what is the diffrence between the 78s and the 78sc,
Looks like it's just the installed maps. Here's a comparison of the two models on Garmin's site (link)
i run a dive boat in the florida keys,are those waters included with the purchase or do i have to purchase additional charts.
From the product page (link
) :Explore Coastal Waters
GPSMAP 78sc comes with built-in BlueChart® g2 coastal charts and a worldwide basemap with imagery — perfect for all your outdoor pursuits. Map detail includes shorelines, depth contours, navaids, harbors, marinas and more for the U.S. and Bahamas. And, like the rest of the 78-series, 78sc is IPX7 waterproof and even floats in water.