Robert, move this to another discussion topic area if you think it needs to be elsewhere. Question to Martin. for the side imaging : are you using the tan when computing the lateral distance from the boat centerline? I ask because I am looking at the silent part of the bottom not covered by the signal cone at 86 degrees? This will tell me the uncovered area and where to run the parallel course on the next pass. The humviewer shows the reading but I just wanted to make sure we were on the same calculation function. Thanks, Chuck