My newly designed catamaran plan

Discussion in 'Boat Design' started by metin_mehel, Aug 5, 2015.

  1. metin_mehel
    Joined: Jul 2009
    Posts: 158
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: turkiye

    metin_mehel mech.eng.

  2. messabout
    Joined: Jan 2006
    Posts: 3,113
    Likes: 279, Points: 83, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    Technically speaking it as Proa not a catamaran.

    I expect that you will want to move the helmsmans station forward to trim the boat to advantage and re-calculate the strength of the beams that link the two hulls.
     
  3. lucdekeyser
    Joined: Aug 2004
    Posts: 152
    Likes: 6, Points: 18, Legacy Rep: 51
    Location: Belgium

    lucdekeyser Senior Member

    You have ways to go to compete with most of these tacking proa's at this price for plans.
     
  4. metin_mehel
    Joined: Jul 2009
    Posts: 158
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: turkiye

    metin_mehel mech.eng.

    My plan is around 100$ how about those you shared?
     
  5. metin_mehel
    Joined: Jul 2009
    Posts: 158
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: turkiye

    metin_mehel mech.eng.

    What is the advantage I did not understand clearly. Could you explain a bit more?
     
  6. metin_mehel
    Joined: Jul 2009
    Posts: 158
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: turkiye

    metin_mehel mech.eng.

    The beams are made from Aluminium tube. They are connected by 2 bolts at each ends.
     
  7. gonzo
    Joined: Aug 2002
    Posts: 14,984
    Likes: 824, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    What are the means of propulsion?
     
  8. metin_mehel
    Joined: Jul 2009
    Posts: 158
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: turkiye

    metin_mehel mech.eng.

    Paddle, motor and gaff rig but I did not included the sail plan yet
     
  9. messabout
    Joined: Jan 2006
    Posts: 3,113
    Likes: 279, Points: 83, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    That appears to be relatively small boat. It will be weight sensitive. The Center of bouyancy is well forward of the helmsman. The tail will drag. Ama appears to have flat bottom. That configuration has the advantage of simplicity but it will have excessive wetted surface and higher form drag.
     
  10. metin_mehel
    Joined: Jul 2009
    Posts: 158
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: turkiye

    metin_mehel mech.eng.

    Correct... I supposed that the bags of the passenger will be put forward. And it would balance. This boat was designed for long distance trip near the costs.
     
  11. gonzo
    Joined: Aug 2002
    Posts: 14,984
    Likes: 824, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Catamarans are simple because of the symmetry of the hulls. Proas require building two completely different hulls, which complicates things with no real advantage. The small hull will have a lower hull speed than the large one and more resistance at speed.
     
  12. metin_mehel
    Joined: Jul 2009
    Posts: 158
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: turkiye

    metin_mehel mech.eng.

    I did not understand why small hull results in higher resistance? Crossectional area that receives the fluid is lower. So the resistance should be lower.
    Did you mean the drag of the smaller hull creates the bending moment and it needs to be compensated by the rudder ?
     
  13. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    It won't. Wetted surface area is less, and wavemaking will be less.

    But of course less buoyancy in the small hull means higher drag on the larger hull.
     
  14. metin_mehel
    Joined: Jul 2009
    Posts: 158
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: turkiye

    metin_mehel mech.eng.

    outrigger has smaller wetted surface that means skin drag is lower. cross sectional area perpendicular the moving direction is smaller too means bluff body drag is lower (area^2)
    wave making is close to each other because the LOA of both are so close to each other.
     

  15. TANSL
    Joined: Sep 2011
    Posts: 6,380
    Likes: 338, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    I'm not sure what Gonzo means by this: "The small hull will have a lower hull speed than the large one and more resistance at speed". But I think there is no scientific basis to say that.
    Since the two hulls are rigidly connected, it is not possible that one has less speed than the other.
    The resistance has several components, friction, formation of waves, appendices. Which one is higher in the smaller hull?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.