Tom, I'm gonna answer your question assuming you might be new to coastal navigation, based on reading into the questions you asked. If you are not and I misread that, forgive me, as I am not trying to be the end all-be all of navigation knowledge. I'm not. I was involved in a scenario soee years back though, sailing with some folks that took coastal nav very lightly, were totally dependant on GPS, and got themselves into a pickle that could have had a real bad outcome. It truly was an eye opener for me that prompted me to step up my game a bit. I suppose I am kind of a soap box guy on this topic and folks are probably tried of hearing me harp about the awesome upside of using GPS vs the always possible down side.....but...here goes... ;-) Almost any handheld will work for you as long as you are using it as an adjunct to a basic coastal navigation skillsset. For many years Jo and I sailed with a Garmin that strictly gave digital info and had no chartplotter. The key factor there is that I had a chart and was using the GPS to compare the Lat/Long of my current position indicated by the GPS to where I already was pretty sure we were by basic dead reckoning navigation. Nowadays most gps units incorporate some type of chartplotter screen making it even easier to navigate, but also easier to get into trouble should there be an issue with the GPS (battery, loss of signal, equip malfunction, etc). The question of "how do I know when I'm offshore....." falls back onto having a chart handy and knowing your position on it with or without the gps. I am currently using a Garmin 476, as well as an iPad running Navionics charts combined with a "Bad Elf" GPS receiver for iPad. Both are incredible tools, but they are both always used with a hand bearing compass and a chart that I am following along on.  I would imagine that the recommendations you will receive will be as varied as can be. The good thing is that if you are using the GPS as just another tool in your navigation tool box , rather than the entire tool box, virtually any modern GPS will fill the bill. The differences really come down to preferential details like screen size and visibility, ease of manipulation of the buttons, and how you feel about the way that particular unit makes you navigate through pages and menus.  Most people, myself included...fall back to recommending the particular unit they themselves have, because they've used it, become familiar with it, and are resistant to change. I, for instance, am a "Garmin guy" cause I know and understand the logic of how to move through the Garmin menus and screens. But that surely doesn't mean there are not some other great units out there. The important thing still falls back on this....you should be able to make any trip you are planning to make with a GPS,...... without the GPS.  If that is the case, any brand GPS is gonna make life just that much easier and safer! And...when you compared your position on that you are pretty sure you are on the chart , to the position indicated on the GPS and they agree...well THAT is a good feeling! S Sent from my Verizon 4G LTE Smartphone