Hullspeed analysis - Resistance curve

Discussion in 'Software' started by bam_yat, Jun 18, 2013.

  1. bam_yat
    Joined: Sep 2011
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: malaysia

    bam_yat Junior Member

    Hi,
    I have run a resistance analysis for a utility boat, and the curve shown was like in the picture below. is it normal if the result like that?if wrong, can anybody tell me what are the source of problem?
     

    Attached Files:

  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 478, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

  3. bam_yat
    Joined: Sep 2011
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: malaysia

    bam_yat Junior Member

    is it?before this i compared with the curve of planning (fast patrol boat), its curve was smooth increased.
     
  4. Olav
    Joined: Dec 2003
    Posts: 319
    Likes: 46, Points: 38, Legacy Rep: 460
    Location: Filia pulchra Lubecæ

    Olav naval architect

    I don't see any obvious flaws. If you are concerned about the local maximum at about 21-22 knots (Fn = 1.1): This is a typical resistance "hump" that many - if not most - planing boats show during the transition from displacement to planing regime. Trim angle will be maximum as well at this point.

    It is possible to lower the trim angle with trim tabs or interceptors, which can flatten the hump quite a bit, helping the vessel get on plane more easily.
     
  5. bam_yat
    Joined: Sep 2011
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: malaysia

    bam_yat Junior Member

    thank you for the explanation. now i understand it.. :)
     
  6. daiquiri
    Joined: May 2004
    Posts: 5,373
    Likes: 247, Points: 73, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    If it is a curve of a 40-45 ft powerboat, it could be credible. In absence of further info about your project - as PAR said... :D
     
    1 person likes this.
  7. jehardiman
    Joined: Aug 2004
    Posts: 2,870
    Likes: 418, Points: 83, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    That shape is very typical of a planing boat with a Lp/Bpx of ~3. Go look at the Series 62 data.
     
  8. Alik
    Joined: Jul 2003
    Posts: 2,918
    Likes: 252, Points: 93, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    Take the prediction method You are using and program it Yourself, say in Excel. Then, You will know how it works and if the results are reasonable.

    Just pressing the keys in 'black box' software - not for naval architects/engineers.
     
    1 person likes this.

  9. Crowsnest
    Joined: Jun 2012
    Posts: 44
    Likes: 1, Points: 0, Legacy Rep: 18
    Location: Madrid

    Crowsnest Junior Member

    Looks like a reasonable curve for a 10-12 meters planning boat.

    LwL= 1/g (V/Fr)²

    Regards
     
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.