Efficiency SPP!

Discussion in 'Surface Drives' started by Salvatore84, Apr 29, 2012.

  1. Salvatore84
    Joined: Mar 2009
    Posts: 12
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Italy

    Salvatore84 Junior Member

    Hi,

    I am making a power prediction for a 45'. The propulsion system is the Arneson ASD 11, but I have no datas to estimate the propulsion efficiency for surface drives. I have the Pes from Savistky, and I don't know how to calculate the Pd.

    Thank you!
     
    Salvatore84, Apr 29, 2012
    #1
  2. jmiele3
    Joined: Jan 2012
    Posts: 33
    Likes: 2, Points: 8, Legacy Rep: 73
    Location: Philippines

    jmiele3 Junior Member

    jmiele3, May 1, 2012
    #2
  3. Salvatore84
    Joined: Mar 2009
    Posts: 12
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Italy

    Salvatore84 Junior Member

    Thank you John, it's very good for a general idea of the problem but not for a precise solution of the problem. I think that just the propeller builder can know this datas, I can't find them anywhere.
     
    Salvatore84, May 1, 2012
    #3
  4. jmiele3
    Joined: Jan 2012
    Posts: 33
    Likes: 2, Points: 8, Legacy Rep: 73
    Location: Philippines

    jmiele3 Junior Member

    Salvatore: Unfortunately, the formula we use is based on tunnel test data. Rolla usually makes the propellers for Arneson (Assuming the athe original propeller is in place).
     
    jmiele3, May 3, 2012
    #4
  5. PetterM
    Joined: Sep 2004
    Posts: 211
    Likes: 9, Points: 28, Legacy Rep: 201
    Location: Norway

    PetterM Senior Member

    What P/D range does your model data cover?
     
    PetterM, May 3, 2012
    #5

  7. drailton
    Joined: Jul 2012
    Posts: 11
    Likes: 5, Points: 0, Legacy Rep: 68
    Location: Vietnam

    drailton Douglas E. Railton

    Generally the efficiencies of an ASD equipped boat range for 55-62%. Selection or the proper gear ratio and propeller shape vs speed play a big role here. Surface piercing propellers generally have their highest efficiencies with a P/D between 1.2-1.5.
     
    drailton, Jul 13, 2012
    #6
    1 person likes this.
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.