This GPS is not suitable for marine use

I purchased the Garmin GPSMAP 176C with the intent on using it on the water and also on the road. I have been VERY disappointed with this unit and Garmin for the following reasons:
1.The power cord disconnects from the unit in a VERY light chop (This cuts the unit off... you have to plug it in and restart and wait for the unit to acquire a new signal)
2.The marine base map is awful (the shorelines are extremely inaccurate) This caused me purchase an additional $116 data card that is still deficient
The Lowrance standard base map is better than the Garmin $100 map
3.The land base map is just as bad for anyone who travels mostly in the US (a lot of memory wasted on useless data in Europe and Asia)
4.The car adapter is expensive (this should come standard with a $599 unit)
5.The battery life is poor (especially with the backlight that is needed in any low light situation)
6.Customer support is unhelpful

I have never written a "bad" review on a purchase before, but this unit is just that bad. I wish I would have gotten a Lowrance for the boat and a dedicated "automobile" GPS for for the car, I probably would have spent less money