The issue with option 1. is that the HDS will only record positions in the sonar log file with approx 1m (integer Mercator(ish)) resolution. You might find, however, that full resolution position is recorded in the trail files, which you can export with depth, so if you are only looking for depth and position information this approach might work, but it won't help much with sidescan mosaic.We have a solution coming for post-processing separately recorded position and sonar logs to synchronise them, which works around this problem - but it won't be available for a little while yet.