The ducks land weapon is a slow, inaccurate cannon. Though technically a torpedo IS a ballistic weapon when fired on land, you cannot make it fire at surface targets. The only way to make a torpedo fire on land is to make it a submissile: A torpedo that tracks even when in the air (IE treats everything as water).
If we also wanted it to be a slow projectile weapon in the water it could be done (Note, cannons are ballistic and lose range with height- IE, deep water). Ships are fairly easy to hit with such a weapon due to their large volumes, but they are also very fast. On a longer range weapon like the comm one, there is a good chance to miss. This is also going to hit hovers, ofc (In fact, duck should probably shoot its ballistic torps at hovers if we wanted to be consistent... but then everything should really because 'breaching' is VERY easy for torps).
Comm Torp probably just needs a buff. The only reason it needs to be usable on land is because of hovers, but if you're starting IN the sea you wont be able to fire your land weapon at them anyway. If you're going to be on land AT ALL you should use a jumpcom (Trivial to jump to/from sea away from either torps or hovers, and you can jump-to-shoot, which is why jumpcom doesnt have torps).