The Humminbird 688ci HD Combo is another unit with an excellent price / quality ratio. It’s the unit that comes to take the place of the similar, discontinued units, 788ci HD Combo and 587ci HD Combo.
This fish finder has the same screen format as the other other units within the 600 series, 5-inches in diagonal, 640V x 480H pixel resolution, high definition, full color with backlight. Has a power output of 500 Watts RMS / 4,000 PTP, being equipped with a Transom XNT 9 20 T standard transducer. It comes with a standard Quick Disconnect mounting kit, but can also be mounted on an In-Dash, optional mounting kit.
Also, similar to the other 600 series units, the 688ci HD Combo has Dual Beam Plus sonar, which can be operated in two modes, separately or simultaneously, for a 200 kHz / 20° or 83 kHz / 60°, with a depth capability of 1,500 ft. Although this unit does not support Side Imaging, Down Imaging or 360 Imaging, it does have SwitchFire, and still pretty much has all the standard features needed by any angler to measure depth, track fish, assess the shape of the bottom and know the water temperature.
Regarding its navigational capabilities, this unit has precision GPS, chartplotting and trackplotting, and comes with the UniMap cartography package built-in, which covers the contiguous U.S. coastline and inland waters at 30m / pixel. The unit can be upgraded though, with a SD card for Lakemaster or Navionics Gold/Hotmaps, but does not support Navionics Platinum + or C-Map. Its memory can store up to 2,500 waypoints, 45 routes and 50 tracks / 20,000 points each.