Does anyone know if there will be any gyro synchronization issues if we launch the Phantom from a rocking boat? Will stabilization be affected?

Interesting question.  I believe when you power up a Phantom the IMU performs a calibration process.  Not sure what would happen if the calibration is interrupted by movement.  It may fail to calibrate and refuse to fly.

I have not tried myself, but people do it. Make sure you learn to hand-catch (hand-land) (watch YouTube videos on it).

Hand catch is the only way I go.  No risk of an accidental bad landing.  I have had one or two times where when trying to power down the motors, the P3 flip onto its side.  No reason to break something when you can hand land.  

I do hand catch, thanks! hopefully we won't have to beach the boat for launch though...

Maybe we need a gimbal stabilized launch platform for boats...

So, I launched the P3 while beached on an island today. The boat was being rocked with heavy swells. Once it took off, it started drifting everywhere. I had to really, really concentrate in order to keep it stable enough for my son to hand catch it. Second time I launched from the beach, but it was still being affected  by the bad calibration on the boat. It wouldn't even launch, and the app demanded an IMU calibration. Verdict: Find calm waters or launch from stable ground. Don't launch from a rocking, heaving boat!

And now the question is : how do they perform this in one of the promotional video ???

Ulysse Posted at 2015-5-24 15:14
And now the question is : how do they perform this in one of the promotional video ???

One would assume they launched the craft from shore and flew out to the boat.
Apparently the previous versions of the Phantom didn't have such a sensitive IMU?