title: The physics of turning in a boat
body: <p>I am writing a small simulation of a boat (a sailboat under power rather than sail).  It has a rudder and a keel and I have most of the physics working for the thrust and drag.  I have modelled the drag across the boat to be higher than along the boat to reduce the sideways slip.  </p>
  
  <p>However it doesn't behave quite right. Am I right in saying that the keel will not only provide resistance but also contribute to taking the boat through the turn by channelling water?</p>
  
  <p>The final model doesn't have to been scientifically accurate it just needs to "feel" like a boat.</p>
  
  <p>Any pointers would be greatly appreciated.</p>
  
  <p>Best regards and thanks in advance.</p>
  
  <p>Dave
  <br/></p>
  
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  <p><strong>EDIT</strong> (Originally posted as an answer by the OP)<br/></p>
  
  <p>OK, realised I'm missing the hydrodynamic "lift" generated by the keel. Seems like it acts like a sail underwater and generates a force vector proportional to the flow of water over it and the angle of that flow. The force vector is in the opposite direction to the movement of water across the keel and toward the direction the boat is pointing. In theory this should reduce the sideways slip and also pull the boat through the turn.</p>
  
  <p>Would appreciate if anyone out there who knows about this stuff if they could add an answer that makes some sense of my basic understanding. I am trying to distill this down to a formula that is related to the direction the boat is pointing and the direction and speed of travel of the boat.</p>
  
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  <p>OK, realised I'm missing the hydrodynamic "lift" generated by the keel.  Seems like it acts like a sail underwater and generates a force vector proportional to the flow of water over it and the angle of that flow.  The force vector is in the opposite direction to the movement of water across the keel and toward the direction the boat is pointing.  In theory this should reduce the sideways slip and also pull the boat through the turn.</p>
  
  <p>Would appreciate if anyone out there who knows about this stuff if they could add an answer that makes some sense of my basic understanding.  I am trying to distill this down to a formula that is related to the direction the boat is pointing and the direction and speed of travel of the boat.</p>