I have a Garmin chartplotter and an old Garmin handheld which both work for the GPS input using Sailcruiser, Seaclear, or Open Cpn. Just make sure you go into the gps setup screen to tell the software that you are using Garmin USB protocol. The only problem with using computers is getting them in a good position to see and manipulate on deck. A non-waterproof computer won't survive long after the first wave breaks over the rail. They also don't have the daylight viewable screens that chartplotters do. I bought a refurbed Panasonic Toughbook which is splashproof, has a daylight viewable screen and is pretty rugged but still prefer the little Garmin 376C chartplotter although the screen is small.
Alberg 35: With a philosophical flourish Cato throws himself upon his sword; I quietly take to the ship.