Yes, for longer range shots. For the middle of your range, you can't "aim up" that would not hit the target at the speeds needed. Lobbing rounds with a railgun is mostly worthless and can be done, as you have said, with a normal naval gun. So take your diagram (that has the labels wrong) and compare to an old one, from when battleships where still in use. See you are assuming that all ballistic curves are the same but the old 16 inch guns (for example) shot at 762 m/s vs the railgun that shoots at 2,220 m/s so the railgun will be more "flat" then the naval gun. Still a curve yes, but one that is now awkward when at sea. From what I was seeing this issue can be mitigated by moving the gun higher on the ship (its not by much the dart clips the waves) but that introduces new issues. The distance before something is "lost" over the horizon at sea is between 5 and 10 km (based on the height of the ship), at this range the railgun is still mostly going "straight" (its not but the drop is not enough yet). So if you want to hit something say 12 km away (in range of normal naval guns fyi) you would need to shoot so high that you would be putting the dart into a sub orbital trajectory and without guidance be lucky to hit anything (and good luck making a system that can withstand air at sea level when traveling at mach 6).