Lore wise intercontinental travel is monopolized by the kingdom of Arkron. Other nations are banned from developing that specific capability of intercontinental travel. So your nation can have some form of navy and mercentile fleet at the start of the roleplay but is limited to traveling the seas around the continent of Mycoria. There could be branch offices of Arkronian merchant guilds be situated in your republic who are allowed to import/export beyond the continent with maybe some restrictions in volume, and ship construction. I'll have to work that out a bit. This is ofcourse the starting point of the story and not the end. Any form of restrictions placed upon player nations by the Arkronian crown become up for debate as their power starts to decline.