I have 3 Lowrance Gen 1 units on my boat. I know they are old, but they still work good. I have noticed that the maps are not real accurate when it comes to the contours. It always seems to be off. The lines seem fairly accurate, but they seem to be off, one way or another, to one side of it. On smaller lakes I fish it doesn't seem to be a big deal. Last night I fished a lake that transitions from 5 feet of water to 60 feet of water very quickly. I wanted to troll that 14-20 foot area, but I had hard time staying on it due to the map not being accurate. Two the units have the built in Insight and one of them I have chips for. They all seem a bit off.
Has anyone else had this issue? Is it normal? Is there anything I can do about it? Is it the gps accuracy or the map overlay?