Newbie here came from a lowrance the last 10 years. Running two Helix 10s G2N Megas Si at dash and Di at the front linked. Some of the lakes I fish aren't on Jake master so the auto chart is goons be great for me. Do I have to have anything special to save this mapping to? I know it will hold 8 hours but say if I have 30 will any sad card work or do I need something special. Will the two units share what I have mapped ( will I see it up front too?)