I find it mildly amusing that space fleets need to inherit the symbology of aquatic fleets. Something like a mini solar system would have been more appropriate, but it wouldn't surprise me if the same aquatic symbology showed up in the real future.
The alternative of course would be to have the "navy" incorporate "rocket" symbology to represent its true aerospace backbone. The analogy is probably closer to derivation from a submarine fleet which would have more in common with aerospace navigation and helm controls. How many Earth governments have distinct branches of the armed forces exclusively consisting of submarine vessels? I imagine they're all divisions of the naval branch.