On Mon, 02 Sep 2013 07:36:12 -0600, slide wrote:

An iPhone or Galaxy can display GPS data when out of range of a
cell tower?

===

Absolutely, right in mid-ocean.

Most smart phones have a built in GPS receiver these days, and there
are some very decent charting packages available. For about $25 to
Navionics I have a full set of US and Caribbean charts on my Galaxy
along with a fairly decent little plotting application. You don't
even need a cell phone account to do all that, a WiFi connection will
suffice.