Off your own ship, in the water!
 

I figured out how to exit your own ship into the water without a ship. If you have a Sloop, go to the far left hand cannon. Go onto the right side, and start running. You'll end up off a ship and in the water! I believe you may be able to board another enemy ship by doing this.

Jack show you that?

ive done this i will right instructions on how to do it:

First you can have a sloop or any type of frigate for this(on the sloop go to left side cannon as said above and on war frigate go on the cannon on the left right at the front)go to the cannon you need start jumping at it or running at it if its not helping go on the cannon shoot on the lowest to the left 3 times get off the cannon and it should shoot on its own repeat the jumping and running thing if it still not working keep pressing F5 if its still not working do all of these at the same time

I tried to board another ship, but it was moving. So, it was pushing me back with it! It was hilarious!

Lol captain monkey thats the annoying thing. guess what i flew onto an enemy ship and it sunk and i didnt go to jail i just went under the sea with it!