Rudder Area In Clr. Calculations ?

Discussion in 'Boat Design' started by viking north, Sep 17, 2011.

  1. viking north
    Joined: Dec 2010
    Posts: 1,868
    Likes: 94, Points: 48, Legacy Rep: 1146
    Location: Newfoundland & Nova Scotia

    viking north VINLAND

    I thank you -- certainly going to push for the max. --Had a bit of luck last week at the used metal yard-- came across a 1.75in. dia 316 stainless shaft of the exact length I need with a balanced rudder blade welded in a slot cut into the shaft and the emergengy tiller square nut welded to the top all for the price of retail scrap stainless by the pound. Just have to fabricate a glass foil rudder blade over the present stainless blade. Got to love those metal recycling yards-- Thanks again--Geo.
     
  2. DCockey
    Joined: Oct 2009
    Posts: 5,229
    Likes: 634, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    What is the source of that formula?
     
  3. xlr8
    Joined: Oct 2011
    Posts: 14
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: water

    xlr8 Junior Member

    These are wildly used in Japan including major mass production builder.
     
  4. jehardiman
    Joined: Aug 2004
    Posts: 3,762
    Likes: 1,152, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Humm...yes...well. If you look at it wildly enough there is a twisted sort of logic to it. Water is ~ 850 times as dense as air. What the equation does set the rudder area force to the sail area force corrected by the effective lever arms assuming that hull speed^2 was 1/2 wind speed^2. Psudoscience perhaps, but to paraphrase: "all mathematical models are wrong but some of them are useful".
     
    Last edited: Oct 10, 2011
  5. DCockey
    Joined: Oct 2009
    Posts: 5,229
    Likes: 634, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Good job of deciphering it.
     

  6. viking north
    Joined: Dec 2010
    Posts: 1,868
    Likes: 94, Points: 48, Legacy Rep: 1146
    Location: Newfoundland & Nova Scotia

    viking north VINLAND

    So are junk rigged sails, in out traditional image of a sailing craft they look ugly and weird, not my cup of tea, but dam it they work and well at that. Different strokes for different folks as they say.--Like sails I'll stick to the simplier rule of thum calculations of rudder area-- not to say XLR8's is less accurate it's just i'm too dam old to be introduced to new tricks-- but thanks again XLR8 -- your post has introduced food for thought amoung others mathamatically more qualified than me :)-- Geo.

    A yacht is not defined by the vessel but by the care and love of her owner---
     
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.