Neither of my fishfinders have maps or navionics. But I do have a spare tablet kicking around and was curious if Its possible to purchase a map or navionics for it and use it on the boat?  Thanks Lee

Yes, Navionics Mobile App.. I have it on six devices. Navionics Boating annual subscription.

The issue is sunlight viewability with your tablet.

There is an iOS and Android app.

Forgot to add you need a device with GPS or add a blue tooth GPS antenna.

Yes! its a great app. I have it on my iPhone 6 and I set it up as a hotspot for my Ipad. I paid for the subscription and you get a very detailed map. Shows you GPS position ( up to some error but not much) & speed,  great for night or foggy days. and allows you to edit the map to current conditions.  App 10/10