Navionics chip

Can you update the mapping or do you have to buy an all new chip?

Mine is a $99 per year subscription. Free the first year. I buy the subscription every third year.

So if I have a chip I have to buy a subscription to navionics to update the mapping?

Yes. It is free the first year after you register the chip. After that, it's $99 a year. Which is why I only buy a subscription every three years. I only fish lakes Guntersville and Wheeler. So I don't need any other updates than those two lakes.