I always try to create a mental picture of the scenery down below when I’m fishing, but it’s often difficult to do. Charts generally are OK for a general impression of things, but nowhere near detailed enough. Likewise sonar gives plenty of detail, but it can be difficult to interpret properly if you’re changing course much.
A few years ago I stumbled upon DrDepth, a nifty piece of Swedish software written by Per Pelin which pulls together GPS and sonar data to create a personal chart of the areas you fish. At 99 euros it provided many hours of “fun” playing with the data I accumulate during a fishing season and given genuine insight into some of the places I fish.
Unfortunately DrDepth was too good and was eventually sold to one of the big sonar manufacturers to form the basis of their on-line charting software, so is no longer available for sale. It still works fine for existing customers, but isn’t obtainable for anyone becoming interested in creating their own seabed maps.
More recently the UKHO has started to release some very useful and detailed survey data, and I’ve started to make use of the excellent Reefmaster software to generate chart files that are directly usable in Lowrance chartplotters and which show much more detail than the conventional Navionics charts.