How to choose a GPS Fishfinder Combo

The beads of sweat that are running down your brow from trying to make up your mind to purchase a GPS Fishfinder for the first time are not without reason. The world of consumer electronics is full of vast claims and unrealized results when you enter in. This is a guide to help you sort fact from fiction about GPS Fishfinders. Like all electronic hardware there is an underlying expectation that the device will perform as is stated in the features lists that are shown for individual units. However, there is a set of things that you need to know before ever approaching the point of evaluation or purchase.
The first consideration is about the type of boat where you are going to use the device. This knowledge has two components. First is where are you going to mount the display and the second is where are you going to mount the transducer for sending the signals into the water for the fishfinding capability. The display location should be close to where you steer the boat (the helm). The display location is critical for the GPS operation. GPS operation requires line of sight to the sky. In other words the radio signal from the satellites that send the GPS signal must be able to reach the GPS receiver. If the particular unit that you are evaluating has an internal GPS antenna, then the display must be mounted so that there is no obstruction between it and the sky, If you can see the sky through a window an internal attenna will work fine. Most of the boats that have wood and canvas cabins allow the GPS radio signal in. Cabins that are made from metal and some that are made from fiberglass reflect the signal and then one needs a unit with an external GPS antenna.
The transducer mount is another major consideration. The transducer needs to be mounted so that it sends the signal straight down into the water, which means that the transducer needs to mounted in the water and its lower surface needs to be parallel with the water's surface. Most of the GPS Fishfinder Combos sold today are prepackaged with a transducer that is transom mounted. This is fine for most power boats. However, this is not fine for sailboats and boats that have a lot of stuff already mounted on the stern of the boat. The manufacturers have taken this situations and have a full line of transducers that can be mounted inside the hull for fiberglass boats and through the hull for sailboats and large yachts. The transducers are also made from a variety of materials such as plastic and bronze with each having their strengths and weaknesses.
So, now you know the location of the display, the type of GPS antenna you need and the type of tranducer that you need you can evaluate each GPS Fishfinder Combo for specific features that you would like. I would like offer some other considerations that are benefits rather than just features. A benefit of having a GPS Fishfinder is boating safety. If you know where you are on a river, lake or ocean you can avoid hazards that are unseen underwater. The GPS Fishfinder can store the location of your favorite fishing spot so that you can return to it time and again.
Another benefit is to answer the question what type of sonar beam (sound wave) you should have on your unit. Sonar beams are either narrow sharply focused or wide area focused. If you do most of your fishing in shallow water (0-100ft) then a wide beam unit would give you better results than a narrow single beam. Some GPS Fishfinders have wide and narrow capabilities and there are units that have up to four different beams so that you get the maximum area coverage to the forward, rear and to side of the boat. The multiple beam units increase boating safety because the can alert you to objects in the path of the boat. The power of the transducer is another factor and benefit that you may need. A higher power transducer gives detail on the display at greater depths. This may help those interested in locations of underwater wrecks. The evaluation is now up to you for screens and features. Have fun fishing and catch the big ones.
.