Dan or Judy Kernell wrote: For navigation I prefer to have a Raymarine, Garmin or others with communication to the auto pilot. We love picking a waypoint on the chart and letting the auto pilot take us to within 10 feet. >>>>>..................... snip ............ <<<<< If you can not trust the charts for navigation - what do your trust. When I travel between day marker to day marker or other navigational aids I have to trust the people placing the day markers. It is great to use the auto pilot that has a track feature to adjust for wind or current. >>>>>>>>>>>>>>>>> end snip <<<<<<<<<<<<<<<<<<<<<< REPLY Its your comment "letting the auto pilot take us to within 10 feet." which is a bit over optimistic. Having been involved in both surveying in the field and also seeing how electronic charts developed from about 1991 and forwards I can say that such trust in the total accuracy of all charts is not always warranted Depending on where you cruise the actual chart may be based on data surveyed several decades back. Raymarine and Garmin bases their charts on data provided by the hydrographic office. What is worse is the development of seamless charting. That disguises exact chart borders and boundaries. On a paper chart you can read in the title block who did the survey and when. Furthermore many charts actually include the bench marks used in doing the survey. This allows the astute user to confirm for themselves exactly how reliable the chart is. With electronic vector charts such as Raymarine Furono and Garmin uses this is not possible. All charts electronic or paper starts with a survey crew in the field to verify an documentt all position data of charted objects. As has been mentioned by others ATONs are relocated as a result of silting and current scour. The paper work documenting these changes takes awhile to work their way through the system. What you see on a chart only reflects what was there on the day the survey was made and that could have been a long time ago. Secondly is the issue of absolute accuracy. There are several sources of errors inherent in the process including such things as datum correction and Signal latency. I used to cruise in an area which had no know datum reference. The original surveys dated back a century or more. Subsequent revisory surveys used visual refence points like bench marks but none of it had until then been double checked against WGS 84 datum with GPS. In order to bring this whole area up to date with GPS required a totally new triangulation survey; a very time consuming exercise requiring many people and much time. Meanwhile companies like C-Map and Navionics were selling electronic charts based on these old flawed surveys and presented on paper Both Navionoics and CMap digitized the paper to create their own database. I personally documented a set of navigation buoys that were one whole mile out position Despite reporting this fact the the VP of Navionics it took 2 years before the electronic charts reflected the true nature of the situation. Prudence suggest you not rely on accuracy closer than 100 feet unless you have personally verified the ground truth of the position by having been there before to survey it. Arild