Black Sea strength could not readily reinforce Russia's Baltic fleet. Geography separated the fleet theatres, and even later canal systems served trade and smaller vessels without providing a practical route for ships of the line. Russia therefore had to build a fleet for the Baltic itself. Large sailing warships could contest its open waters while still struggling among the islands and inshore channels. Sweden's archipelago fleet remained formidable despite Russia's growing strength offshore.
Notable Point · 4:24-6:09
Russia's separated fleets and Sweden's archipelago defence
Russia needs a Baltic fleet of its own because large warships cannot readily move between its separated seas, while Swedish inshore forces remain a separate challenge.