Scott,
Yes, AutoChart Live on the ONIX units will map what the boat passes over and no map or memory card is needed for this. However, there is a limit to the amount that it can record, it is not limitless. If you are thinking about mapping many bodies of water you should look into the AutoChart / AutoChart Pro software for your area and start making sonar recordings (which you can do with your 898 unit and a memory card now for use later).