[C320-list] Boat Speed

[Walter burnett]

All,
   
  It occurs to me the many variations in reported boat speed is likely due to variations in the speed sensor calibration, or lack thereof.  The only accurate way to calibrate the boat speed sensor is by timing multiple passes ata a constant speed through a measured course in slack water and opposite directions.  Average the runs, calculate the speed and compare it to the readout for a correction factor to enter into the display. The more and longer the runs, the more accurate the calibration.
   
  In my experience the speedo out of the box can be off as much as 25%.  I suspect most boat dealers don't make any effort to calibrate the instruments before delivery and many skippers either don't know or don't bother. 
   
  Walter
  Selkie #887

		
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