1600 ton license studying

Looking for the best resources to study for the 1600 ton exam - particularly the nav section. What worked for people?

marineradvancement.com and www.uscgexam.com

with the above you pay one time.

Lapware.org is good too but you need a internet connection and pay monthly.

Never have been an iphone user but i hear upgradeu has worked well for some folks.