a 200 ducer is best for the bay as it has better definition on the screen and is better for shallow water. The 50 ducer is best for deep water like in the ocean unless you want to track your deep lines(wider cone angle)-------------
If you buy a unit that supports both 50 & 200 you'll be doing yourself a HUGE favor. I can run split screen with both on my furno and that way I know when the fish are directly under the boat. Then you can also invest in a 360 degree scanning sonar that lets you see everything around and under the boat. ONLY $15,000 this week.