Every year, a weedline can move. Maybe a few feet, maybe gone. My GPS is standard equip when I ice fish. Of course you can use it for markin waypoints such as dropoffs, bottom changes, ledges, rock piles etc.I dont winterize my fishin boat till december, for the the simple fact... I try to wait as long as I can, THEN go out and mark what weedlines are left. I JUST winterized it a few days ago. I had it out on bass lake and maxinkuckee. Of course on these lakes its not so much findin the weedlines, but the suttle breaks, and curves next to structure where these weedlines are. With the 29 str8 days of above normal temps we have had, the weedlines are not dying off as fast as they usually do. But I waited as long as I could, I had to winterize for this weeks temps. I did however find a couple spots to mark. 8)