Can a country create a coastal navy during a war?

Has a country built a modern coastal navy during a war after beginning without one?

Norway in the Second World War is a partial example, mainly through the Free Norwegian forces; Sweden had strong coastal capability but did not start from nothing.

Creating a state-of-the-art coastal navy during an ongoing war is difficult because trained people, suitable small craft, bases, and doctrine must develop together. Norway in the Second World War is a possible example. The qualification matters because much of that growth belonged to the Free Norwegian forces operating with allies rather than a government freely building at home. Sweden is a useful contrast: it maintained a capable coastal navy, but did not begin the war without one.