This is one of the smallest Humminbird units with SI and DI technology on it, and also one of the cheapest fish finders available featuring these options. Similar to the other Humminbird fish finders within the 300 series, the Humminbird 398ci SI Combo is equipped with a small screen 3.5-inch in diagonal, 320×240 pixel resolution, LED backlight, full color.
This unit has a power output of 500 watts RMS, (4000 watts PTP). It’s equipped with a Dual Beam Plus sonar, just like the 386ci Combo, with SwitchFire technology, which can be operated at 200 kHz/20° or 83 kHz/60°. Both 20° and 60° returns can be observed in split-screen mode. Although it’s specified to be reliable at depths of 1500 feet, accuracy in detail is reduced for depths over 600 feet.
All sonar readings are recordable and can be played later. Other functions, very useful for finding fish are the snapshot and waypoint recording options, this unit being able to record up to 2,500 waypoints.
The Humminbird 398ci SI Combo is also equipped with a precision internal GPS, therefore it can serve as a navigational tool. It has the basic Unimap pack, which covers mapping for inland lakes, inland rivers (30 m / pixel) and the continental U.S. coastline. It also features a single SD card slot, for Lakemaster, Navionics Gold, or HotMaps cards.
Although this unit is listed as waterproof, like most of the other units, it’s best to keep water out of it a much a possible, especially salt water.
Last but not least, the 398ci SI Combo has a tilt and swivel, quick disconnection system, permitting a better operability. It has a one year warranty.