Many marine electronics feature multifunction systems that already include GPS, such as GPS/fish finder combos and GPS/chart plotter combos.  Getting a handheld GPS for your boat might seem redundant if you already have a GPS/chart plotter combo or a stationary GPS but consider the benefits.
Unlike chartplotters or standard GPS receivers, portable units are a lot less expensive. Handheld GPS units are just as reliable and accurate as your other options so low price becomes a major benefit.
Portability is quite possibly the second most obvious benefit of handheld GPS. If you want to be able to use your GPS both on and off the boat, say in a car or while hiking, then you need a handheld unit.
On the other hand, small size has a major drawback – small screen and small buttons. In rougher weather conditions hitting just the right keys or making out waypoints might become difficult.
Another drawback of portability is that it implies having to rely on batteries to operate your handheld GPS. In addition to monitoring battery charge levels in your handheld and keeping replacement batteries handy, make sure to select a model that can run on external power as well as on batteries.
Even if you already have a GPS system in place, you might find a handheld unit helpful. For example, if you use a computer connected to a GPS receiver, you already know that you won’t be able to see much on your computer screen unless it’s below deck or otherwise shaded. By choosing a handheld GPS with a screen that can be read in …