HDSS ocean velocity
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There is an offset in measured velocities at low ship speed.
    Of all calculated ocean velocity data, ocean velocities 
    calculated while the ship is stationary should be closest
    to 'correct', because any error that is proportional to 
    measured velocity will be as small as possible.  It is therefore
    difficult to understand why HDSS "on-station" measured velocities
    exhibit a bias.  

    Examples:
    (a) HOT149, (June 2003), using a two-beam solution (beams 3,4).  
        The offset was about -.1m/s (in the ship's forward direction)
    (b) HOT149, (June, 2003),using a two-beam solution (beams 1,2).  
        The offset was about +.05m/s (in the ship's forward direction)
    (c) P16S, (Jan/Feb, 2005), using a two-beam solution (beams 3,4).  
        The offset was about -.05m/s (in the ship's forward direction)
        

    The offset was calculated by comparing the measured velocity 
    in the ship's forward direction 100-250m  reference layer, to
    the comparable NB150 data.  See email_HDSS_report4.txt