The cannonball will land 236.25m far from the ship.
Since we ignore any friction for this problem, the only force applying to the cannonball is its own weight (it's a free fall). Therefore, its acceleration is:
Since the cannonball is fired horizontally,
Since the cannonball is fired from a height of 17.5m above the sea level, then
We want to know how long it will take the cannonball to reach the ground:
Now, we want to know how far the ball can go during this time. Since the ball was fired at an initial speed of