There are a lot of ships, but there are also a lot of places on the ocean where there will never be a second ship close enough to forward your packets (areas of south pacific for instance), and they are still painting those areas as having coverage.
I understand you are enamored with the idea of using ground repeaters. It is, however, not what SpaceX is doing. They have been very open from the start that they intend to move the entire transport layer to orbit, and they have launched more than a thousand satellites capable of doing that with laser links. That's what they are using.
Starlink can get full ocean-wide coverage with software today, or hardware after they have lofted enough of it, their choice. Immediate practicality depends on how fast they deploy marine and aircraft terminals. Full coverage of course depends on having lots of such terminals. They could speed that up if they care to.
