Chartplotters versus Fishfinders
There is a common misconception that chartplotters and fishfinders are one in the same in the world of GPS devices. However, this is simply not the case. Although the two different types of GPS devices do share some similarities and features, they are distinct in their own unique abilities. It is important for potential users of these GPS devices to understand these differences in order to get the most out of their GPS device(s) and ultimately, the most out of their marine experience.
A chartplotter is a device is used as a navigation tool in that they will plan your route for you, redirect you if you get lost, and provide very accurate information about your exact geographic location.  It is also equipped to search for all relevant charts and maps for your particular location and proceeds to create an easy-to-follow route, i.e., one that avoids shallow water, buoys and any other type of obstacle that may hinder one’s trip. The display unit clearly shows  latitude and longitude, which is a very important thing when one is in the open sea. Most models include world-based maps for easy navigation and location abilities no matter where you take your trip. Essentially, a chartplotter is used to plot out routes and ensure that you are getting to where you  need to be. Although some charplotter devices do contain fishfinders, they tend to be more rudimentary and less accurate than a GPS device strictly made for finding fish.
Fishfinders are GPS devices whose main purpose is to pinpoint the location and depth of the fish that you are trying to catch. They are able to distinguish the difference between bait fish and fish that you actually want to catch by using echo-location. This data is then sent to the display device, telling you where the right fish are and how deep into the water they are located. Almost all models can be used in either fresh water or sea water, which is very conveienent for people who enjoy fishing in lakes and in the ocean.
Clearly, the two GPS devices are very different from one another. While chartplotters are very useful in getting one where they need or want to be, they are not the ideal tool for finding out important information about the location and  types of fish that need to be caught. On the other hand, fishfinders will not provide the navigational features boasted  by chartplotters. So, for the ideal fishing experience using GPS devices, it is ideal to have both a fishfinder and chartplotter to ensure a successful and enjoyable trip on the water.