As Ben said if having difficult time reeling in fish and board ,slow down as much as you can.You can even shift in and out neutral to slow down more.But you have to keep moving forward or your other lines will snag or tangle.Most likely was not a large walleye,looking at all the charter boards of 30 -40 walleye for past weeks shows how rare a FO is now out west.Most likely a big sheephead,cat or foul hooked fish.But good job on first time trolling.Had to have fun with all that action.