Or you could try the opposite.
Do you have any friends you trust to do the sailing for you, which would allow you to do the flying?
The wideangle lens of the Phantom would mean that you'd have to get to close for comfort to really see much detail of who is on the boat.
Eliminating the issues of flying and catching from the boat, introduces new problems if you wanted to launch from land while sailing.
How close to shore would you be sailing?
Would you have an assistant to place the Phantom and turn it on when the time is right?
If you are relying on RTH to get it back and land, make sure the launch spot is clear for 20 ft around.
Here's a sailboat I shot last week just to stimulate your thoughts.