Some anglers may want to go with a combo unit which includes sonar and GPS. Portable units can be put together for around $400 to $700 dollars, again depending on size and screen choice. Units such as the Eagle FishElite series 642c, 640c, 500c, 502c, and 480 fit these criteria. Garmin offers the GPS Sounder 398C. Humminbird options include the 767 or the 787 c2. In the Lowrance lineup are the LMS-334c, LMS-332c and the LMS-480m.

Many anglers who already have a good sonar or combo unit on their boat remove it, buy a portable power-pack with the suction cup transducer, and create their portable system with minimum additional expense. This also gives them a unit they're already familiar with.

There are a few things to consider when selecting a portable unit. One is the type of fish you are pursuing. If you are primarily a walleye or bass fisherman, the power output of most units is adequate. Should you pursue some of those Boundary Waters or Canadian summer lake trout, a unit with 1500 to 3000 watts of peak-to-peak power better suits your needs.

Also consider your power source and battery life. A rechargeable battery requires a way to recharge it. Many of the fly-in lakes that I have been to do not have cabins with electric power. However, this is slowly changing. Last year, Nestor Falls Fly-In Outfitters began to install solar panels on some of their cabins providing some power options. I have used a 1500-watt sonar unit that ran on 8 D-cells. It worked for at least 5 days of fishing. If you're using AA batteries, your operating life is less.

Running your system with the backlight on reduces your operating time by 40 or 50 percent. Be aware that the new color TFT (Thin Film Transistor) screens use more battery power than the conventional monochrome screens. I've used a small portable color unit that ran on 8 AA batteries and found to my surprise that a set of batteries lasted for about 10 hours of fishing. In a matter of several days I was getting batteries from everybody's GPS units and flashlights. Expect to have battery life reduced by 30 to 50 percent with color screens, compared to similar monochrome screens.

Portable sonar systems allow anglers to take their fishing technology with them wherever they go and put it on virtually any kind of boat or canoe. This is a convenience for the casual fisherman and also offers technology that the avid angler has learned to expect when on the water.

CONTACTS
Eagle Electronics, eaglesonar.com, 800-324-1354; Garmin International, garmin.com, 913-397-8200; Humminbird, humminbird.com, 800-633-1468; Lowrance Electronics, lowrance.com, 800-324-1356; Marcum, marcumtech.com, 763-493-3748; Vexilar, vexilar.com, 952-884-5291.

Bill Diedrich, Minnetonka, Minnesota, is a long-time contributor to In-Fisherman publications on electronics topics. He serves as the Electronics Doc, answering common questions on In-Fisherman's website. Bill and Bruce Samson run a Lowrance Electronics School, for which information is available at wdiedrich@earthlink.net.