Love backups
Having "lost' the radar, as in lockup/out in bad weather while using my Raymarine SL72RC or, now, the SL 70 RC, the problem effectively denied me the use of the chart plotter as well. Fortunatley, I had a backup handheld and now carry two handhelds plus lots of batteries as cold temps severely degrades battery life. But, the ultimate back up is/are charts and a running DR