Posted by: Photobug on Oct-31-12 12:24 AM (EST)
I have a garmin Etrex. I have used it for a decade for sailing, kayaking and flying. I have also crossed the Gulf of Mexico using only an even older Garmin 12.
Even the most basic or oldest GPS will serve you well if you know how to navigate. If you don't the Garmin 76 series with moving map will help more. Some of these won't come with full marine maps, which you may have to buy. It will be worth paying more for model that has a map database included.
I have a droid Razr also and use Edmondo to keep track of my kayaking biking and running. I keep it in a waterproof drybag. It is nice to record my paddles but not as a navigation instrument.
There are some Nav apps for the Droid as well but I do not find it usefull as they are limited and I am not comfortable trusting a navigational need to something not completely waterproof and easily accessible.
The Iphone has better navigation software options, but once again the lack of waterproofing makes it of dubious use.