@Creekdog5658 Yes you can, for the first time ever! You can start on water anywhere you like, by clicking a point on the world map, and then selecting “set as departure point”. Then from the top dropdown menu change your custom location from “airborne” to “on ground, shutdown” or “on ground, ready for takeoff”.
And that’s it. 
Ps: I recommend using “on ground, ready for takeoff”. The sim is not currently respecting the apronwater.flt file settings, so if starting on the water and in shutdown state, the pitot cover will be on. This will require some divine water walking outside to fix. 
I’m working on a workaround for an update though.