Seadeep, for a boat that size (where space isn't an issue) go with a fixed mount such as a Garmin 182 ($499) and get a second station kit ($30) trust me, you'll be glad you did. Besides a much larger screen than "any" handheld, which you can actually read when your bouncing along at 20+ kts. It takes a pre-programmed (garmin) Blue chip for enhanced detail where as the handheld you have to do the downloading off a CD-Rom to get detail, not a big deal but not as easy as just putting in a chip.
I see you live in Mukilteo, come by the Everett Boaters World and talk to me (Scott) Dave or Dale and we can give you a demonstration, and show you the plusses and minuses of each unit.