Nanotechnology can seriously aid the world navies who have it.
There will be and are many levels to the development of nanotechnology. This would allow the production of tremendously strong nanotube-steel composites and nanotube composites that can withstand the rigors of sea war and travel far better than current steels. Nano electronics can aid with naval plots and control and more advanced later nanotechnologies like diamondoid assemblers can aid greatly. You could make super submarines and all sorts of amazing new weapons systems galore. Nanotechnology can seriously aid the world navies who have it.