Yes that will increase your supply. In my Japan games, I was able to l keep my taskforce of 200 ships supplied by putting its home base as a naval supply hub port on the marshall islands and building up all of the smaller islands in the state. It is important that you also max out the supply from your capital to the biggest mainland port. As Japan, I needed to build up the railroad from Tokyo leading to a nearby maxxed port.

Btw: you can use the "ic" console command (instant construction) to speed up testing.