If boat moving forward, launch from back with drone pointing rearward. Upon launch, drone will hold position and boat will move away underneath it. Get the combo wrong and the boat will sail into static drone. Think about it for a while!
Drop as much speed as you can for launching and landing.
Explain to the crew and plan with them. Practice communication.
For landing bring in backwards. Your right stick then mimics the drones direction so you're not having to think about reversed orientation.
Don't fly too far away or let the boat move too far. Exceed your range and your RTH kicks in but where is the RTH point for a moving boat!? Update your home point regularly.
Turn off downward sensors due to reflections off water confusing it. Maybe turn off other collision sensors otherwise it might think boat and rigging are obstacles and won't want to come near you and can't land.
You'll probably end up hand catching. Practice on land. Carry a heavy glove (welding gauntlet etc) if scared. For total emergency crash land into a loose blanket/net/hammock. You may lose some props but you keep your drone (and fingers).
How do you focus? On my old Mavic Pro I used to fly up to 30ft, point camera down and do an autofocus to the ground then switch to manual locking it off. Usually this set a good enough focus for most things near and far. However, this didn't work for me trying to focus on the sea from 30ft up (again, I think reflections confused it). I ended with a whole video of slightly out of focus shots:
It all sounds daunting but is possible. Practice on dry land through trees etc to simulate rigging, narrow spaces etc.
Good luck.
