He was able to take out two ships, yeah. But I'd like to think the BC would put up more resistance, especially since it's not exactly up against a cannon. From the Skypiean dials, we've seen nothing that could take out a ship save Reject, and that wouldn't work well for a few reasons.
If he uses impact dials to propel projectiles, say the size of a baseball, shot through his Kabuto then I could definitely see Kabuto destroying ships. If you've seen the G8 arc, recall how just 1 impact dial was enough to propel the entire Going Merry into the air - yeah I know G8 was filler, but it gives you an idea of the power behind impact dials. Imagine how fast a projectile pushed by one of these impact dials would travel. Now imagine how fast a projectile would be when pushed by six of these impact dials, radially arranged around a hoop. See my illustration below (blue ellipses = impact dials, black ball = projectile being shot through the hoop, green = hoop, which would be snapped-onto Kabuto somehow, i.e. it's an add-on). You'd potentially have a miniature M1A1 Abrams tank cannon (maybe even more powerful than that) in the palm of your hands.
http://img214.imageshack.us/my.php?image=illuszv5.jpg
The faster a projectile travels, the more kinetic energy it has, thus the more 'explosive' it is. That's the physics behind tank fire. Tank fire is extremely 'explosive', not because the ammo is explosive, but because the projectiles fired are extremely fast. Yeah I know I'm getting a bit technical here, but that sort of physics appears to be at work in One Piece (also in many other Shonen manga as well). How else do you explain exploding cannonballs?
Now you may ask if Usopp had such power, why didn't he use it against Jyabura? The reason is the kickback produced from such a weapon. One impact dial was able to do a number on Usopp's arm. Imagine what six of these, all activated simultaneously, would do to Usopp. Kabuto would probably need to be planted in place somehow to reduce the danger to Usopp's arm when using such a weapon.