Gangplank Ult Physics

With the new Summoner's Rift map going into live beta, it's time to think about the reality of some abilities. Gankplank, whose ultimate depends on a ship off the map shooting cannonballs on the map. In the new map, the only water source that can be seen in a tiny river way way way down below the mountain top. Now if we suppose a huge pirate ship could fit on the river, the apparent height of this mountain is very high, and since the particles are seen falling straight down, then the cannons would have to fire the heavy cannons balls even higher than the map itself, which requires a ton of force, too much for a regular cannon. Now assuming that Gangplank had cannons that were able to do that, you can not see the ship itself in the river, which means it had to be beyond the horizon, making it realistically impossible to shoot the cannonballs that far and that high. On the other hand, the ship would have to be super close to the base of the mountain, making it very difficult to be precise enough to shoot to where Gangplank wants to ult, due to the almost vertical angle it would have, and being a few degrees off would mean the balls go straight up (and come straight back down on the ship) or the balls would either miss the intended target or hit the side of the mountain.