Originally Posted by ciaranp
Are the maps fairly detailed? Is the internal antenna sufficent enough?
Did you add any maps?
whats the difference in the 550 to the 551?
Pre-loaded chart detail is equivalent to the normal Garmin Bluechart, so yes, very detailed. The plug in G2 Vision charts add land detail, sat imagery and 3D views, which you won't get on the pre-loaded mapping.
Internal antenna is fine on an open boat. If the unit were to be used in a cabin, then an external antenna would be the way to go. Unlike older Garmins, all 550/551 units have the internal antenna as standard and an external antenna can be purchased as an aftermarket accessory and plugged into the back of the unit.
The 551 has NMEA2000, whereas the 550 has/had Garmin caNet instead. The 551, according to Garmin, has a faster re-draw speed. Both units have NMEA0183
Good value units.