DBK - Depth Below Keel

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 $--DBK,x.x,f,x.x,M,x.x,F*hh<CR><LF>

 Field Number: 
  1) Depth, feet
  2) f = feet
  3) Depth, meters
  4) M = meters
  5) Depth, Fathoms
  6) F = Fathoms
  7) Checksum