I have the 565 too. At 40' I can mark my double-uni knot.
Joey, There are several things that can effect the clarity of these units. If the transducer is not pointing DIRECTLY down toward your bait, it won't mark it as clear. There's a bunch of settings that will affect clarity too, such as bottom zoom, bottom settings, and sensitivity.
Do you ever fish the Alcona area? If so, we can meet up one weekend, and I can show you all the tricks..