I've been meaning to post this link for a couple weeks now. There's not a lot of good information out on the web concerning reading depthfinders, and what is out there usually takes quite a bit of searching to find. LTBama has been working on some really nice stuff that is sort of a summarizationn of what he has posted over the past couple years on the BFHP. There are currently 6 parts to the series at the moment. When you have some time, check out the link below to get you where they have been hosted.