I started the Great Expedition questline and I need to kill a sea monster.  I'm using a  basic sailboat.  I supplied my ship so I have cannon balls.   I click the 'aim' button and  crosshairs come up, and I put them on the monster.whe. I fire the the shot always go 90 degrees to the side and a long distance.  I know it must be me and not a glitch in the game, but I just can't get it to work.