your depthfinder gives a markedly different depth, you've learned  that  your  estimated  position  is  almost  certainly wrong.  in short, your Aqua-Probe digital provides a very valuable safety check. In combination with other aids It    almost    goes    without    saying    that    a    high    quality, accurately compensated compass is absolutely essential for  any  piloting  and  navigation.    No  boat,  even  a  small runabout, should venture offshore without one.  Although good fixes can be gotten from a line of soundings, more reliable  fixes  can  be  obtained  by  combining  soundings with    other    plotted    lines    of    position-namely,    cross bearings.  These can be visual (Aqua Meter compasses- with  exclusive  "Nava-Grid"®  course  and  bearing  lines- double  as  good  bearing  compasses).    Or  they  can  be electronic, or both visual and electronic. A  radio  direction  finder,  a  compass  and  a  depthfinder complement   one   another   very   effectively.      The   most simple procedure is to obtain your RDF bearing and plot it  on  your  chart.    You  then  take  a  depth  reading  as simultaneously as possible, correct it for tidal difference, and check along your plotted ROF bearing for the depth obtained.    Unless  there  is  more  than  one  such  depth  in the vicinity of your bearing lines, you have your fix.  The best  fixes  use  three  widely  spaced  bearing  lines  that converge  on  a  tight  triangle.    The  Aqua  Meter  Aqua- Guide®  ROF  is  a  first  class  navigational  instrument  that can,  with  practice,  provide  exceptionally  accurate  RDF bearings. Experienced   boat   pilots   and   navigators   check   their positions  continually,  and  use  all  available  electronics- even In good weather, to assure reliance and confidence if    the    weather    turns    bad.        They    consider    their depthfinders, compass and other navigating instruments to be completely indispensable. Small boat use/anchoring Even    up-to-date    charts    are    not    much    help    in    an anchorage.    Local  silting  or  dredging  may  have  gone unreported, and the quality of the holding ground may be quite  different  from  that  noted  on  your  chart.    Also  it's useful  for  finding  shelter  in  adverse  weather,  or  finding new  and  secluded  anchorages,  or  unmarked  channels, or for feeling your way into an unfamiliar dock. So far we have been talking about piloting bigger boats, but your digital depthfinder is equally useful for exploring uncharted   tidal   estuaries,   shallow   marsh   areas,   and small  uncharted  rivers  and  lakes  with  a  small  boat.    It can  open  up  new  territories.    It  can  make  your  boating very   much   safer-even   in   so   called   "protected"   inland waters.    Since,  as  we've  said,  digital  depthfinders  make no    predictions,    always    proceed    at    low    speeds    in uncharted  and  unfamiliar  waters.    For  instance,  it's  an excellent  idea  to  look  for  shallow  water  or  underwater obstructions  before  water  skiing.    It  can  save  a  lot  more than  a  broken  prop.    In  other  words,  your  Aqua-Probe digital  is  an  extraordinarily  versatile  instrument.    It's  the one piece of electronics that's as valuable on high speed runabouts as it is on a big cruising boat making a landfall day or night. Always available No  matter  how  quickly  a  fog  rolls  in  or  a  rain  squall obscures visibility, the bottom with its characteristic, tell- tale  contours  is  always  there.    Your  Aqua  Probe  digital depthfinder is one of the most reliable and nontemperamental  electronic  instruments  ever  made.    It can  be  used  virtually  every  minute  of  the  day  or  night. Few  things  in  life  are  as  reassuring  as  being  able  to know  with  certainty  how  much  water  is  under  your  boat at  any  given  moment...  or  being  able  to  learn  exactly where you are in thick weather.  Your Aqua Probe digital can  put  -this  knowledge  at  your  fingertips;  it's  a  great confidence builder. The  quickest  way  to  learn  depthfinder  navigation  is  to watch  experienced  navigators  use  it  routinely.    Failing that,    it's    a    good    idea    to    practice    comparing    your depthfinder's   readings   to   charted   depths   when,   from buoys or ranges, you know exact position on your chart. It's also a great way to study charts and sharpen piloting skills. 18