Actually, it doesn’t matter if the boats are atomic scale or not. The chance that this could happen is still non-zero (just really, really, really small).
Well it is possible that the boats were built on an atomic scale, and the missiles could be photons. But if not, do not make sense to apply quantum phenomena in the macroscopic world. Ah well, it has a sense: make some fun ;)
Recomended links:
Introduction to Quantum Theory (Quantiki)
Quantum Physics by Benjamin Crowell
What Do You Do With a Wavefunction? by Gary Felder and Kenny Felder
