, and drag it down to where you want the bottom of the fin, and again check the box "corner".

    Failing that, draw the hull to the aft most point of the fin. Then extrude the flat part of the hull aft to form the flat section, then close the transom.

    Ive done some CFD modelling of these types of catamaran hulls. They are not very efficient, despite all the hoo haa , malcolm tennant name dropping, best thing since sliced bread comments floating around. The best thing about this design is it allows good propellor angle and flow, with easy and convenient engine and driveline installation, great news for engine/prop efficiency. The bad side to this design, is high wetted surface area and thus higher friction/viscous drag. The most efficient form of the CS hull needs to be a rather deep narrow hull, so more draft is a consideration, with limited accomodation space low in the hull. All things considered, there are more efficient hulls than the CS hull, which also allow more accommodation space inside.
     
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